july 2006 flight airworthiness support technology · best operator of a small fleet of six a330s...

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The Airbus A380 is leaps ahead. Surpassing current levels of efficiency andwith state-of-the-art cabin design, it embodies 30 years of non-stop innovationAirbus, setting the standards.

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One giant leap.

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J U L Y 2 0 0 6 38

Just happened

Customer Servicesevents

SPARES, SUPPLIER SUPPORT & WARRANTYSYMPOSIUMATHENS, GREECE13 - 16 FEBRUARY 2006Over 70 customer represen-tatives from Europe andAfrica and 30 suppliercompanies attended thesymposium titled ‘Workingtogether in partnership’.Airlines, MROs and majorsuppliers exchanged viewson how to optimize mainte-nance and operationalcosts. Airbus presented theAirbus Modular SparesServices (AMSS), a fullyflexible supply chain serv-ices approach, enablingcustomers to focus on theirindividual core business. Airbus Supplier monitor-ing recognized the progressmade on supplier perform-ance while continuousimprovement initiativeswith BFE and engines sup-pliers were presented tocustomers.Airbus Warranty furtherdemonstrated via an on-site classroom the capaci-ties of its all-new on-lineservices, which enhanceefficiency in everyone’soperations whilst ensuringprotection of customers’rights.

A300/A310 ADVANCEDCOCKPIT PROGRAMME TOULOUSE, FRANCE22 - 23 MARCH 2006A two-day briefing forA300/A310 operatorswas held in March 2006in Toulouse to detail thisprogramme which con-siders aircraft operationuntil the year 2025 andbeyond. With this ad-vanced cockpit, airlineswould benefit from a sig-nificant reduction inmaintenance costs, theFMS2 (Flight Manage-ment System) and thenew ATM (Air TrafficManagement) capabilitieswill allow trajectory prediction and optimiza-tion, resulting in signifi-cant fuel saving. There was also a reviewof the current in-servicerequirement for enhance-ment of the existingFlight Management Sys-tem memory and dataloading characteristics. Though the AdvancedCockpit is the long-termcomprehensive solutionto this, it was announcedthat feasibility studies toinvestigate a shorter termsolution are underway,further feedback will begiven during the thirdquarter of 2006.

A330/A340 FAMILYTECHNICAL SYMPOSIUMSUN CITY, SOUTH AFRICA28 MAY - 2 JUNE 2006The latest developmentsin support services fromAirbus were explained,including FAIR (an inter-active forum for resolu-tion of technical issues),AirN@v and e-Cataloguedevelopments, as well asthe new concept forService Bulletins. The airline caucus identi-fied issues to be addressed,which were landing gear,design service goal exten-sion and fuel tank contam-ination. For non-technicalissues, vendor manage-ment, single source suppli-ers and AD traceability bypart number changes werehighlighted. Also request-ed were more frequentupdates outside sympo-siums. Operational Excellenceawards were presented.Gulf Air was awarded asbest operator of a smallfleet of six A330s andKorean Air was awarded astop operator of a large fleetof 19 A330s. ChinaAirlines with a fleet ofseven A340s and Luft-hansa German Airlineswith 39 A340s were award-ed for their excellence.South African Airwaysreceived the award as bestA340-600 operator.

HUMAN FACTORS SYMPOSIUMMOSCOW, RUSSIA14 - 16 JUNE 2006The 22nd Human FactorsSymposium took placewith the theme of:‘Human Factors as a corevalue at Airbus’. The sym-posium encompassed HFstrategy, HF training,operations and threat anderror management inflight operations, ATC andmaintenance. Particular importance wasgiven to the HumanFactors Toolkit Project,which is intended to rec-oncile Human FactorsTheory with operationalguidance. The event was sponsoredby ICAO and IAC(Interstate Aviation Com-mittee) of the CIS(Commonwealth ofIndependent States).

