department of transportation - faa fire safety · the faa, operators, and manufacturer in...

Friday,

May 26, 2000

Part V

Department ofTransportationFederal Aviation Administration

14 CFR Part 39Airworthiness Directives; McDonnellDouglas Model DC–9–80 and MD–90–30Series Airplanes and Model MD–88Airplanes; Final RuleAirworthiness Directives; McDonnellDouglas Model DC–10–10F, DC–10–15,DC–10–30, DC–10–30F, and DC–10–40Series Airplanes, and Model MD–11 and–11F Series Airplanes; Final Rule

VerDate 11<MAY>2000 22:23 May 25, 2000 Jkt 190000 PO 00000 Frm 00001 Fmt 4717 Sfmt 4717 E:\FR\FM\26MYR2.SGM pfrm11 PsN: 26MYR2

34322 Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99–NM–161–AD; Amendment39–11749; AD 2000–11–01]

RIN 2120–AA64

Airworthiness Directives; McDonnellDouglas Model DC–9–80 and MD–90–30 Series Airplanes, and Model MD–88Airplanes

AGENCY: Federal AviationAdministration, DOT.ACTION: Final rule.

SUMMARY: This amendment adopts anew airworthiness directive (AD),applicable to certain McDonnellDouglas Model DC–9–80 and MD–90–30series airplanes, and Model MD–88airplanes, that requires a determinationbe made of whether, and at whatlocations, metallizedpolyethyleneteraphthalate (MPET)insulation blankets are installed, andreplacement of MPET insulationblankets with new insulation blankets.This amendment is prompted by reportsof in-flight and ground fires on certainairplanes manufactured with insulationblankets covered with MPET, whichmay contribute to the spread of a firewhen ignition occurs from smallignition sources such as electrical arcingor sparking. The actions specified bythis AD are intended to ensure thatinsulation blankets constructed ofMPET are removed from the fuselage.Such insulation blankets couldpropagate a small fire that is the resultof an otherwise harmless electrical arcand could lead to a much larger fire.DATES: Effective June 30, 2000.

The incorporation by reference ofcertain publications listed in theregulations is approved by the Directorof the Federal Register as of June 30,2000.

ADDRESSES: The service informationreferenced in this AD may be obtainedfrom Boeing Commercial AircraftGroup, Long Beach Division, 3855Lakewood Boulevard, Long Beach,California 90846, Attention: TechnicalPublications Business Administration,Dept. C1–L51 (2–60). This informationmay be examined at the FederalAviation Administration (FAA),Transport Airplane Directorate, RulesDocket, 1601 Lind Avenue, SW.,Renton, Washington; or at the FAA,Transport Airplane Directorate, LosAngeles Aircraft Certification Office,3960 Paramount Boulevard, Lakewood,California; or at the Office of the Federal

Register, 800 North Capitol Street, NW.,suite 700, Washington, DC.FOR FURTHER INFORMATION CONTACT:Robert Stacho, Aerospace Engineer,Systems and Equipment Branch, ANM–130L, FAA, Transport AirplaneDirectorate, Los Angeles AircraftCertification Office, 3960 ParamountBoulevard, Lakewood, California90712–4137; telephone (562) 627–5334;fax (562) 627–5210.SUPPLEMENTARY INFORMATION: Aproposal to amend part 39 of the FederalAviation Regulations (14 CFR part 39) toinclude an airworthiness directive (AD)that is applicable to certain McDonnellDouglas Model DC–9–80 and MD–90–30series airplanes, and Model MD–88airplanes was published as a notice ofproposed rulemaking (NPRM) in theFederal Register on August 12, 1999 (64FR 43966). A second proposal that wasidentical to the NPRM, except that itaffected additional airplanes, waspublished as a supplemental NPRM onNovember 17, 1999 (64 FR 62613).Those actions proposed to require thata determination be made of whether,and at what locations, metallizedpolyethyleneteraphthalate (MPET)insulation blankets are installed, andreplacement of MPET insulationblankets with new insulation blankets.

Since the issuance of those NPRM’s,the FAA has observed severalprototyping exercises that involved theremoval and replacement of MPETinsulation blankets. The informationobtained from these exercises assistedthe FAA, operators, and manufacturer inunderstanding the technical details andimpact of the requirements of this AD.Certain aspects of these prototypeexercises will be discussed in the FAA’sresponse to the comments received fromthe NPRM’s.

Comments

Interested persons have been affordedan opportunity to participate in themaking of this amendment. Dueconsideration has been given to thecomments received.

The FAA has received comments inresponse to the NPRM’s andsupplemental NPRM’s to Rules DocketNo.’s. 99–NM–161–AD [applicable tocertain McDonnell Douglas Model DC–9–81 (MD–81), DC–9–82 (MD–82), DC–9–83 (MD–83), DC–9–87 (MD–87) seriesairplanes; Model MD–90–30 seriesairplanes; and Model MD–88 airplanes]and 99–NM–162—AD (applicable tocertain McDonnell Douglas Model DC–10–30 and –30F series airplanes, andModel MD–11 and –11F seriesairplanes). Because in most cases theissues raised by the commenters are

generally relevant to both NPRM’s, eachfinal rule includes a discussion of allcomments received.

Support for Proposed AD’s

Several commenters support theintent of the proposed AD’s; however,they request that some changes be made(discussed later).

Unsafe Condition

One commenter states that, becausethe MPET insulation blankets onlypropagate the flame and are not thesource of the flame, the proposed AD’sshould address the unsafe condition(i.e., source of the flame) rather thanpreviously certified material (which metthe flammability standard at one time)that is not creating the unsafe condition.The FAA does not concur. MPETinsulation blankets, when ignited froma small ignition source, such as anelectrical arc, can contribute to thespread of a fire. Such insulationblankets could propagate a small fireand lead to a much larger fire. Potentialignition sources exist in many areas ofthe affected airplanes. It is extremelydifficult to determine where allpotential ignition sources are. Toprovide the level of safety that isexpected by the public for transportcategory airplanes, insulation blanketsconstructed of MPET must be removed.Therefore, the FAA finds that it hasproperly identified the unsafe condition(i.e., insulation blankets constructed ofMPET) addressed by these AD’s.

The same commenter suggests that thesubject blankets be handled as ‘‘attritionreplacements,’’ as intended in theoriginal McDonnell Douglas servicebulletins. The commenter states that,since cabin interior flammability hasbeen addressed already to a large extentby the FAA, MPET insulation blanketscould be treated comparably, and thus,integrated into the overall interiormaterials requirements. (The FAA infersthat the commenter is referring to theprovisions in 14 CFR section 121.312related to ‘‘substantially completereplacement of the cabin interior.’’)These requirements not only mandatestricter new standards, but allow olderairplane interiors to remain in serviceuntil a balanced decision is made tofully reconfigure the cabin. After thatdecision is made, the entireflammability rule must be met on theseolder airplane interiors, as well. Thecommenter argues that insulationblankets could be included, since theproposed requirements are in the samecategory of ‘‘new flammabilitystandards’’ and do not address theactual ignition source.


34323Federal Register / Vol. 65, No. 103 / Friday, May 26, 2000 / Rules and Regulations

The FAA does not concur with thecommenter’s request to handle thesubject blankets as ‘‘attritionreplacements.’’ Attrition is appropriatefor safety enhancements, not to correctidentified unsafe conditions. There is adistinct difference between correctingan identified unsafe condition andenhancing safety. The intent of theinterior material flammabilityenhancement was to provide occupantsmore time to evacuate an airplane beforethe cabin environment would becomeunsurvivable due to smoke and fire. Theexisting interior materials were notdeemed unsafe, and therefore, couldremain in service until the airlinesneeded to replacement them. With thisaction, as discussed above, the FAAfinds that MPET-covered insulationmaterial represents an unsafe conditionthat must be corrected. These AD’s area vehicle for ensuring that all affectedoperators perform the necessary actionsthat will address the identified unsafecondition. Therefore, these AD’s areappropriate and warranted.

One commenter expresses concernthat, because the requirements of theproposed AD’s are extremely costly andcumbersome, resources are being takenaway from more effective measures forimproving aviation safety. Thecommenter states that there are safetygroups (both with wide aviationbusiness basis) that have targeted themost important/critical areas to beaddressed. However, neither of thesegroups has fire on board as its toppriority. The commenter interprets thisto mean that the safety experts lookingat statistical data would ratherconcentrate their efforts in other fields.

While there may be groups thatconcentrate their efforts in other areas,the FAA has identified an unsafecondition that needs to be corrected (asdiscussed above). The activity referredto is primarily aimed at identifyingareas for improved safety, and focusingresources on the most effectivecandidates. This is distinctly differentfrom correcting an identified unsafecondition. Therefore, these AD’s areappropriate and warranted.

One commenter notes that in itsexperience most blankets are wet orsoaking wet in a short time after comingout fairly dry (i.e., after extensivedrying) during a heavy check. Thecommenter asks how it should explainto its mechanics that they have toreplace wet blankets because of a firehazard.

The FAA infers from this commentthat the wet blankets are a result of theatmospheric conditions in which theairplane is being operated or a result ofmoisture accumulation in the belly of

the fuselage. As discussed above, theFAA has identified an unsafe conditionon the affected airplanes that needs tobe corrected. As addressed in thepreambles of the NPRM’s, the FAA hasreceived reports of a number of in-flightand ground fires on in-service airplanesmanufactured with insulation blanketscovered with MPET, which can causefire to spread from a small ignitionsource such as electrical arcing orsparking. The fact that insulationmaterial itself may be wet may notprevent the MPET film material frompropagating the fire to othercombustible materials and causing alarger fire.

One commenter states that thewording ‘‘otherwise harmless electricalarcs’’ in the Summary section in thepreamble of the proposed AD’s ismisleading and requests that thiswording be removed. The commenterreports that there has never been anyMaintenance Steering Group (MSG) 3testing on airplane wiring, and that noone other than the FAA has evenevaluated the problems associated withmomentary metal-to-metal contact ofwires. In addition, the FAA has neverevaluated the effects of spurious signalsemitted from degraded wires that canaffect flight control surfaces, autopilots,rudders, etc.

The FAA does not concur with thecommenter’s request to revise theSummary section of the AD’s. The term‘‘otherwise harmless arcs’’ refers to anelectrical arc that, on insulation filmsother than MPET, would not propagatea fire. In this case, the effect of the arcis negligible. In the case of MPET, anuncontrolled fire could develop. TheFAA points out that these AD’s do notaddress the aging wiring issues that canaffect various systems. As discussed inthe preamble of the NPRM’s, the FAA iscontinuing to investigate various wiringproblems on certain airplanes. Inaddition, the Aging System Task Force(ASTF) is continuing to investigate theneed for specific aging wiringinspections and tests, as well as thepotential effect on systems fromdegraded wiring. The actions requiredby this AD only address the identifiedunsafe condition (i.e., insulationblankets constructed of MPET). TheFAA may consider additionalrulemaking actions to address any otheridentified unsafe condition.

Risk AssessmentSeveral commenters state that, in

concert with the scheduled prototyping,a thorough risk assessment should beaccomplished, particularly on theeffects of replacing insulation blanketson the electrical (including wiring,

cables, and installations), hydraulic, andmechanical systems. One commenterstates that the risk assessment must betaken into account when mandating thescope and compliance of the proposedAD’s. Several commenters state that arisk assessment is needed to determinewhether areas exist where the risksassociated with the replacement ofMPET insulation blankets outweigh thebenefits of replacing them. Risksinherent with disturbing airplane wiringand other permanently installedsystems, particularly on the scalecontemplated by the proposed AD’s, areof primary concern. This and otherrelated risks should be addressed usinga structured method that considers thecharacteristics of MPET and alternativefilms, design and operation of overlyingsystems, susceptibility of those systemsto damage during the replacement ofinsulation under proposed methods,and likely effects of any damage to thosesystems. One commenter states that theproposed AD’s are not supported bysuch an analysis.

The FAA does not concur that aformal risk assessment is necessary. Ifaccomplished properly, the replacementrequired by this AD will not disruptwiring in such a way as to adverselyaffect safety. Generally, the prototypeexercises demonstrated that the requiredreplacement can be accomplishedsafely. In addition, Boeing is revisingthe referenced service bulletins toprovide additional guidance ontechniques to ensure safe replacements.The primary reason for providing anextended compliance time for this AD,as discussed under the next heading, isto ensure that operators have adequatetime to accomplish the replacementsproperly. On the other hand, MPETinsulation blankets have been shown tocreate an unsafe condition that must becorrected. Furthermore, the FAA willrequire any operator/modifier thatdevelops its own installation data toinclude specific instructions to ensurethat any displaced wires, systems, andinstallations are in an airworthycondition after accomplishment of therequired replacement. The FAA willmonitor these areas of concern duringthe accomplishment of the insulationblanket installations. Finally, ifoperators can show that removal andreplacement of MPET insulationblankets in certain areas of an airplanewill create a greater risk of an unsafecondition than leaving the MPETblankets in place, the FAA will considerrequests that provide an acceptable levelof safety under the provision ofparagraph (e) of the final rule. Anyrequest to leave MPET insulation



blankets installed in an airplane mustprovide justification that the identifiedunsafe condition has been minimizedand that an acceptable level of safety ismaintained.

One commenter states that theproposed AD’s should be rewritten tolimit the blanket replacement to areas ofhigh risk, or conversely, retain existingblankets in areas with no wiring or withwiring deemed to pose little or nohazard.