Coming soonTRAINING SYMPOSIUM, SAN FRANCISCO, USA, 2 - 5 OCTOBER 2006After an outstanding event in Bangkok in December 2004, Airbus is pleased to announce the eighth dynamic and highly informative forum dedicated to the Airbus international training scene. This two yearly event provides airlinetraining professionals with a unique opportunity. Whether the focus is on flying, cabin safety or aircraft maintenance, participants will get the latest status of all Airbustraining programmes, technologies, techniques and perspectives and will share their Airbus training experience withthe industry’s most senior players. Separate but integrated conference streams covering pilot training, cabin crew train-ing, maintenance training and simulation & training technologies will complement an exhibition featuring the latestdevelopments in these fields. Invitations were sent in June 2006.

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This issue of FAST has been printed on paperproduced without using chlorine, to reducewaste and help conserve natural resources.Every little helps!

Publisher: Bruno PiquetEditor: Kenneth Johnson

Graphic Designer: Agnès Massol-Lacombe

Authorization for reprint of FAST articles should be requested from the editor at the FAST e-mail address given below

Customer Services Communications Tel: +33 (0)5 61 93 43 88

Fax: +33 (0)5 61 93 47 73E-mail: [email protected]

Printer Escourbiac

FAST may be read on Internet http://www.content.airbusworld.com/SITES/Customer_services/index.html

under Customer Services/Publications

ISSN 1293-5476

Airbus Customer Services

© AIRBUS S.A.S. 2006. All rights reservedNo other intellectual property rights are granted by the delivery of this Magazine than

the right to read it, for the sole purpose of information. This Magazine and its content shall not be modified and its images shall not be reproduced without prior written consent of Airbus.

This Magazine and the material it contains shall not, in whole or in part, be sold, rented, distributedor licensed to any third party. The information contained in this Magazine may vary over time

because of future factors that may affect the accuracy of information herein. Airbus assumes noobligation to update any information contained in this Magazine. When additional information

is required, Airbus S.A.S. can be contacted to provide further details. Airbus, its logo and productnames are registered trademarks. Airbus S.A.S. shall assume no liability for

any damage in connection with the use of this Magazine and of the materials it contains,even if Airbus S.A.S. has been advised of the likelihood of such damages

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Photographs: exm company: Hervé Goussé and Philippe Masclet

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Performance monitoring of IFE systemsProposal for the future from Emirates Airline perspectiveMahmood Ameen and Vijay Rathnam

Performance monitoring of IFE systemsAirbus vision for the futureMarc Virilli

The A380 maintenance programme is born!A major success by all involvedChristian Delmas and Régis Broutee

Hypoxia - An invisible enemyCabin depressurization effectson human physiologyHartwig Asshauer

Fuel contaminationPrevention and maintenance actionsChristopher McGregor

Fuel contaminationPart II

Customer ServicesAround the clock... Around the world

Cover: See A380 maintenanceprogramme article on page 11

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PERFORMANCE MONITORING OF IFE SYSTEMS - PROPOSALS FOR THE FUTURE FROM EMIRATES AIRLINE PERSPECTIVE

Today’s In Flight Entertainment (IFE) systemsinstalled in many wide body aircraft are undoubted-ly some of the most complex systems engineeringprofessionals have ever designed and developed.On average, well over 2,000 Line ReplaceableUnits (LRUs) are installed and linked by networksonboard the aircraft. These systems have a corehardware platform layer, a network layer, an oper-

ating system layer, a core software layer, an appli-cation layer, a BITE (Built-In Test Equipment)reporting layer and a Graphic User Interface(GUI) layer. These are augmented by databasesthat identify an airlines chosen cabin/seat config-uration, overhead display configuration andapplicable media storage and reproducing devices(video, audio and games).

Vijay RathnamProjects Engineer, IFE programsEmirates Engineering ProjectsEmirates, Dubai, UAE

Mahmood AmeenVice President

Emirates Engineering ProjectsEmirates, Dubai, UAE

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There are many parties involved inthe life cycle of IFE developmentand maintenance. The airlinesengineering projects team, which isthe focal point within an airline,works with other departments suchas in-flight services, catering, IFEmedia services, maintenance engi-neering, procurement, spares plan-ning and cabin/IFE maintenanceteams. Externally, the projectsteam interfaces with OEMs(Original Equipment Manufactu-rers - Airbus or Boeing), IFE ven-dors, seat vendors, galley vendors,Airshow/ Camera and other thirdparty suppliers. Typically, thedevelopment cycle takes well overtwo years from the kick-off stage todelivery of the first aircraft withoperational and certified IFE.