The FAA does not concur. Notechnical justification, criteria, or datawere submitted to support thecommenter’s request. Potential ignitionsources exist throughout the airplaneand insulation blankets constructed ofMPET film material are locatedthroughout the airplane. It is, therefore,extremely difficult to identify high riskareas and areas of little or no risk. TheFAA finds that MPET insulationblankets in all areas of the affectedairplanes must be addressed.

One commenter states that therequirements of the proposed AD’sshould be recast into phases so as tofirst respond across the worldwide fleetof affected airplanes to the areas ofhighest perceived risk. Thereafter, theareas of lesser perceived risk can bedealt with at a more appropriate pace.Targeting the highest perceived riskareas of the worldwide fleet of affectedairplanes first would provide thegreatest decrease in risk across the fleetmost quickly. This approach also wouldmake the best use of limited resources,lessen the substantial adverse impact tothe traveling public of excessive fleetgroundings, and somewhat reduce thesubstantial economic burden to theairlines.

The FAA does not concur with thecommenter’s statement that therequirements of the final rule should berecast into phases. As discussed aboveunder the heading ‘‘Unsafe Condition,’’potential ignition sources exist in manyareas of the affected airplanes. It isdifficult to identify high risk areas andareas of little or no risk. Therefore, theFAA finds that MPET insulationblankets in all areas of the affectedairplanes must be replaced. With thechange in the compliance time from 4to 5 years in this AD, excessive fleetgrounding should not take place.Adequate maintenance facilities areavailable to complete this action withinthe required time period.

Compliance Time for ProposedReplacement of MPET InsulationBlankets

Several commenters request that thecompliance time for accomplishing theproposed replacement of the MPET

insulation blankets be extended fromthe proposed 4 years to a range of 5years to 8 years. The commenters statethat such an extension will allow thereplacement to be accomplished duringa regularly scheduled ‘‘D’’ check orheavy maintenance visit, therebyeliminating any additional expensesthat would be associated with specialscheduling. The commenters express aconcern about the availability offacilities and trained personnel, eitherdomestically or offshore, to accomplishtasks of this magnitude.

One commenter states thatmaintenance planning can only be doneeffectively once all details of the workto be accomplished and all downtimesneeded to perform the work are knownin detail. Therefore, the compliancetime should only start once all thesedetails have been clarified.

One commenter states that theproposed AD’s do not provide sufficienttime for accomplishment of theprototyping effort. Wholesale removal orrelocation of wiring not designed forremoval in areas where access isdifficult can lead to incidental damageeven with the best maintenancepractices. Given the problems of access,multiple blanket sections will now berequired in many fuselage areas toreplace a single original blanket. Thiswill lead to new designs, templates, andpart numbers. The commenterconcludes that this cannot happen in anorderly fashion without completing aprototyping effort on at least oneairplane.

The FAA concurs that an extension tothe compliance time is warranted. TheFAA’s intent was that the replacementbe conducted during a regularlyscheduled maintenance visit for themajority of the affected fleet, when theairplanes would be located at a basewhere special equipment and trainedpersonnel would be readily available, ifnecessary. Based on the informationsupplied by the commenters, the FAAnow recognizes that 5 years correspondsmore closely to an intervalrepresentative of most of the affectedoperators’ normal maintenanceschedules. The FAA finds that a 4-yearcompliance time would have asignificant impact on scheduling andcost and might result in hurriedaccomplishment of the requiredreplacement, which could result inpotential damage to associated wiring.This decision is supported byexperience from the prototypeinstallations, which demonstrated thatthe required replacement procedures arecomplex in some areas, and thatadequate time and facilities arenecessary to ensure that they are

completed safely and correctly.Paragraphs (a) and (c) of the final rulehave been revised to reflect acompliance time of 5 years. The FAAdoes not consider that this extensionwill adversely affect safety.

One commenter supports theproposed 4-year compliance time foraccomplishing the proposedreplacement of the MPET insulationblankets. The commenter states that,while some operators feel it is not apractical time period, the proposedcompliance time is reasonable andpractical to retrofit all of the affectedairplanes, utilizing airline and thirdparty maintenance facilities. Thecommenter also states that it and othermaterials manufacturers are fullyprepared and have the capacity tosupport this effort. Another commenterstates that the proposed 4-yearcompliance time is a very generousallotment of time and would not wantto see the proposed AD’s delayed anyfurther.

The commenters did not provide anydata to support their position. For thereasons described previously, the FAAfinds that a 5-year compliance time isreasonable and practical to retrofit all ofthe affected airplanes rather than the 4-year compliance time proposed by theoriginal NPRM and supplementalNPRM.

Two commenters request that thecompliance time for accomplishing theproposed replacement be shortened.One commenter states that the proposedcompliance time of 4 years is toolengthy given the fire hazard introducedby MPET insulation blankets. Thesecond commenter states that quickeraction is necessary if the conditions ofthe wiring on affected airplanes areanything like what was discovered inthe 737’s emergency grounding issue ofMay 98, wires found damaged on theSpace Shuttle Columbia, or numerousinstances of wire insulation failurecoming out of the Aging TransportSystems Rulemaking AdvisoryCommittee (ATSRAC)/ASTFinspections (15 service bulletinsupgraded to alert status on Model MD–11 series airplanes alone) or alert servicebulletins on the 727’s.

The FAA does not concur with thecommenter’s request to shorten thecompliance time. As discussedpreviously, the FAA considered thesafety implications, parts availability,and normal maintenance schedules fortimely accomplishment of replacementof the MPET insulation blankets. Inconsideration of all of these factors, theFAA determined that the compliancetime, as revised, represents anappropriate interval in which



replacement of the MPET insulationblankets can be accomplished in atimely manner within the fleet and stillmaintain an adequate level of safety.The FAA encourages operators toaccomplish this modification as soon aspossible. The commenter points outseveral incidents associated withairplane wiring. The FAA is addressingthese issues as they are identified. Thecommenter is correct that these wiringincidents are the focus of ATSRAC andASTF activity. However, these wiringissues are not the subject of this AD.

One commenter requests that the FAAconsider a 4-year compliance time toaccomplish the proposed replacementonly in areas that are readily accessible(i.e., areas where extraordinary meansare not required to gain access). TheMPET insulation blankets for certaindefined areas of the cockpit andelectronics bay(s) should not bereplaced or should be replaced whenthose areas are made accessible. Thecommenter states that replacement of 98percent of the insulation on the affectedairplanes will provide an equivalentlevel of safety to those airplanes notaffected by the proposed AD’s.Considerable time will have to be addedto the proposed compliance time toaccommodate a complete replacementwithout forcing some airplanes to begrounded due to lack of maintenancecapacity.

The FAA does not concur with thecommenter’s request to require acompliance time of 4 years only forreplacement areas that are readilyaccessible. Although the prototypeinstallations have shown thataccomplishment of the requiredreplacement in the cockpit andelectronic compartment is physicallychallenging, potential ignition sourcesand the identified unsafe condition existin areas that are not readily accessible.Therefore, the FAA finds that MPETinsulation blankets in all areas of theaffected airplanes must be replaced.However, as discussed previously, theFAA has extended the compliance timefor the required replacement from 4years to 5 years. While not intended toaddress the issue of inaccessible areas,the extension of the compliance time byone year should help alleviate theconcern for grounding of airplanes dueto lack of maintenance capacity.

Two commenters request that theFAA ensure that sufficient insulationmaterial of appropriate quality isavailable. Supply shortages could createconditions in which the work needs tobe performed under time pressure. Onecommenter notes that there is only oneblanket covering material that iscurrently approved, and only one

qualified test apparatus available foroperators to perform American Societyfor Testing and Materials (ASTM) E648tests on other products. The commenteralso notes that the airplanemanufacturer has stated that it has onlyone qualified supplier for manufacturedblankets. The commenter is uncertain ifthe blanket manufacturer can meetreplacement demands within theproposed 4-year compliance time.Furthermore, the commenter states thatthere are no dimensioned drawingsavailable to 14 CFR part 121 operatorswho might plan to fabricate their ownblankets. Templates must be plotted andobtained from the airplanemanufacturer, which is a timeconsuming process.

Various insulation blanket materialsuppliers state that there is no cause forconcern over the availability of thematerials specified in the proposedAD’s. Metallized TedlarTM (i.e.,polyvinylfluoride), polyimide film,TedlarTM and polyimide tapes, andfiberglass are abundant and are readilyaccessible to support all retrofitrequirements.

The FAA has assessed the availabilityof materials required by this AD and hasdetermined that required materials andmanufacturing sources should beavailable for modification of the U.S.fleet within the 5-year compliance time.The FAA encourages operators toreview their airplanes to assess theirindividual needs for materials and planaccordingly. The FAA anticipates thatoperators will accomplish therequirements of this AD at the earliestpracticable maintenance opportunity tolessen the burden toward the end of thecompliance time. In addition, theairplane manufacturer is preparinginstallation kits that can be utilized toaccomplish the required replacement.Also, operators and modifiers havedeveloped and are continuing todevelop their own data (templates anddrawings) to accomplish this requiredreplacement. While this may be a timeconsuming process for some, it can beaccomplished.

Inadequate Procedures and Informationin Referenced Service Bulletins

Several commenters state that thereplacement procedures andinformation specified in the referencedservice bulletins (i.e., McDonnellDouglas Service Bulletins MD–90–25–015, Revision 01, dated November 5,1997; MD80–25–355, Revision 01, datedNovember 5, 1997; DC10–25–368, datedOctober 31, 1997; and MD11–25–200,Revision 01, dated March 20, 1998) areinadequate for reasons discussed below.

Several commenters state that theAccomplishment Instructions of thereferenced service bulletins address thefabrication of insulation blankets butprovide no instructions for installation.Detailed instructions for installation areessential to avoid risks duringinstallation, particularly in crucial areaswhere wiring or other systems aredensely concentrated. Damage toinstalled systems can result in latentfailures of critical flight systems andgeneration of electrical ignition sources.The unprecedented scope of the workinvolved in moving and replacing wiresand systems, and the fact that nothingsimilar has ever been attempted,introduce a new and unquantifiedamount of risk.

One commenter states that Boeing hasacknowledged that instructions toremove and reinstall some equipmentracks and related structures, which arenecessary to accomplish the proposedreplacement, do not exist in currentmaintenance documents and will needto be developed. Specific aspects of theproposed replacement are beyond thescope of any currently authorizedmaintenance procedures. The membersof the Boeing Recovery andModification (RAM) Team are the onlypersonnel trained and authorized todisassemble and reassemble certaincritical areas. Several commenters statethat Boeing is planning to issue revisedservice bulletins around June 2000. Onecommenter states that Boeing shouldissue detailed service bulletins to coverthe scope of the NPRM’s and all relatedtest criteria and requirements associatedwith insulation blanket replacement andremoval/installation of associatedequipment/components. Onecommenter states that the servicebulletins should be revised to includethe above information.

The FAA acknowledges that theinstructions appear to be generic,without reference to specific locationsin the airplane. However, it is stillpossible to complete the replacementrequired by this AD by developing thenecessary installation data inconjunction with existing maintenanceprocedures. Since the issuance of theNPRM’s, the manufacturer, inconjunction with operators, hascompleted prototype installations.Based on the results of the prototype,the manufacturer is developingrevisions to the referenced servicebulletins that will contain additionalinstallation information andinstructions. These revised servicebulletins are scheduled for completionin June 2000. Any new or revisedservice bulletins will containprocedures to maintain/test the integrity



of the wiring after accomplishment ofthe replacement of any MPET insulationblanket. The FAA is planning to reviewand approve the revised servicebulletins under the AMOC provision ofparagraph (e) of the final rule.

In addition, the FAA is aware thatcertain operators and modifiers aredeveloping their own installation data.The FAA may approve requests for anAMOC under the provisions ofparagraph (e) of this AD if sufficientdata are submitted to substantiate thatsuch a design change would provide anacceptable level of safety.

The FAA does not concur with thecommenter that the members of theBoeing RAM team are the onlypersonnel that can address certain areasof the airplane. The FAA finds thatmany operators have the expertise toaccomplish the required replacement. Inaddition, Boeing intends to include thenecessary instructions in the revisedservice bulletins.

Several commenters state that thereferenced service bulletins not onlyrefer to materials tested in accordancewith Standard Test Method ASTM E648and approved by the FAA as a methodof compliance with the requirements ofthe proposed AD, but also refer tomaterials that do not meet the newrequirements. Moreover, other materialsacceptable for compliance with therequirements of the proposed AD arenot listed in the referenced servicebulletins.

The FAA concurs that the referencedservice bulletins refer to materials thatdo not meet the requirements of thisAD. When the referenced servicebulletins specified in the NPRM’s wereissued in 1997, the insulation blanketfilm material listed in those servicebulletins were considered acceptable forinstallation. Since the issuance of thoseservice bulletins, however, only one ofthe two metallized TedlarTM coversspecified in the referenced servicebulletins has been demonstrated to beacceptable for compliance with thereplacement requirements of paragraph(c) of this AD (as indicated in NOTE 4of the AD) based on flammability testingusing the criteria specified in the finalrule. The revised service bulletins willonly list material that has beenapproved by the FAA. Under theprovisions of paragraph (c) of this AD,the FAA may approve other filmmaterial that is shown to meet theflammability test method specified inthe final rule. Also, under theprovisions of paragraph (e) of this AD,the FAA may approve requests forapproval of an AMOC for insulationblankets other than those specified inthe service bulletins referenced in the

final rule that are shown to meet theflammability test method specified inthe final rule and all other airworthinessregulations.

Several commenters state that, due toage, identification stamps on the MPETinsulation blankets may be unreadable.The referenced service bulletins aremissing instructions for determiningwhether such blankets are constructedof MPET.

Although the referenced servicebulletins are missing instructions fordetermining whether insulationblankets are constructed of MPET, theFAA finds that such a determinationcan be made without such instructions.MPET insulation blankets are extremelyshiny when compared to all otherinsulation blanket cover material, andcan be readily recognized by trainedmaintenance personnel. It is alsopossible to use known MPET material asa comparison sample to assist in theidentification should the markings notbe readable. Paragraph (a) of the finalrule has been revised to clarify themethod of identifying MPET. MPETinsulation blankets can be identified bythe following markings: (1) DMS 2072,Type 2, Class 1, Grade A; (2) DMS 2072,Type 2, Class 1, or (3) DMS 1996, Type1. The FAA has revised NOTE 2 of thefinal rule to clarify these markings.

Several commenters state that thereferenced service bulletins specify theleast effective method for the fabricationof new insulation blankets. Fewoperators are equipped or have thecapability or capacity to manufacturetheir own blankets. Four sources ofinsulation blankets were evaluated intechnical meetings with themanufacturer. Of these four sources,operators viewed blankets provided inkits by the manufacturer as the mostefficient and practical. Such kits wouldfacilitate the earliest completion date ofa replacement program, would preservethe thermoacoustic characteristics ofinsulation systems and certificatedconfiguration of affected airplanes, andcan be supported according to themanufacturer. In addition, nodimensional blanket drawings andtemplates for making the blankets areavailable.

Although the method for fabricationof new insulation blankets specified inthe referenced service bulletins may notbe the most efficient method for thecommenters, the FAA finds that it ispossible to develop the necessary datato manufacture blankets in accordancewith the instructions of the referencedservice bulletins. The FAA is aware thatBoeing is developing replacement kits.The information necessary to purchasethese kits will be included in the

revised service bulletins (as discussedpreviously). However, the revisedservice bulletins are not scheduled to becompleted until June 2000. The FAAhas decided not to delay this action inanticipation of the service bulletins,since the release date is not absoluteand this action is necessary to addressan identified unsafe condition.Therefore, the FAA may approverequests for an AMOC under theprovisions of paragraph (e) of this ADonce the revised bulletins are issued.

In addition, the FAA acknowledgesthat templates may not be available foroperators to make new insulationblankets. However, the referencedservice bulletins do describe proceduresfor removing the subject insulationblankets and using those blankets astemplates for making new insulationblankets. While some operators may notbe equipped or may decide not tomanufacture the replacement blankets,there are adequate resources available inthe industry to accomplish themanufacturing.

Several commenters state that thereferenced service bulletins provide nolabor estimates. One commenter statesthat it is not aware of any large transportcategory airplane that has been removedfrom service, has had its insulationreplaced, and has been returned toservice. This lack of experience andlabor estimates from the manufacturerwould impair the planning required ofoperators and their ability to provideaccurate comments to the proposedAD’s.

The FAA does not concur. The FAAacknowledges that the referencedservice bulletins do not provide laborestimates. However, as indicated underthe heading ‘‘Regulatory EvaluationSummary’’ in the preamble of theNPRM’s and supplemental NPRM’s, aPreliminary Cost Analysis and InitialRegulatory Flexibility Analysis todetermine the regulatory impacts of theproposed AD’s were included in theRules Docket No.’s 99–NM–161–AD and99–NM–162–AD. A summary of thoseanalyses was contained under that sameheading in the preamble of the NPRM’sand supplemental NPRM’s. In addition,the manufacturer, operators, andmodifiers have developed estimatesbased on the prototype installationscompleted to date. (The FAA discussesthe comments to the cost estimate of theproposed AD’s in more detail, below,under the heading ‘‘RegulatoryEvaluation Summary.’’)

In response to the original NPRM’s,several commenters state that themanufacturer has indicated that theairplane effectivity in the referencedservice bulletins is currently being re-



evaluated and may be revisedsubstantially. This lack of accurateairplane effectivity also would impairthe planning required of operators andtheir ability to provide accuratecomments.

The FAA concurs that the effectivitylisted in the service bulletins is notcorrect. As indicated under the heading‘‘Differences Between the Proposed ADand Service Bulletins’’ in the preambleof the NPRM’s, the FAA realizes that theeffectivity listing of the referencedservice bulletins not only includesairplanes manufactured with MPETinsulation blankets, but airplanesequipped with other materials that aremuch more difficult to ignite thanMPET. The FAA has determined thatonly airplanes manufactured withMPET insulation blankets are subject tothe identified unsafe condition.Therefore, paragraph (a) of the AD’srequires that a determination be made ofwhether, and at what locations, MPETinsulation blankets are installed. Inaddition, the applicability specified inthe final rules, based on thesupplemental NPRM’s, includes fewerairplanes than specified in the servicebulletins. In addition, the applicabilitystatement of the final rule, Rules DocketNo. 99-NM–162-AD, has been revised toclarify the airplanes that are subject tothe identified unsafe condition, whichis discussed below, under the heading‘‘Revise Applicability of Proposed AD.’’

Several commenters state that someaccessibility issues have not beenaddressed. One commenter requests thatthe removal/replacement requirementsbe re-evaluated to exclude replacementinsulation blankets in those‘‘inaccessible places’’ of the airplanes.Three to four percent of the MPETinsulation blankets are buried beneathstructure and wiring in areas like theelectrical and equipment (EE) bay andthe flight deck and will require as muchas 70 percent of the total man hours toreplace.

The FAA does not concur thatreplacement of MPET insulationblankets should not be required in‘‘inaccessible’’ areas. The areasidentified by the commenters (i.e., theEE bay and flight deck) are areas wherepotential ignition sources (i.e., electricalarcing) are likely to exist and are,therefore, susceptible to the identifiedunsafe condition. During the prototypeexercises and subsequent inspections ofthe EE bay and flight deck, the FAAlearned that most Model DC–9–80 andMD–90–30 series airplanes do not haveMPET insulation blankets in these areas.It is, however, the operator’sresponsibility, as required by paragraph(a) of this AD, to determine whether,

and at what locations, MPET insulationblankets are installed in each airplane.Therefore, contrary to the commenters’assertion, the total labor costs associatedwith replacement of the MPETinsulation blankets in the EE bay andflight deck will not be the mostsignificant portion of the total cost ofthe AD.

One commenter requests that the FAArevise the proposed AD to incorporatespecific references to industry guidancematerial on wire inspection anddisturbance. As a minimum, suchreferences should include AdvisoryCircular 25–16, ‘‘Electrical Fault andFire Protection and Prevention.’’

The FAA does not concur. Operatorsand modifiers should be aware of theexisting guidance and the revisedservice bulletin instructions (discussedabove), which, based on the prototypingthat has been accomplished, will specifywiring inspection information that maybe needed.

One commenter requests that the FAAdevelop and require post-modificationwiring inspections to verify the integrityof the wiring insulation. The FAAconcurs that any damage done to wiringor other components in the course of therequired replacement needs to becorrected. In fact, if maintenancepersonnel are aware of damage, whetheror not caused by replacement of theMPET insulation blankets, they areobligated to document it and initiateappropriate corrective action. Operatorsare required by 14 CFR parts 91, 121,and 135 to maintain their airplanes inan airworthy condition after anyalteration or repairs are made to theairplane. Also, based on the prototypingthat has been accomplished, the revisedservice bulletins will provide anyspecific wire integrity inspection thatmay be needed. Therefore, no change tothe final rule is necessary.

Coordination With Wiring AD’sSeveral commenters state that they

understand that other NPRM’s are in thedevelopment phases, which wouldrequire inspection of airplane wiring,and would deal with the same issuesthat have brought about the subjectproposed AD’s. Some of thesecommenters state that these NPRM’sshould not be developed, mandated,and undertaken separately, but rathershould be part of a carefully thought outand coordinated process and program. Aproperly developed plan must considerthat each time such disruption ofairplane wires/systems takes place,there is an increasing opportunity forcollateral damage to those wire/systemswith unknown future safetyimplications. Such a plan also should

recognize that the insulation proposedto be changed is not really the source ofany fire problem and that properrectification of the issues beingconsidered might better lie in a carefullythought out and researched wiring AD.One commenter states that it would beefficient to combine the requirements ofthe proposed AD’s with the wiringrequirements that will be proposedsoon. One commenter states that Boeingis developing several service bulletinsdedicated to the inspection andmaintenance of airplane wiring.However, these service bulletins willnot be available in time to coincide withthe insulation blanket replacementshould the current NPRM’s, with theirproposed timing, become law.

The FAA does not concur that AD’saddressing specific unsafe wiringconditions should necessarily providefor compliance times that are concurrentwith this AD. In some cases, thecorrective actions for those unsafeconditions are simple maintenanceactions that can be accomplishedquickly. It would be inappropriate toallow those unsafe conditions tocontinue during the extendedcompliance time allowed by this AD.The FAA does concur that any AD’saddressing general wiring inspectionsfor unsafe conditions would be bestaccomplished in conjunction with thereplacement of MPET insulationblankets in affected areas. Suchcoordinated actions would certainly bemost efficient for operators. The FAAdoes not concur with the commenters’request to combine the requirements ofthis AD with any proposed actions toaddress general wiring issues. Suchaction may delay correction of theunsafe condition of this AD byextending the compliance time further.The FAA will take into considerationthe compliance time of this AD in anyfuture action for general wiringinspection to minimize the duplicationof aircraft downtime associated withaccomplishing the actions of this AD.

Revise Applicability of Proposed ADOne commenter notes that paragraph

(a) of the proposed AD states ‘‘* * *determine whether, and at whatlocations, insulation blanketsconstructed of MPET are installed. Thisdetermination shall be made in amanner approved by the FAA.’’ Thecommenter states that this wording isvery unclear to operators and that theFAA should coordinate with Boeing todetermine more precisely what theapplicable airplanes are.

Based on the commenter’s statementthat ‘‘the FAA should coordinate withBoeing to determine more precisely



what the applicable airplanes are,’’ theFAA finds that clarification isnecessary. After inspecting in-serviceairplanes, the FAA has determined thatall affected airplanes may not haveMPET insulation blankets throughoutthe fuselage. Some airplanes may havevery little MPET insulation blanketsinstalled and others may have 100percent installed. The FAA also hasdetermined that, based on themanufacturer’s records alone, it is notpossible to determine precisely theconfiguration of each individualairplane. Therefore, paragraph (a) of thefinal rule requires that operatorsdetermine whether, and at whatlocations, insulation blanketsconstructed of MPET are installed. IfMPET insulation blankets are notinstalled, no further action is requiredby this AD.

The manufacturer states that it iscontinuing to verify the actual extent ofMPET-covered insulation on airplanesdelivered from the factory. In responseto the original NPRM’s, themanufacturer states that additionalModel DC–9–87 (MD–87), DC–10, andMD–11 series airplanes, and KC–10A(military) airplanes need to be includedin the applicability of the NPRM’s, andat least some Model DC–9 seriesairplanes should be excluded. Whenthat effort is complete, the manufacturerstates that it will issue new servicebulletin information. One commenterstates that the applicability statement ofNPRM, Rules Docket No. 99–NM–162–AD, is incorrect. The commenter statesthat the manufacturer has indicated thatMPET insulation blankets were used onModel DC–10 series airplanes, fuselagenumbers 359 through 381 inclusive, and432 through 436 inclusive, and ModelMD–11 series airplanes, fuselagenumbers 447 through 602 inclusive. Inaddition, MPET insulation blanketswere used on ducting installed in ModelMD–11 series airplanes, fuselagenumbers 603 through 632 inclusive.

The FAA acknowledges that theapplicability statement of the originalNPRM’s was incorrect. Following theissuance of the NPRM’s, the FAAidentified additional airplanes that weresubject to the identified unsafecondition and issued supplementalNPRM’s to reopen the comment periodto provide additional opportunity forpublic comment. The applicabilitystatement of the supplemental NPRM’sincluded the fuselage numbers of theairplanes the commenter referred toabove.

One commenter states that theapplicability statement of supplementalNPRM, Rules Docket No. 99–NM–162–AD, is incomplete. The commenter

notes that it operates four Model DC–10–15 series airplanes, three of whichfall within fuselage numbers 359through 632 inclusive (i.e., fuselagenumbers 362, 365, and 374), which weremanufactured between June 1981 andJanuary 1982. The commenter requeststhat the applicability statement of thesupplemental NPRM be revised toinclude Model DC–10–15 seriesairplanes. The FAA concurs. Theapplicability statement of the subjectsupplemental NPRM correctlyreferences the specific manufacturer’sfuselage numbers of all affectedairplanes, including those fuselagenumbers for Model DC–10–15 seriesairplanes. Therefore, the FAA finds thatit is necessary to revise the applicabilitystatement of the subject final rule toinclude all affected series of Model DC–10 airplanes, specifically Model DC–10–10F, DC–10–15, and DC–10–40 seriesairplanes.

One commenter requests that theapplicability of NPRM, Rules DocketNo. 99–NM–161–AD, be revised to‘‘[m]anufacturer’s fuselage number 1011through 2241 inclusive; certified incommon carriage operations.’’ Thecommenter states that private operatorswere not considered when studying theeffects of the proposed AD’s. Privateoperators who operate under 14 CFR91.501 need to be separately consideredwhen they are faced with rules that aredirected at air carriers. Transportcategory ‘‘Private Carriage’’ operators,who operate under 14 CFR 91.501, arepart of the general aviation populationand do not offer service to the public ora segment of the public. Generalaviation operators’ airplanes are notheld (and are not expected to be held)accountable to the same regulationstandards as ‘‘Common Carriage’’operators. The commenter also statesthat significant differences in airplaneutilization, interior, and operation makethe likelihood of in-flight fire threat dueto MPET insulation blankets on ‘‘PrivateCarriage’’ airplanes extremely remote.Therefore, the exclusion of ‘‘PrivateCarriage’’ airplanes from theapplicability of this NPRM would notjeopardize public interest.

The FAA does not concur with thecommenter’s request to revise theapplicability of the subject rule asstated. The identified unsafe conditionand potential consequences addressedby this AD are not any different forairplanes utilized in private operationversus ones operated in commoncarriage.

One commenter states that theproposed AD’s do not address affectedairplanes outside the noted applicabilitythat may have been retrofitted with

MPET insulation blankets duringservice. This implies that the FAA’sinvestigation has determined that smallamounts of MPET on those airplanes donot pose an unsafe condition.

Regarding post-delivery installation ofMPET, the FAA does consider that suchinsulation is unsafe. Most operators donot retain records identifying on whatairplanes such insulation has beeninstalled. Therefore, to address thisunsafe condition, an AD would have torequire that all operators inspect allairplanes of any type to identify therelatively small amount of suchinsulation that may have been installedduring post-production maintenance.The FAA does not consider that such arequirement would be practical or costeffective. However, as with any otherunsafe condition, when an operatorbecomes aware that MPET insulationblankets have been installed, thematerial should be removed to maintainthe airplane in an airworthy condition.

Flammability Test Method NotAdequately Developed/Defined

Several commenters state that theproposed test method seemsinsufficiently developed to beconsidered the new standardflammability test. The commentersaddressed several issues, including:

• The validity of the test method;• Qualification of the test method;• Details of the test procedures; and• Materials and approval process.

Validity of Test Method

One commenter notes that it has builta test unit and conducted tests on it.The commenter has verified the resultsof the FAA Technical Center tests, butbelieves there are serious limitations onthis test’s utility for predicting howinsulation coverings will burn when inplace on an airplane. In addition, thecommenter states that the mechanismby which films can pass the RadiantPanel Test is for the material to shrinkaway from the heat source. Othermaterials, such as polyimide film, passthe Radiant Panel Test by not ignitingand shrinking away from the heatsource. Two other commenters state thatthe best of TedlarTM and MylarTM (i.e.,3 polyethyleneteraphthalate) filmsshrink away in the presence of flameand are no help at all in containing fire.The TedlarTM material that passes thetest shrinks away from the heat sourcebefore the ignition source can beapplied to the surface of the testmaterial. Thus, there is no material toignite. The commenter states that theRadiant Panel Test may not replicate thecondition on an airplane where blankets



are restrained and multiple layers areoften part of the blanket construction.

The commenter further states that it ispossible for polyethyleneteraphthalate(PET), MPET, or other plastics that aremore combustible than TedlarTM to passASTM E648, if treated to have desirableheat shrink characteristics. The onlyother requirement for insulationcoverings is the 12-sec vertical burn,which is recognized as inadequatebecause MPET materials can pass it. Thecommenter notes that the proposedstandard may leave the door open in thefuture for combustible materials to beinstalled on airplanes.

The FAA does not concur with thecommenter’s statement that films canpass the Radiant Panel Test by shrinkingaway from the heat source and are nohelp in containing a fire. The purposeof the test is to establish the flamespread characteristics of insulationblanket materials under realisticconditions. The results of this test havebeen correlated with full-scale testing,conducted by the FAA TechnicalCenter, in which insulation wasinstalled in fuselage sections in arepresentative fashion. Certain materialsthat shrink when exposed to heat havebeen shown to prevent propagation of afire. In addition, for these same reasons,the FAA does not concur with thecommenter that the FAA TechnicalCenter tests have serious limitations.The FAA finds that the insulationmaterial tested in accordance with themethod specified in the AD will havemuch better flame spread characteristicsthan MPET, which was shown tocomply with the current Bunsen BurnerTest specified in the regulations, andsubsequently, determined to haveunsafe flame spread characteristicswhen ignited from a small ignitionsource.

One commenter states that the bestsituation is to have insulation coveringfilm that does not burn in the RadiantPanel Test. The commenter contendsthat the test should screen out materialthat does not perform as well aspolyimide film.

The FAA does not concur that the testmethod must screen out materials thatdo not perform as well as polyimidefilms. As discussed previously,materials, including polyimide films,that pass the Radiant Panel Test performmuch better in full-scale testing thanMPET insulation blankets that are thesubject of this AD.

Qualification of the Test MethodOne commenter expresses concern

that the FAA has not yet publishedupdated flammability standards thatwill allow for the development and

testing of materials other than thosecited in previous McDonnell Douglasservice bulletins, which specify thereplacement of MPET with two types ofmetallized TedlarTM. The commenternotes that the FAA has approved onlyone type of specified metallizedTedlarTM after it successfully passed anASTM flame spread test. Thecommenter emphasizes that it is urgentthat the FAA provide its own applicabletest standard to facilitate the rapidreplacement of MPET with othermaterials that will have superior fireresistant characteristics.

One commenter requests that the FAArevise the proposed AD’s to ‘‘moreclearly require the FAA Radiant PanelTest, which was derived from ASTME648,’’ and to define the test beforeapproving specific films. Thecommenter states that ASTM E648 ismuch different than the Radiant PanelTest developed by the FAA TechnicalCenter. The Radiant Panel Test uses thesame enclosure, a radiant panel, and thesame basic concept as the ASTM E648test. However, the Radiant Panel Testhas had several modifications includinga different heat flux, different ignitionsource, and a modified sample holder.The commenter notes that results of theRadiant Panel Test vary widely whentest specifications are changed.Therefore, the specification of any filmas passing the test prior to thecompletion of the test method is notwarranted. It is possible for films thatcurrently fail the existing test to passwhen the test procedures or chamber isfully defined. Conversely, films thatcurrently pass the test can fail.

One commenter states that industryexperts should discuss the successcriteria of ASTM E648 further. Thiscommenter notes that these changes tothe standard and success criteria havenot been subject to round robin testingand outside peer review, so variousaspects of their merit are questionable.One commenter suggests that roundrobin testing with clearly identifiable/achievable pass/fail criteria beperformed by the industry to validatethe repeatability of the test proceduresprior to release of the proposed AD’s.Validated criteria would produce anequivalent level of safety to materialcurrently in production and in use inthe fleet, which is deemed acceptable.

The FAA concurs with thecommenters concerning the reference toASTM E648 in the NPRM’s and findsthat clarification is necessary. The FAAhas been developing for some time newflammability standards for insulationmaterial. Research has been conductedon the various types of insulationmaterial to determine their effectiveness

on both flame spread and fuselageburnthrough. As a result, the FAA hasdeveloped a new flame spread testmethod. The flame spread test methodspecified in this AD is a modifiedversion of the ASTM E648 flammabilitystandard and test apparatus.Modifications to ASTM E648 testapparatus have been made to moreclosely reflect the fire conditions in anairplane environment. The FAA hasprepared a document to reflect the flamespread test method to be used for testingof replacement insulation blankets forthis AD. It is identified as ‘‘Test Methodto Determine the Flame SpreadCharacteristics of Thermal/AcousticInsulation Material for Replacement ofMPET.’’ For the purposes of correctingthe identified unsafe condition of thisAD, the FAA finds that this flamespread test method is sufficientlydeveloped.

The FAA also has developed aprocedure for utilizing the FAATechnical Center flame spread testapparatus to qualify materials for thisAD. The procedure for utilizing the testapparatus of the FAA Technical Centeris identified as ‘‘Ground Rules for Useof Technical Center Facility forTesting.’’

The flame spread test method andprocedure for using the FAA TechnicalCenter test apparatus are both includedin Appendix 1 of this AD.

As paragraph (c) of the NPRM’s iscurrently worded, some commentersmay misinterpret that the replacementinsulation blankets must be constructedof materials tested in accordance withthe original ASTM E648 flammabilitystandard, rather than tested inaccordance with a new flame spread testusing an apparatus derived from ASTME648 in accordance with a methodapproved by the FAA. Paragraph (c) ofthe final rules has been revised to clarifythe flame spread test method forreplacement insulation blankets. TheLos Angeles Aircraft Certification Office(ACO) will work closely with other FAAACO’s and the FAA Technical Center toassist operators/modifiers in qualifyingnew materials for compliance with therequirements of this AD.

The FAA concurs that the methodspecified is not yet a ‘‘standard.’’However, the method is sufficientlydeveloped for this AD and, beforeadoption as a standard, will undergo thekind of industry qualification proposedby one commenter. The FAA partiallyconcurs with the commenter’s statementthat round robin testing is necessary andthat the success criteria of the flamespread test method should be discussedfurther. Prior to incorporation of a newflame spread test method into the



Airworthiness Standards for transportcategory airplanes (14 CFR part 25), thetest method will be subject to roundrobin testing. In fact, this process iscurrently underway within theInternational Aircraft Materials Fire TestWorking Group.

With respect to changes in the flamespread test method that may causecertain materials to go from acceptableto unacceptable, or vice versa, the FAAdoes not agree that this is an issue.Refinements to the test method will bemade to improve the repeatability of thetest, not to change the test results.Materials that are marginal will performmarginally regardless of the details ofthe method.

One commenter states that itunderstands that the FAA has plans toreplace the standard gas-fired radiantpanel with an electric panel, and thatthe flame ignition source is a singlecone non-standard burner as opposed tothe T-type burner method specified inASTM E648. The commenter contendsthat differences between the FAAmethod and ASTM E648 are confusingto both testing labs wishing to provideservices to FAA-regulated clients aswell as suppliers of insulation who areunclear as to what the specification willbe for the products they produce for theaerospace industry. The commenterstates that ‘‘specification of a non-standard test apparatus and conditionsby the FAA end up creating a wholeother set of devices which must befabricated and maintained separatelyfrom their standard ‘parent devices’removing the economic benefits whichuse of consensus developed publicsector standards provide.’’

The FAA does not concur for thereasons noted previously. In addition,since the apparatus specified is not usedfor any other aviation application, thereis very little potential for confusion. Thenumber of facilities currently equippedto conduct these tests is extremelysmall, which further diminishes anyproblems associated with differences inthe test method.

One commenter states that, because ofsuch a tremendously costly retrofitprogram, all further developments withregard to new testing methods mustclearly avoid duplication orcontradiction of actions as described inthe proposed AD’s.

The FAA has revised paragraph (c) ofthe final rule to clarify the flame spreadtest method to be used to qualifyreplacement insulation blankets. Aspreviously discussed, this test method isadequately refined to qualify thesematerials for this AD.

Details of the Test Procedures

One commenter states that results oftests have shown that the thickness ofthe insulation has no impact on theperformance of the film under test.Therefore, the commenter suggests thatall samples be tested with two-inchthick insulation.

One commenter requests that the FAAdevelop specifications forenvironmental conditioning of samplessince the absence of such requirementswill significantly alter test results, inparticular for ignition and flame spreadsensitive materials such as facedinsulation.

The commenter states that theproposed pass/fail criteria, includingthe minimum 2-inch burn length and 0flame spread, are not easily measured oragreed upon. Several commenters statethat clearer pass/fail criteria are needed.One commenter states that subjectiveassessment of test results in small scalefire testing is a constant, ongoingproblem that should be avoided.

One commenter claims that the‘‘pilot’’ burner arrangement called out inthe FAA specification does not result inreproducible test results. Likewise, the‘‘pre-heat’’ time between specimens andthe time between sample insertion andflame application have not beendefined. The commenter prefers astandard design and operationconditions and is unclear why thestandard design has been modified.

The FAA does not agree that thecurrent test method lacksreproducibility. Tests conducted at theFAA Technical Center and at otherfacilities indicate that the test isreproducible and repeatable. The FAAconcurs with the commenter that adefined test protocol should be usedwhen testing replacement material. Theflame spread test method specified inthe final rule does include the pass/failcriteria, environmental conditioning,and test specimen thickness. Issues suchas the pilot burner arrangement will bethe subject of further refinement beforethe test method is adopted as aregulatory standard, but are adequatelydefined for this AD.

One commenter requests that the testprocedures include contaminatedinsulation blankets to simulate realworld conditions. The commenter statesthat testing of pristine material may notprovide sufficient assurance whenwithin a few years the thermal blanketswill be contaminated with solvents andother material. The FAA does notconcur. While ‘‘contamination’’ mightresult in either detrimental or improvedflammability performance,incorporation of generic

‘‘contamination’’ into a test requirementis not practical. Contamination isusually a localized phenomenon, andnot spread uniformly throughout theairplane. Replacing the existingmaterials with materials that will notpropagate a fire will confine a fire to thearea of contamination and shouldprevent the fire from becoming a hazard.As with any material installed on anairplane, it is the operator’sresponsibility to ensure that the airplaneremains in an airworthy condition.

The commenter further requests thatthe test procedures include ignition ‘‘bythese so-called, otherwise harmlesselectrical arcs.’’’ The commenter statesthat the likelihood of thermal blanketspropagating a fire will typically startwith an electrical arc. Therefore, theresistance to an arc-tracking KaptonTM

(i.e., polyimide) wire fire should beassessed. The commenter contends thatthis will give a clear indication of whatthe next flight crew might experience,rather than a Bunsen Burner or cottonswab test that doesn’t relate to the realworld conditions found on affectedairplanes.

The FAA does not concur with thecommenter’s request to includeelectrical arcing ignition in the testprocedures. Electrical arc tests wereused to identify the unsafecharacteristics of MPET in the course ofresearch. The test method required bythis AD is, in fact, a more severemeasure of the materials’ performance.There are materials that are notsusceptible to ignition by electricalarcing that will not pass the testrequired by this AD. Therefore, thereplacement of MPET insulationblankets in accordance with this ADwill address the commenter’s concern.

Approved Materials

Two commenters request that theFAA revise the proposed AD’s toinclude an expanded list of approvedfilms. Several commenters note thatKaptonTM film installed 25 years ago onModel L–1011 series airplanes hasproven to outperform TedlarTM andMylarTM films in FAA tests, whichmeasure the materials’ ability to holdback flames. Two commenters state thatall FAA testing, including burnthroughtesting, have shown polyimide films tobe superior. In addition, FAAAdministrator, Jane Garvey, specificallymentioned KaptonTM film as being amaterial that would be ‘‘grandfatheredin’’ in an October 14, 1998,announcement.

Two commenters state that theproposed AD’s appear to preclude theuse of polyimide (KaptonTM) insulation



covering film that has passed the newRadiant Panel Test.

The FAA does not concur with thecommenters’ request to revise NOTE 4of the AD to include additional films.Except for the metallized TedlarTM

cover mentioned in NOTE 4 of the AD,currently, no other film has successfullypassed the flammability testing in amanner approved by the Manager, LosAngeles ACO. However, the FAA isaware of various film materials thatcould be found to be acceptablereplacement materials for MPET. Oncethese materials have successfully passedthe flammability testing specified in theAD, they must be approved by theManager, Los Angeles ACO. In additionto the flammability requirements, thematerial must be shown to meet allother applicable airworthinessrequirements. The FAA Administratordid make an announcement in October1998 that KaptonTM would be‘‘grandfathered,’’ and that the FAAwould not require that material to bereplaced once is was installed.However, that announcement was madeprior to the issuance of the NPRM forthis final rule. This AD does NOTrequire KaptonTM to be replaced once itis installed; however, it does requiretesting and approval of any material,including KaptonTM.

One commenter requests that the FAArevise NOTE 4 of the proposed AD’s toread ‘‘[t]he metallized Tedlar coversspecified in the service bulletins mustbe tested to demonstrate compliancewith the requirements of paragraph (c)of this AD.’’ The commenter disagreeswith the characterization that aparticular cover material is consideredacceptable with the requirements ofparagraph (c) of the proposed AD’s. Thecommenter states that the ThermalAcoustic Task Group, which wasorganized by the Fire (Safety) TestBranch of the FAA Technical Center todevelop the new flammabilityrequirements, did not begin to discussthe procedures for demonstratingcompliance until a seminar was held onSeptember 13 and 14, 1999. Because therelease date of the NPRM’s was beforethe seminar, no material could havebeen specified to be in compliance withthe requirements of paragraph (c) of theNPRM’s. The commenter states that, atthe time of publication of the proposedAD’s, compliance materials andmethods had not yet been submittedunder a Test Plan, conformityinspection of samples had not beencompleted, and properly witnessedtesting had not taken place.

The FAA does not concur with thecommenter’s request to revise NOTE 4of the AD as it suggests. The material

that is listed in the service bulletins hasbeen found acceptable by the FAA andwas tested at the FAA Technical Centerin a manner approved by the FAA, priorto the September seminar. The purposeof the seminar was not to develop testmethods, but to introduce the method tothe interested segment of the industry.Therefore, the timing of the seminar hasno bearing on the approval status of thematerial. No change to the final rule isnecessary.

Replacement Material ApprovalProcess

One commenter notes that under theheading ‘‘Differences Between theProposed AD and Service Bulletins’’ inthe preamble of the NPRM’s, it states‘‘* * * Only one of the two insulationblanket film materials specified in theservice bulletins has successfully passedthe testing of the ASTM flammabilitystandard and has been found to be anacceptable replacement material for theMPET-covered insulation blankets.Other film material, such as certainpolyimide and fluoropolymercomposites, also have been successfullytested to ASTM E648 and could befound to be acceptable for compliancewith the requirements of this proposedAD if presented to the FAA forapproval. These materials are not listedin the service bulletins describedpreviously.’’ The commenter claims thatthe original equipment manufacturer(OEM) and certain operators areinterpreting this statement as requiringa full Part Manufacturing Approval(PMA) and Supplemental TypeCertificate (STC) approval process forblankets using films not in thereferenced McDonnell Douglas servicebulletins.

One commenter states that other newmaterials besides KaptonTM will becomeavailable in the near future for use asinsulation coverings, and that the PMA/STC process is not designed for norsuited for purely materials testing. Thecommenter contends that using thisprocess would add a great deal ofunnecessary cost to the current approvalprocess for new materials. Anothercommenter requests that the proposedAD be revised to include languagedescribing a clear and abbreviatedapproval process for blankets utilizingnew and less flammable materials.

The FAA does not concur with thecommenter’s request to includelanguage describing the process forapproval of replacement insulationblankets utilizing new and lessflammable materials. The FAA approvalprocess of replacing materials/installations is well established andknown. Design approval can be obtained

by an STC or PMA. It is theresponsibility of the operators andmodifiers to obtain such approvals forany proposed materials under paragraph(c) of the AD. The FAA may approverequests for AMOC’s, such as alternativeblanket installation, under theprovisions of paragraph (e) of this AD ifsufficient data are submitted tosubstantiate that such a design changewould provide an acceptable level ofsafety.

The FAA has determined that anadequate supply of approvedreplacement materials will be availableto comply with this AD in the timespecified. Operators that choose todevelop new or different materials mustplan accordingly and obtain approval aspreviously stated. While the PMA orSTC process may not seem to be costeffective for some operators, it is theproper approval method to assure allairworthiness standards are met.

Insulation Material on Other AircraftOne commenter is not clear if the

material used today on other Boeingairplanes is able to pass ASTM E648.The same commenter also states that theproposed AD’s require full replacementof only MPET. The commenter is notclear what the rationale behind thisdecision is.

As discussed in the NPRM’s, theseAD’s are intended to correct an unsafecondition by replacing MPET insulationblankets. MPET film differs from otherfilms in use in that it is susceptible topropagation of a fire from a smallignition source. Other films, while notnecessarily meeting the proposed testrequirements, do not have thissusceptibility. It is the susceptibility tosmall ignition sources that creates theunsafe condition. New standards forinsulation materials in general may besimilar to the requirements of this AD,but will be used to upgrade the level ofsafety, and not correct an unsafecondition.

BurnthroughSeveral commenters request that the

FAA revise the proposed AD’s to makeclear that airlines are permitted toinstall insulation that meets aburnthrough protection standard. Twocommenters state that the proposedAD’s appear to preclude the use ofCurlon as a substitute for fiberglass toachieve burnthrough performance. Onecommenter states that Curlon materialand many other materials recentlydeveloped could easily andeconomically provide double the levelof protection of the current burnthroughtime (i.e., four minutes). Although theproposed AD’s do not address the



burnthrough safety threat, thecommenters want to take thisopportunity to achieve this importantsafety advance when replacing theinsulation. The commentersreemphasize that this would simply bereinforcing the October 1998announcement that Curlon would beone of the materials ‘‘grandfathered in,’’if operators proceeded to install itvoluntarily.

Two commenters request that theFAA revise the proposed AD’s toinclude requirements for burnthroughprotection from fuel fires on the groundfor all affected airplanes. Thecommenters state that replacement offlammable insulation is an opportunityto install burnthrough protection. Onecommenter states that this should be thetime to push the industry, as was donewith the heat release requirements forinterior materials a few years ago.Materials were not even available tomeet the new FAA requirements, butthe industry ‘‘stepped up to the plateand we now are all safer as a result ofthis proactive approach.’’

The FAA does not concur with thecommenters’ requests to includeburnthrough requirements in the AD.While burnthrough protection isimportant to the overall fire resistanceof airplanes following an accident, theactions required by this AD are intendedto correct a known unsafe condition—insulation blankets constructed ofMPET. The FAA does not consider thatthe degree of burnthrough protectionprovided by currently installedinsulation constitutes an unsafecondition. Therefore, it would beinappropriate to issue an AD to requireimprovement in burnthroughprotection. The new replacementinsulation blankets required by this ADmeet the test method specified in thefinal rule, correct the identified unsafecondition, and provide the level ofsafety required by 14 CFR part 25. TheFAA encourages the installation ofmaterials that meet additional standardssuch as fuselage burnthroughprotection.

Trade NamesOne commenter opposes the use of

trade names in both the preamble andregulatory text of the proposed AD’s andconsiders such references to tradenames highly prejudicial to Chemfab,the manufacturer of Chemfilm. Thecommenter states that there is no needfor brand name product identificationand that this connotes not only FAAapproval of, but also preference for, theidentified product brand. Once theofficial ‘‘seal of approval’’ has beengranted through the rulemaking process,

other market entrants face a significantbarrier in gaining customer acceptancesimply because the identified producthas been ‘‘officially’’ sanctioned.

Because of the publication andcirculation of the proposed AD’s, twocommenters request that the FAA revisethe proposed AD’s to identify themanufacturer(s) and trade names ofinsulation blanket covering films thathave met FAA requirements specified inthe proposed AD’s.

The FAA does not concur with thecommenters’ request to reference othertrade name products in the final rules orto eliminate all references. TedlarTM andMylarTM are common trade names andthis is the clearest way for FAA tocommunicate with affected operators.Except for the one metallized TedlarTM

cover mentioned in NOTE 4 of the AD,currently, no other film has beenapproved by the Manager, Los AngelesACO. In addition, the airplanemanufacturer is planning to listmaterials, once they have been testedand approved by the FAA, in therevised service bulletins (discussedpreviously under the heading‘‘Inadequate Procedures andInformation in Referenced ServiceBulletin’’). Furthermore, the FAA findsthat trade names such as of MylarTM,KaptonTM, and TedlarTM are well knownand are accepted terminology inindustry. The reference of these tradenames in the AD’s are not, in any way,an FAA endorsement of those products.Therefore, no change to the final rule isnecessary.

Wiring

One commenter requests thatflammability requirements for thesources of ignition (i.e., the wiring) forthermal blanket fires be stricter than therequirements for thermal blanketsthemselves. The commenter states thatthe 60-degree flame test—the only testrequired by the FAA for the wiring oncommercial airplanes—should bereplaced immediately with the verticalflame test as a minimum requirement,and that every type of wire insulation inall airplanes should have to meet it.

The FAA does not concur. Thecurrent flammability standard for wiringhas not been determined to beinadequate. The actions required by thisAD are intended to address an identifiedunsafe condition, which is that MPET-covered insulation blankets cancontribute to the spread of a fire whenignition occurs from a small ignitionsource such as electrical arcing orsparking. As noted previously, the FAAhas a major program underway toaddress issues related to airplane wiring

and problems are being addressed asthey are identified.

Corrosion ProtectionOne commenter states that for Model

MD–11 series airplanes to be affordedthe same corrosion protection offered bythe OEM installation, any fabricatedblankets must meet the original typedesign. The existing CorrosionPrevention and Control Program (CPCP)requirements are based on theperformance of the insulation system.Any compromise or alteration willnecessitate changes to the CPCP. Manyinsulation blankets cannot be installedas they originally were due toinstallation of overlying structure.Therefore, deviations to the type designwill have to be approved by the OEMand FAA in the form of an AMOC. Theburden of these approvals will stress theresources of the OEM and FAA over theduration of the compliance period.

The FAA does not concur. The FAAis aware of the potential effects ofchanging insulation material has on thecorrosion protection of the affectedairplanes. The airplane manufacturerintends to take this into account so thatno change to the CPCP is required. Anyoperator or modifier also will berequired, under paragraph (e) of thisAD, to address any ramifications to theCPCP in any request for an AMOC.

Add New InspectionOne commenter requests that, if it is

determined that an insulation blanket isnot constructed of MPET during theaction required by paragraph (a) of theproposed AD’s, a visual inspection beconducted to detect fire damage,electrical arcing, discoloration, or otherphysical damage. The commenter alsorequests a visual inspection for possibleignition sources during routinemaintenance on airplanes not affectedby the proposed AD’s.

The FAA does not concur with thecommenter’s request to revise paragraph(a) of the final rule to include a visualinspection for possible ignition sources.If any evidence of fire damage is foundduring the subject inspection, operatorsare already required to investigate anddetermine the source of the problem.This is no different from any othermaintenance action that is performed bythe operators. It is not necessary toinclude any additional requirements inthis AD to accomplish this action.

Alternative Method of ComplianceOne commenter states that it has

developed a system whereby theexisting bagged insulation can beremoved from the airplane without thenecessity of interfering with wiring



harnesses or other unrelated systems.The commenter claims that its systemwould reduce the installation time ofthe proposed AD’s, reduce the cost ofcompliance, and reduce the remotechances of creating future related AD’scaused by the method of compliance.Another commenter states that it alsohas developed an insulation system thatworks around existing equipment andthus eliminates the need to removemuch of the equipment that is notnormally removed during heavymaintenance checks. The commenterclaims that its system is lighter inweight than the OEM insulation systemand will result in fuel savings.

One commenter agrees that theflammability/flame spread performanceof the MPET-covered insulationblankets should be improved, butquestions proposed AD’s that wouldrequire blanket replacement. Thecommenter states that this approachmay not be the only possible method ofaddressing the issue. This concept isespecially important considering thepotential negative consequences ofrequired airplane disassembly toaccomplish the blanket replacement.The commenter suggests that there maybe other options such as spray coatingsthat offer virtually equivalentperformance with little negative impact.

From these comments, the FAA infersthat the commenters are requesting thatthe final rules be revised to include thecommenter’s systems for replacing ormodifying the MPET insulationblankets. The FAA does not concur. Thecommenters did not provide anytechnical details for the FAA to make afinding. Paragraph (e) of the final rulecontains provisions for requestingapproval of an AMOC to address thesetypes of unique circumstances.

One commenter requests that the FAArequire installation of additional fireresistant material(s) between theinsulation blankets and any adjacentwires, wire bundles, or other potentialignition sources instead of removingand replacing MPET insulationblankets. The commenter also requeststhat the FAA consider this approach oneither a full or partial basis. Anothercommenter believes that fire resistantmaterial(s) in such a location wouldbetter promote the overall safety of theaffected airplanes.

The FAA acknowledges that thissuggestion may be a possible acceptablealternative to removing the existinginsulation blankets. However, no changeto the final rule is necessary. Underparagraph (e) of the AD, operators mayapply for the approval of an AMOC oradjustment of the compliance time thatprovides an acceptable level of safety.

CommunicationOne commenter requests that the FAA

have a public meeting regarding theproposed AD’s. The commenter statesthat, because many vendors are trying todevelop materials that meet the newFAA requirements, and the market priceof these materials seems to varydrastically at present, it just hasinsufficient information on newmaterials.

The FAA does not concur that apublic meeting regarding the proposedAD’s is necessary. Through the FAATechnical Center, the FAA has provideda forum to develop flammabilitystandards for insulation materials. Inaddition, the FAA is aware of a numberof meetings hosted by the airplanemanufacturer to provide information tooperators affected by the requirementsof this AD. The FAA is sensitive of thepublic’s concern with the fire safetyissues associated with this AD and isaware of the effects this AD will have onoperators. The FAA has determined thatan unsafe condition exists, and that theactions required by this AD arenecessary in order to ensure thecontinued safety of the affected fleet.

Extend Comment Period of NPRM’s,Delay Issuance of Final Rules, andWithdraw NPRM’s

For the reasons described above,several commenters request that theFAA do one or more of the following:(1) Extend the public comment periodfor the NPRM’s and supplementalNPRM’s; (2) delay issuance of the finalrules; or (3) withdraw the NPRM’s andcombine them with the draftburnthrough NPRM. (The FAA infersthat the commenters are referring to adraft NPRM relating to insulationblanket flammability. The FAAannounced its intention to develop newflammability standards for thermal/acoustic insulation in October 1998.This announcement included mentionof improved burnthrough protection.)

One commenter states that it is notuncommon, in the case of an ADrelating to issues not as complex as theproposed AD’s, for the FAA to allow 90days or more to comment. The 45-daycomment period of the proposed AD’sdoes not allow for proper understandingand evaluation on which to developreasonable comments.

The FAA does not concur with thecommenters’ request to extend thecomment period. On November 10,1999, the FAA issued supplementalNPRM’s to reopen the comment periodfor an additional 25 days to provideopportunity for public comment (thecomment period for the NPRM’s was 45days and closed on September 27,

1999). The FAA finds that the publichas had a reasonable opportunity tocomment on the substance of the AD’s.The FAA does not concur with thecommenter’s statement that it is notuncommon for the FAA to allow 90days or more for the public to commenton proposed AD’s. The standardcomment period is 45 days for NPRM’sand 25 days for supplemental NPRM’sin which the FAA has responsibility asthe State of Design of the affectedairplanes. A 90-day comment periodwould be uncommon.

As discussed above in ‘‘InadequateProcedures in Referenced ServiceBulletins,’’ the FAA also finds that it ispossible to accomplish the requirementsof this AD. Since the issuance of theNPRM’s, the airplane manufacturer, inconjunction with operators, hascompleted the prototype installations.Based on the results of theseinstallations, the airplane manufactureris developing revisions to the servicebulletins referenced in the AD’s toinclude detailed instructions foraccomplishment of the requiredreplacement. These revised servicebulletins are scheduled for completionin June 2000. Any new or revisedservice bulletins, among other items,will contain procedures to maintain/testthe integrity of the wiring afteraccomplishment of the replacement ofany MPET insulation blanket. Theserevised service bulletins will beapproved as an AMOC for therequirements of this AD.

The FAA does not concur with thecommenter’s request to delay issuanceof the final rules. These revised servicebulletins are scheduled for completionin June 2000. The FAA has determinedthat, while physically challenging, theactions required by the AD can beaccomplished within the 5-yearcompliance time, and that the actionsare warranted to address an identifiedunsafe condition.

In support of its request to withdrawthe NPRM’s, one commenter contendsthat other rulemaking in developmentby the FAA may eventually affect theairplanes covered by this AD, therebyrequiring two extensive modifications.

The FAA does not concur with thecommenter’s request to withdraw theNPRM’s and combine them with thedraft burnthrough NPRM. Any otherregulatory action to raise the level ofsafety would have to be justified andsubject to public comment. The FAAdoes not anticipate requiring airplanesto be modified twice as a result of futureactions. The actions required by this ADare intended to correct an identifiedunsafe condition by removing MPETinsulation blankets from airplanes



affected by these AD’s. These actions arenot intended to provide a generalupgrade to the current level of safetyspecified in the airworthinessregulations. Therefore, the actionsrequired by these AD’s are warranted.

One commenter disagrees thatprototyping efforts are necessary todetermine the feasibility of therequirements of the proposed AD’s anddisagrees that issuance of the proposedAD’s should be delayed. The commenterstates that it is in the process ofprototyping the insulation retrofit onseveral affected airplanes. Thecommenter expects the prototyping tobe completed in 6 weeks (thecommenter’s letter was received by theFAA on September 27, 1999). The FAAconcurs with the commenter thatissuance of the final rules should not bedelayed. As discussed previously, theFAA has participated in the prototypingspecified by the commenter, and thatprototyping effort has been completed.

Cost Estimates

Several commenters state that theFAA ‘‘grossly’’ underestimated the costsassociated with accomplishing therequirements of the proposed AD andprovided their cost estimates. Two othercommenters provided cost estimatesthat were less than those provided inthe NPRM’s.

The FAA concurs that the costestimates specified in the NPRM’s wereunderestimated. The FAA based its costestimates on information that wasavailable at the time the NPRM’s wereissued. Since the issuance of theNPRM’s, the FAA has carefullyreviewed the information and costestimates provided by the commentersand the information obtained during theprototype exercises. The FAA haslearned that most Model DC–9–80 andMD–90–30 series airplanes do not haveMPET insulation blankets installed inthe nose section of the airplane. Also, anumber of airplanes do not have MPETinsulation blankets in the fuselage, buthave MPET insulation blankets only onthe air conditioning ducting. Theairplane manufacturer will be makingthis information available when theservice bulletins are revised, asmentioned above. In light of thesefindings, the FAA has revised the costestimates for the final rules, which issummarized below under the heading‘‘Regulatory Evaluation Summary.’’

Several commenters request that theFAA reevaluate the cost estimates oncethe prototype exercises are completed.As discussed previously, the FAA hasrevised the cost estimate of the finalrules based on the prototype exercises.

Several commenters state that theFAA should consider costs associatedwith accomplishing the requirements ofboth proposed AD’s (i.e., Rules Dockets99–NM–161–AD and 99–NM–162–AD) ,under Title II of the Unfunded MandatesReform Act of 1995.

The FAA did consider the total costsassociated with accomplishing therequirements of both NPRM’s for allaffected airplanes under the heading‘‘Regulatory Evaluation Summary’’ inthe preamble of the NPRM’s. A copy ofthe Preliminary Cost Analysis andInitial Regulatory Flexibility Analysisalso were included in each docket.These documents, along with the finaldocuments, are available for the publicto review.

ConclusionAfter careful review of the available

data, including the comments notedabove, the FAA has determined that airsafety and the public interest require theadoption of the rule with the changespreviously described. The FAA hasdetermined that these changes willneither increase the economic burdenon any operator nor increase the scopeof the AD.

Regulatory Evaluation SummaryTo determine the regulatory impact of

this AD, the FAA conducted a FinalCost Analysis and a Final RegulatoryFlexibility Analysis. In addition, theFAA assessed the impact of this AD oninternational trade and determinedwhether it must satisfy the requirementsof the Unfunded Mandate Reform Act.While a summary of these findings isreported in this preamble, a moredetailed discussion is included in theRules Docket for this AD.

Since the publication of the NPRM,the FAA has observed several prototypeexercises that involved the removal andreplacement of MPET insulationblankets. Information gained throughthese exercises has contributed togreater understanding by the FAA,operators, and manufacturer of thetechnical details and impacts of therequirements of this AD.

The FAA took account of the resultsof the prototype exercises, comments tothe NPRM’s, and other additionalinformation, and then adjusted itsestimates of the costs attributable to thisAD. Further, recent informationindicates that the count of affectedairplanes is 621 Model DC–9–80 seriesairplanes and 21 Model MD–90–30series airplanes. Specifics of theseadjustments are discussed below.

Several commenters indicate that theFAA underestimated the costs of thenew insulation material, labor hours

necessary for retrofitting, and lostpassenger revenue from retrofittingdowntime. With respect to labor andmaterial costs, the FAA contacted themajor material suppliers (one of whichwas the airplane manufacturer) andthree carriers that together operate 75%of the affected fleet. Information andestimates from these sources supportincreases both in the level of detail andin the levels of labor and material costsfor this adjusted estimate. Therefore, thelabor cost calculation methods used inthis AD differ from those used in theNPRM’s. The FAA has developed thelabor estimates for this AD usinginformation supplied by themanufacturer and affected operators toarrive at average values specific to therequirements of this AD. The FAAconsiders these values conservative.

The commenters expressdisagreement with the asset-basedapproach the FAA used in thePreliminary Cost Analysis to estimatethe cost of the loss of service of theairplanes during their retrofits. Thecommenters suggest that the estimate bemade on the basis of loss of per seatrevenue. There are two reasons why theFAA uses the asset-based approach.First, the FAA takes an industry-wideperspective in which a passenger whocannot be seated on an airplane that isout of service for compliance with thisAD can be seated on an airplane that isin service. On an industry-wide basis,no revenue will be lost. Second, thecontribution of a seat’s revenue tocorporate net income is subject tovariations in accounting, financial,marketing, and operational practice.

The FAA’s asset-based approachcenters on the financial ratio, overallcorporate rate of return, which wasreported by the operators and publishedby the Department of Transportation.This ratio is applied to the average valueof the assets lost to the service of theoperators and is adjusted for the averageperiod of time for which they are lostbecause of compliance. This approachassumes that operators maximize thevalue of their firms by optimizing themix and quantity of their assets.

Even though the FAA uses essentiallythe same ‘‘lost-revenue’’ method as thatin the supplemental NPRM’s, the FAAnevertheless did increase its estimatesof lost revenue by increasing thenumber of days out of service, reducingthe operating base year from 365 days toapproximately 320 days, and raising therate of return (9% is an average ofdomestic passenger and cargo operators’profit rates as estimated by theDepartment of Transportation’s Bureauof Transportation Statistics). All of theseadjustments raise the value of the



variables applied to the airplane assetvalues (i.e., $16.2 million per DC–9–80/MD–90–30).

The FAA has identified 621 ModelDC–9–80 and 21 MD–90–30 seriesairplanes that will be subject toretrofitting. Four of these airplanes haveMPET insulation installed throughout.Thirty-five of these airplanes haveMPET insulation installed only aroundair conditioning ducts. Six hundred andthree of these airplanes have MPETinstalled throughout except for the nose.These patterns of installation stronglyaffect the retrofitting costs for eachindividual airplane. The FAA final costsestimate reflects the cost of eachairplane when averaged for the totalDC–9–80/MD–90–30 affected fleet.

The foregoing results in the followingadjustments to the calculationspresented in the supplemental NPRM.

For Model DC–9–80 series airplanes,the preliminary estimates for labor,material, and lost service per airplanewere as follows: labor, $335,988;material, $27,021; and lost service,$20,416. The corresponding MD–90–30estimates were as follows: $385,560;$31,008; and $37,052.

The components of this adjustedestimate per airplane, for both ModelDC–9–80 and MD–9–30 series airplanes,are as follows: combined labor andmaterial, $479,921 (averaged as$628,184 for 4 airplanes, $73,156 for 35airplanes, and $502,547 for 603airplanes, as discussed above); and lostservice, $65,998. Overall, the adjustedestimates compare to the originalestimates as follows:

Original Adjusted

625 DC–9–80, each$383,000.

621 MD80s, each$545,919.

22 MD–90–30, each$454,000.

21 MD90s, each$545,919.

The adjusted estimate of the totalcosts of this AD over the five-yearretrofit period for all 644 affectednarrow-body airplanes is approximately$351.6 million or $288.6 milliondiscounted to present value. The totalimpact for all affected airplanes (i.e.,Model DC–9–80, MD–90–30 , MD–11,and DC–10 series airplanes) is 449.3million or 368.4 million discounted topresent value over the five yearcompliance time.

With respect to effects on smallentities, the Regulatory Flexibility Act(RFA) of 1980 establishes ‘‘as aprinciple of regulatory issuance’’ thatagencies shall endeavor, consistent withthe objective of the rule and ofapplicable statutes, to fit regulatory andinformational requirements to the sale

of the business, organizations, andgovernmental jurisdictions subject toregulation. To achieve that principle,the RFA requires agencies to solicit andconsider flexible regulatory proposalsand to explain the rationale for theiractions. The RFA covers a wide range ofsmall entities, including smallbusinesses, not-for-profit organizations,and small governmental jurisdictions.Agencies must perform a review todetermine whether a proposed or finalrule will have a significant economicimpact on a substantial number of smallentities. If the determination is that itwill, the Agency must prepare aregulatory flexibility analysis asdescribed in the RFA. However, if anagency determines that a proposed orfinal rule is not expected to have asignificant economic impact on asubstantial number of small entities,section 605(b) of the RFA provides thatthe head of the agency may so certifyand a regulatory flexibility analysis isnot required. The certification mustinclude a statement providing thefactual basis for this determination, andthe reasoning should be clear.

Of the operators affected by this AD,all but three are air carriers, none ofwhich is a small business. In two of theremaining cases, Model DC–9–80 seriesairplanes are owned for personal use.One Model DC–9–80 series airplane isoperated for non-carrier businesspurposes by a large corporation.Although the small business sizecriterion is met in the cases of the twoModel DC–9–80 series airplanes that areowned for personal use, two suchentities do not constitute a ‘‘substantialnumber’’ within the meaning of theRFA. Thus, pursuant to the RegulatoryFlexibility Act, 5 U.S. C. 605(b), theFAA certifies that this AD will not havea significant economic impact on asubstantial number of small entities.

The provisions of this AD will havelittle or no impact on trade for U.S.firms doing business in foreigncountries and foreign firms doingbusiness in the United States.

Finally, Title II of the UnfundedMandates Reform Act of 1995 (the Act),enacted as Public Law 104–4 on March22, 1995, requires each Federal agency,to the extent permitted by law, toprepare a written assessment of theeffects of any Federal mandate in aproposed or final agency rule that mayresult in the expenditure by State, local,and tribal governments, in the aggregate,or by the private sector, of $100 millionor more (adjusted annually for inflation)in any one year. Section 204(a) of theAct, 2 U.S.C. 1534, requires the Federalagency to develop an effective processto permit timely input by elected

officers (or their designees) of State,local, and tribal governments on aproposed ‘‘significant intergovernmentalmandate.’’ A ‘‘significantintergovernmental mandate’’ under theAct is any provision in a Federal agencyregulation that would impose anenforceable duty upon State, local, andtribal governments, in the aggregate, of$100 million (adjusted annually forinflation) in any one year. Section 203of the Act, 2 U.S.C. 1533, provides thatbefore establishing any regulatoryrequirements that might significantly oruniquely affect small governments, theagency shall have developed a plan that,among other things, provides for noticeto potentially affected smallgovernments, if any, and for ameaningful and timely opportunity toprovide input in the development ofregulatory proposals.

This AD does not contain any Federalintergovernmental or private sectormandate. Therefore, the requirements ofTitle II of the Unfunded MandatesReform Act of 1995 do not apply.

List of Subjects in 14 CFR Part 39Air transportation, Aircraft, Aviation

safety, Incorporation by reference,Safety.

Adoption of the Amendment

Accordingly, pursuant to theauthority delegated to me by theAdministrator, the Federal AviationAdministration amends part 39 of theFederal Aviation Regulations (14 CFRpart 39) as follows:

PART 39—AIRWORTHINESSDIRECTIVES

1. The authority citation for part 39continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13 [Amended]

2. Section 39.13 is amended byadding the following new airworthinessdirective:2000–11–01 McDonnell Douglas:

Amendment 39–11749. Docket 99–NM–161–AD.

Applicability: Model DC–9–81 (MD–81),DC–9–82 (MD–82), DC–9–83 (MD–83), DC–9–87 (MD–87) series airplanes; Model MD–90–30 series airplanes; and Model MD–88airplanes; manufacturer’s fuselage numbers995 through 2243 inclusive; certificated inany category.

Note 1: This AD applies to each airplaneidentified in the preceding applicabilityprovision, regardless of whether it has beenmodified, altered, or repaired in the areasubject to the requirements of this AD. Forairplanes that have been modified, altered, orrepaired so that the performance of therequirements of this AD is affected, the



owner/operator must request approval for analternative method of compliance inaccordance with paragraph (e) of this AD.The request should include an assessment ofthis AD; and, if the unsafe condition has notbeen eliminated, the request should includespecific proposed actions to address it.

Compliance: Required as indicated, unlessaccomplished previously.

To ensure that insulation blanketsconstructed of metallizedpolyethyleneteraphthalate (MPET) areremoved from the fuselage, accomplish thefollowing:

Inspection(a) Within 5 years after the effective date

of this AD, determine whether, and at whatlocations, insulation blankets constructed ofMPET, are installed. When markings are notvisible, the determination shall be made byusing known MPET material as a comparisonsample to assist in the identification.

Note 2: Insulation blankets that are markedwith ‘‘DMS 2072, Type 2, Class 1, Grade A;’’‘‘DMS 2072, Type 2, Class 1;’’ or ‘‘DMS 1996,Type 1;’’ are constructed of MPET.

Corrective Actions(b) For insulation blankets that are

determined not to be constructed of MPET,no further action is required by this AD.

(c) For insulation blankets that aredetermined to be constructed of MPET,within 5 years after the effective date of thisAD, replace the MPET insulation blanketswith new insulation blankets that have beenapproved by the Manager, Los AngelesAircraft Certification Office (ACO), FAA,Transport Airplane Directorate. The blanketsshall be replaced in accordance with theAccomplishment Instructions of McDonnellDouglas Service Bulletin MD–90–25–015,Revision 01, dated November 5, 1997 (forModel MD–90–30 series airplanes); orMcDonnell Douglas Service Bulletin MD80–25–355, Revision 01, dated November 5, 1997(for Model DC–9–80 series airplanes andModel MD–88 airplanes); as applicable. Thereplacement insulation blankets must beconstructed of materials tested in accordancewith Appendix 1 of this AD, or in accordancewith a method approved by the Manager, LosAngeles ACO.

Note 3: Although this paragraph allows upto 5 years for the required replacement, theFAA anticipates that operators will comply atthe earliest practicable maintenanceopportunity.

Note 4: Only one of the two metallizedTedlarTM covers specified in the service

bulletins has been shown to havesuccessfully passed the testing of theAmerican Society for Testing and Materials(ASTM) flammability standard and isconsidered acceptable for compliance withthe requirements of paragraph (c) of this AD.

Spares(d) As of the effective date of this AD, no

person shall install an MPET insulationblanket on any airplane.

Alternative Methods of Compliance(e) An alternative method of compliance or

adjustment of the compliance time thatprovides an acceptable level of safety may beused if approved by the Manager, LosAngeles ACO. Operators shall submit theirrequests through an appropriate FAA PMI,who may add comments and then send it tothe Manager, Los Angeles ACO.

Note 5: Information concerning theexistence of approved alternative methods ofcompliance with this AD, if any, may beobtained from the Los Angeles ACO.

Special Flight Permits(f) Special flight permits may be issued in

accordance with sections 21.197 and 21.199of the Federal Aviation Regulations (14 CFR21.197 and 21.199) to operate the airplane toa location where the requirements of this ADcan be accomplished.

Incorporation by Reference(g) The blankets shall be replaced in

accordance with the AccomplishmentInstructions of McDonnell Douglas ServiceBulletin MD–90–25–015, Revision 01, datedNovember 5, 1997; or McDonnell DouglasService Bulletin MD80–25–355, Revision 01,dated November 5, 1997; as applicable. Thisincorporation by reference was approved bythe Director of the Federal Register inaccordance with 5 U.S.C. 552(a) and 1 CFRpart 51. Copies may be obtained from BoeingCommercial Aircraft Group, Long BeachDivision, 3855 Lakewood Boulevard, LongBeach, California 90846, Attention: TechnicalPublications Business Administration, Dept.C1–L51 (2–60). Copies may be inspected atthe FAA, Transport Airplane Directorate,1601 Lind Avenue, SW., Renton,Washington; or at the FAA, TransportAirplane Directorate, Los Angeles AircraftCertification Office, 3960 ParamountBoulevard, Lakewood, California; or at theOffice of the Federal Register, 800 NorthCapitol Street, NW., suite 700, Washington,DC.

(h) This amendment becomes effective onJune 30, 2000.

Appendix 1.—Test for MaterialsReplacing Metallized PET ThermalAcoustical Insulation, Film February16, 2000

This test method is used to evaluate theflammability and flame propagationcharacteristics of thermal/acoustic insulationwhen exposed to both a radiant heat sourceand a flame.

(a) Definitions.(1) Thermal/Acoustic Insulation. Thermal/

acoustic insulation is defined as a material orsystem of materials used to provide thermaland/or acoustic protection. Examples includea film-covering material encapsulating a corematerial such as fiberglass or other battingmaterial and foams.

(2) Radiant Heat Source. The radiant heatsource is an air/gas fueled radiant heatenergy panel.

(b) Test Apparatus (as schematicallyshown in figure 1).

(1) Radiant Panel Test Chamber. Tests willbe conducted in the radiant panel testchamber as used in ASTM—Designation: E648. It is suggested that the test chamber belocated under an exhaust hood to facilitateclearing the chamber of smoke after each test.The radiant panel test chamber shall consistof an enclosure 55 inches (1400 mm) long by191⁄2 inches (500 mm) deep by 28 inches (710mm) above the test specimen. The sides,ends, and top shall be insulated with afibrous ceramic insulation such asKaowoolTM board. One side shall be providedwith an approximately 48 by 6 inch (1219 by152mm) draft tight, high temperature, heatresistant glass observation window, tofacilitate viewing the sample during testing.On the same side and below the window isa door which, when open, allows thespecimen platform to be moved out formounting or removal of test specimens. Thebottom of the test chamber shall consist of asliding steel platform, which has provisionsfor securing the test specimen holder in afixed and level position. The top of thechamber shall have an exhaust stack withinterior dimensions of 4 inches (102mm)wide by 15 inches (380 mm) deep by 12.5inches (318mm) high at the opposite end ofthe chamber from the radiant energy source.

(2) Radiant Heat Source. The radiant heatenergy source will be a panel of porousrefractory material mounted in a cast ironframe, with a radiation surface of 12 by 18inches (305 by 457mm). It shall be capableof operating at temperatures up to 1500°F(816°C (Figure 1).



(i) Radiant Panel Fuel System. The radiantpanel fuel will be propane (liquid petroleumgas—2.1 UN 1075). The panel fuel systemshall consist of a venturi-type aspirator formixing gas and air at approximatelyatmospheric pressure. Suitableinstrumentation will be necessary formonitoring and controlling the flow of fueland air to the panel. Instrumentation willinclude an air flow gauge, an air flowregulator, a gas pressure gauge, and arotameter for measuring gas flow.

(ii) Radiant Panel Placement. The panelwill be mounted in the chamber at 30 degreesto the horizontal specimen plane.

(3) Specimen Holding System.(i) The sliding platform serves as the

housing for test specimen placement. A 1⁄4inch (6.35mm) sheet of Durarocκa

¨, or other

non-combustible base, measuring 431⁄4inches by 121⁄2 inches (1098 by 317.5mm)will be placed in the open bottom (base) ofthe sliding platform. It is necessary to cut thenon-combustible base into two pieces forplacement in the bottom of the platform,since it will be supported by a 3⁄4-inch

(19.1mm) lip that extends around the bottomof the platform base. It is suggested that theshortest piece be placed at the end furthestfrom the radiant panel (figure 2). A 1⁄2 inch(13mm) piece of KaowooλTM board or otherhigh temperature material measuring 411⁄2 by81⁄4 inches (1054 by 210mm) will be attachedto the back side of the platform. This boardwill serve as a heat retainer and will protectthe test specimen from excessive preheating.The height of this board must not be too highsuch that it will impede the sliding platformmovement (in and out) of the test chamber.



(ii) The test specimen will be placedhorizontally on the non-combustible base. Astainless steel retaining frame (AISI Type 300UNA–NO8330), or equivalent, having athickness of 0.078 inches (1.98mm) and

overall dimensions of 443⁄4 by 123⁄4 inches(1137 by 320mm) with a specimen openingof 40 by 77⁄8 (1016 by 140mm) will be placedon top of the test specimen. The retainingframe will have two 1⁄2inch (12.7mm) holes

drilled at each end for positioning the frameto the two stud bolts at each end of thesliding platform (figure 3).

(iii) A securing frame (acting as a clampingmechanism) constructed of mild steel will beplaced over the test specimen. The securingframe overall dimensions are 421⁄2 by 101⁄2inches (1080 by 267mm) with a specimenopening of 391⁄2 by 71⁄2 inches (1003 by190mm). Hence, the exposed area of testspecimen exposed to the radiant panel is391⁄4 by 71⁄4 inches (996 by 184mm). Seefigure 4. It is not necessary to physicallyfasten the securing frame over the testspecimen due to the weight of the frameitself.

(4) Pilot Burner. The pilot burner used toignite the specimen is a commercial propane

venturi torch with an axially symmetricburner tip having a propane supply tube withan orifice diameter of 0.003 inches(0.076mm). The propane flow is adjusted toproduce a pencil flame blue inner conelength of 1⁄2 inch (13mm). There will be ameans provided to move the burner out ofthe ignition position so that the flame ishorizontal and at least 2 inches (50mm)above the specimen plane.

(5) Thermocouples. Three 24 AmericanWire Gauge (AWG) Type K (Chromel-Alumel) thermocouples will be installed inthe test chamber for temperature monitoring.All three are inserted into the chamber

through three small holes drilled through thetop of the chamber. One thermocouple isplaced 2 inches (51mm) from the end of theradiant panel and approximately 16 inches(406mm) above the test specimen. Thesecond thermocouple is placed 5 inches(127mm) from the first thermocouple andapproximately 16 inches (406mm) from thesample. The third thermocouple is located inthe chimney approximately 38 inches(965mm) above the specimen.

(6) Calorimeter. The calorimeter will be aone inch cylindrical water-cooled, total heatflux density, foil type Gardon Gage that has



a range of 0 to 5 BTU/ft2-second (0 to 5.6Watts/cm2).

(7) Calorimeter Calibration Specificationand Procedure.

(i) Calorimeter Specification.(A) Foil diameter will be 0.25±0.005 inches

(6.35±0.13mm).(B) Foil thickness will be 0.0005±0.0001

inches (0.013±0.0025mm).(C) Foil material will be thermocouple

grade Constantan.(D) Temperature measurement will be a

Copper Constantan thermocouple.(E) The copper center wire diameter will be

0.0005 inches (0.013mm).(F) The entire face of the calorimeter will

be lightly coated with ‘‘Black Velvet’’ painthaving an emissivity of 96 or greater.

(ii) Calorimeter Calibration.(A) The calibration method will be by

comparison to a like standardized transducer.

(B) The standardized transducer will meetthe specification given in paragraph (6).

(C) It will be calibrated against a primarystandard by the National Institute ofStandards and Technology (NIST).

(D) The method of transfer will be a heatedgraphite plate.

(E) The graphite plate will be electricallyheated, have a clear surface area on each sideof the plate of at least 2 by 2 inches (51 by51mm), and be 1⁄8 inch ±1⁄16 inch thick (3.2±1.6mm).

(F) The 2 transducers will be centered onopposite sides of the plates at equal distancesfrom the plate.

(G) The distance of the calorimeter to theplate will be no less than 0.0625 inches(1.6mm), nor greater than 0.375 inches(9.5mm).

(H) The range used in calibration will beat least 0–3.5 BTUs/ft2 second (0–3.9 Watts/

cm2) and no greater than 0–5.6 BTUs/ft2second (0–5 Watts/cm2).

(I) The recording device used must recordthe 2 transducers simultaneously or at leastwithin 1⁄10 second of each other.

(8) Calorimeter Fixture. With the slidingplatform pulled out of the chamber, install a2-rail fixture that has a travel range of 401⁄4inches (1022mm) over the sliding platform.The dimension between the 2 rails is 211⁄16

inches (68mm). The rail fixture is screwedinto the sliding panel, such that it is alwaysdirectly under the geometric center of theradiant panel (figure 4). Push the platforminto the chamber and insert the calorimeter.The calorimeter, which is mounted in aninsulated housing, fits in the rail opening buthas enough clearance such that it may bemoved along the rail for heat flux readings.The top surface of the calorimeter must belevel with the rails.

(9) Instrumentation. A calibrated recordingdevice with an appropriate range or acomputerized data acquisition system will beprovided to measure and record the outputsof the calorimeter and the thermocouples.The data acquisition system must be capableof recording the calorimeter output everysecond.

(10) Timing Device. A stopwatch or otherdevice, accurate to ±1second/hour, will beprovided to measure the time of applicationof the pilot burner flame.

(c) Test Specimens.(1) Specimen Preparation. A minimum of

three test specimens will be prepared andtested.

(2) Construction. Cut a piece of corematerial such as foam or fiberglass. Iffiberglass is used, cut the material 431⁄2 (±1⁄4)inches long (1093mm) (±6.3mm) by 121⁄2inches (305.1mm) wide. If using foam, cutthe material 411⁄4 inches (1039mm) by 11inches wide (279mm) by 11⁄2 inches (381mm)

high. Cut a piece of film cover material (ifused) large enough to cover the core material.It is permissible to staple the film cover atthe ends, as they are not exposed to theradiant heat source. A piece or pieces of aninorganic/inert material such as KaowooλTM

or Marinitε TM board may be placed in thebottom of the sliding platform holder if thesample is not thick enough to be level withthe top of the sliding platform. The specimenthickness must be of the same thickness asinstalled in the airplane.

(d) Specimen Conditioning. The specimenswill be conditioned at 70 ±5°F (21 ±2°C) and55%±10% relative humidity for a minimumof 24 hours prior to testing.

(e) Calibration.(1) With the sliding platform out of the

chamber, install the rail fixture. Push theplatform back into the chamber, install thecalorimeter (in its housing), and move thecalorimeter to the ‘‘zero’’ position (figure 5).Close the bottom door located below the

sliding platform. The centerline of thecalorimeter is 17⁄8 inches (46mm) from theend of the sliding platform. This will be the‘‘zero’’ position. The distance from the centerof the calorimeter to the radiant panel surfaceat this point is 7.5 inches ±1⁄8 (191 mm ±3).

(i) Prior to igniting the radiant panel,ensure that the calorimeter face is clean andthat there is water running through thecalorimeter.

(2) Ignite the panel. Adjust the fuel/airmixture to achieve 1.5 BTUs/ft2–second±0.025 BTUs/ft2–second (1.9 Watts/cm2±0.025 Watts/cm2) at the ‘‘zero’’ position.Allow the unit to reach steady state (this maytake up to 1 hour). The pilot burner is offduring this time. The temperature asmeasured by the thermocouple closest to thepanel (forward) is approximately 1100°F(600°C). The temperatures recorded bythermocouples 2 and 3 ( thermocouple 3located in chimney) are approximately 430°F(230°C) and 300°F (135°C), respectively.



(3) After steady-state conditions have beenreached, move the calorimeter 2 inches(51mm) from the ‘‘zero’’ position and record

the heat flux. Allow a minimum of 30seconds at each position for the calorimeter

to stablize. Record at least 10 positions.(Figure 6 depicts a calibration profile.)

(4) It is not necessary to run a full heat fluxcalibration (minimum of 10 positions) eachtime the chamber is powered on. It isrequired that a heat flux measurement betaken at the ‘‘zero’’ position at the start of thetest period (e.g., each morning) to ensure thatthe 1.5 BTU/ft2–second (1.9 Watts/cm2)requirement be met. A full calibration shouldbe run periodically.

(5) Open the bottom door, pull out thesliding platform, and remove the calorimeterand rail fixture.

(f) Test Procedure.(1) Ignite the pilot burner. Ensure that it is

at least 2 inches (51mm) above the top of theplatform. The burner must not contact thespecimen until the test begins.

(2) Place the test specimen in the slidingplatform holder. Ensure that the test samplesurface is level with the top of the platform.At ‘‘zero’’ point, the specimen surface is 71⁄2inches ±1/8 (191mm ±3) below the radiantpanel.

(3) With film/fiberglass assemblies, it maybe necessary to puncture small holes in thefilm cover to purge any air inside. Thisallows the operator to maintain the propertest specimen position (level with the top ofthe platform). The holes should be made inthe sides and/or the corners of the testspecimen using a needle-like tool.

(4) Place the retaining frame and thesecuring frame over the test specimen.

(5) A small mark should be placed on the‘‘zero’’ point.

(6) Immediately push the sliding platforminto the chamber and close the bottom door.

(7) Bring the pilot burner flame intocontact with the center of the specimen suchthat the center line of the flame impinges onthe ‘‘zero’’ point and simultaneously start thetimer. The burner flame impinges the sampleat an angle of approximately 20 degrees withthe horizontal (front of the sliding platform).

(8) Leave the burner in position for 15seconds and then remove to a position atleast 2 inches (51mm) above the specimen.

(g) Report.(1) Identify and describe the specimen

being tested.(2) Report any shrinkage or melting of the

test specimen.(3) Report the Burn length(4) Report Extinguishing Time(h) Requirements.(1) During burner application, no flaming

is allowed to propagate more than 2 inches(50.8mm) along the sample (to the left infigure 1) of the centerline of the flame.

(2) There shall be no flaming of the testsample after pilot burner removal.



Issued in Renton, Washington, on May 19,2000.John J. Hickey,Manager, Transport Airplane Directorate,Aircraft Certification Service.

[FR Doc. 00–13149 Filed 5–25–00; 8:45 am]BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99–NM–162–AD; Amendment39–11750; AD 2000–11–02]

RIN 2120–AA64

Airworthiness Directives; McDonnellDouglas Model DC–10–10F, DC–10–15,DC–10–30, DC–10–30F, and DC–10–40Series Airplanes, and Model MD–11and –11F Series Airplanes

AGENCY: Federal AviationAdministration, DOT.ACTION: Final rule.

SUMMARY: This amendment adopts anew airworthiness directive (AD),applicable to certain McDonnellDouglas Model DC–10–10F, DC–10–15,DC–10–30, DC–10–30F, and DC–10–40series airplanes, and Model MD–11 and–11F series airplanes, that requires adetermination be made of whether, andat what locations, metallizedpolyethyleneteraphthalate (MPET)insulation blankets are installed, andreplacement of MPET insulationblankets with new insulation blankets.This amendment is prompted by reportsof in-flight and ground fires on certainairplanes manufactured with insulationblankets covered with MPET, whichmay contribute to the spread of a firewhen ignition occurs from smallignition sources such as electrical arcingor sparking. The actions specified bythis AD are intended to ensure thatinsulation blankets constructed ofMPET are removed from the fuselage.Such insulation blankets couldpropagate a small fire that is the resultof an otherwise harmless electrical arcand could lead to a much larger fire.DATES: Effective June 30, 2000.

The incorporation by reference ofcertain publications listed in theregulations is approved by the Directorof the Federal Register as of June 30,2000.

ADDRESSES: The service informationreferenced in this AD may be obtainedfrom Boeing Commercial AircraftGroup, Long Beach Division, 3855Lakewood Boulevard, Long Beach,California 90846, Attention: Technical

Publications Business Administration,Dept. C1–L51 (2–60). This informationmay be examined at the FederalAviation Administration (FAA),Transport Airplane Directorate, RulesDocket, 1601 Lind Avenue, SW.,Renton, Washington; or at the FAA,Transport Airplane Directorate, LosAngeles Aircraft Certification Office,3960 Paramount Boulevard, Lakewood,California; or at the Office of the FederalRegister, 800 North Capitol Street, NW.,suite 700, Washington, DC.FOR FURTHER INFORMATION CONTACT:Robert Stacho, Aerospace Engineer,Systems and Equipment Branch, ANM–130L, FAA, Transport AirplaneDirectorate, Los Angeles AircraftCertification Office, 3960 ParamountBoulevard, Lakewood, California90712–4137; telephone (562) 627–5334;fax (562) 627–5210.SUPPLEMENTARY INFORMATION: Aproposal to amend part 39 of the FederalAviation Regulations (14 CFR part 39) toinclude an airworthiness directive (AD)that is applicable to certain McDonnellDouglas Model DC–10–30 and –30Fseries airplanes, and Model MD–11 and–11F series airplanes was published asa notice of proposed rulemaking(NPRM) in the Federal Register onAugust 12, 1999 (64 FR 43963). Asecond proposal that was identical tothe NPRM, except that it affectedadditional airplanes, was published as asupplemental NPRM on November 17,1999 (64 FR 62615). Those actionsproposed to require that a determinationbe made of whether, and at whatlocations, metallizedpolyethyleneteraphthalate (MPET)insulation blankets are installed, andreplacement of MPET insulationblankets with new insulation blankets.

Since the issuance of those NPRM’s,the FAA has observed severalprototyping exercises that involved theremoval and replacement of MPETinsulation blankets. The informationobtained from these exercises assistedthe FAA, operators, and manufacturer inunderstanding the technical details andimpact of the requirements of this AD.Certain aspects of these prototypeexercises will be discussed in the FAA’sresponse to the comments received fromthe NPRM’s.

Comments

Interested persons have been affordedan opportunity to participate in themaking of this amendment. Dueconsideration has been given to thecomments received.

The FAA has received comments inresponse to the NPRM’s andsupplemental NPRM’s to Rules Docket

No.’s. 99–NM–161–AD [applicable tocertain McDonnell Douglas Model DC–9–81 (MD–81), DC–9–82 (MD–82), DC–9–83 (MD–83), DC–9–87 (MD–87) seriesairplanes; Model MD–90–30 seriesairplanes; and Model MD–88 airplanes]and 99–NM–162–AD (applicable tocertain McDonnell Douglas Model DC–10–30 and –30F series airplanes, andModel MD–11 and –11F seriesairplanes). Because in most cases theissues raised by the commenters aregenerally relevant to both NPRM’s, eachfinal rule includes a discussion of allcomments received.

Support for Proposed AD’sSeveral commenters support the

intent of the proposed AD’s; however,they request that some changes be made(discussed later).

Unsafe ConditionOne commenter states that, because

the MPET insulation blankets onlypropagate the flame and are not thesource of the flame, the proposed AD’sshould address the unsafe condition(i.e., source of the flame) rather thanpreviously certified material (which metthe flammability standard at one time)that is not creating the unsafe condition.The FAA does not concur. MPETinsulation blankets, when ignited froma small ignition source, such as anelectrical arc, can contribute to thespread of a fire. Such insulationblankets could propagate a small fireand lead to a much larger fire. Potentialignition sources exist in many areas ofthe affected airplanes. It is extremelydifficult to determine where allpotential ignition sources are. Toprovide the level of safety that isexpected by the public for transportcategory airplanes, insulation blanketsconstructed of MPET must be removed.Therefore, the FAA finds that it hasproperly identified the unsafe condition(i.e., insulation blankets constructed ofMPET) addressed by these AD’s.

The same commenter suggests that thesubject blankets be handled as ‘‘attritionreplacements,’’ as intended in theoriginal McDonnell Douglas servicebulletins. The commenter states that,since cabin interior flammability hasbeen addressed already to a large extentby the FAA, MPET insulation blanketscould be treated comparably, and thus,integrated into the overall interiormaterials requirements. (The FAA infersthat the commenter is referring to theprovisions in 14 CFR section 121.312related to ‘‘substantially completereplacement of the cabin interior.’’)These requirements not only mandatestricter new standards, but allow olderairplane interiors to remain in service


department of transportation - faa fire safety · the faa, operators, and manufacturer in...

Documents