Consider the following scenario:You have worked tirelessly for twoyears along with other teams tosuccessfully develop and deliver anIFE system, which is fully installedand operational. The responsibilitydoes not stop here. If all goes well,the first revenue flight with passen-gers is successful. Over a period ofseveral months after entry into ser-vice, as is common with complexsystems ; you find a certain num-ber of problems. On Mondaymorning, your Senior VicePresident asks your team for inputon how the IFE is performing inservice. You hastily review the in-service logs, pore overMTBUR/MTBF data, scan and res-can in-service problems organized

according to priority/ criticality,and review technical logs.Moreover, if you are lucky, youmay be apprised of the customer’sfeedback.

In the end, what you have compiledcan best be described as a mixedbag of information, and you havecome to realize that the report stilldoes not represent how the IFE per-formed throughout flight. In addi-tion, the compilation process hasmost probably taken considerabletime while the Senior VP is waitingfor the information. It is fair to saythat this collection and reportingprocess is more impromptu thanorganized. Every few weeks ormonths, you may have to gothrough a similar exercise, someroutine, others requested.

What is missing in the above sce-nario is a clear and concise methodof objectively, qualitatively andquantitatively reporting IFE in-ser-vice performance. Such a reportingmethod would provide the mostrealistic summary of system per-formance throughout the flight.

This article puts forward proposalsto achieve this objective fromEmirates Airline’s perspective.Some alternatives are presented.The proposals apply equally toboth wide body aircraft and singleaisle aircraft equipped with IFE.

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Performancemonitoring

of IFE systemsProposals for the future fromEmirates Airline perspective

Based on these parameters, theDMU performs several tasks, theresults of which are either found onDAR (Direct Access Recorder)cassettes, floppy disks (via MDDU- Multi Disk Drive Unit), on theMCDU (Multipurpose Control andDisplay Unit) screen or (if they aredownloaded via ACARS - AircraftCommunication Addressing andReporting System) directly on theground support computer at theairline ground station. ACMS gen-erates at least 21 reports, whichinclude several standard reportsand three user programmablereports.

PROPOSAL ‘A’ CONSISTS OF THEFOLLOWING ELEMENTS

Connect the IFE main servers suchas CMEU (Centralized Memory andExpansion Unit) and main process-ing LRUs (Line Replaceable Units)such as EPESC (EnhancedPassenger Entertainment SystemController) via ARINC 429 bus tothe DMU. There shall be at least onebus from CMEU 1 to the DMU, a

second bus from CMEU2 to theDMU and a third bus from theEPESC to the DMU.

The IFE servers shall regularlytransmit various data such as seatoperational mode (audio, video,interactive modes), seatbox healthstatus, EADB (Enhanced AreaDistribution Box) health status,handset operational status, over-head health status, AVOD (AudioVideo On Demand) availabilitystatus, CMEU availability status,AVOD storage device health sta-tus, AVOD server health status,CMT (Cabin ManagementTerminal) health status, CTU(Central Telecommunication Unit)health status, SATCOM (SatelliteCommunication Unit) availabilitystatus, seat reset status at leastonce every 30 minutes (thisshould be customizable to an air-line’s specific needs) via ARINC429 buses to the DMU. In addi-tion, software configuration dataand database configuration aresent once at the beginning of theflight to the DMU.


Proposal ‘A’ Link between IFEand ACMS

With the integration of modern,state-of-the-art technology such asfly-by-wire or Full AuthorityDigital Engine Control (FADEC),the complexity of aircraft systemshas led to the development of theAircraft Condition MonitoringSystem (ACMS). The ACMS mon-itors the data supplied by variousaircraft systems for trend monitor-ing to get maintenance relevantdata. This data enables the airlineto customize their maintenanceplanning. Long-term trend moni-toring of the engines and APU(Auxiliary Power Unit) prevents

expensive, unscheduled mainte-nance actions outside the mainbase of the airline. In addition, theACMS is presently used for vari-ous tasks such as hard landingdetection, team proficiency moni-toring and trouble shooting at thesystem level. The main objective ofACMS is more preventative innature.

The ACMS is organized around aDMU (Data Management Unit, onA340-500 the FDIMU - FlightData Interface and ManagementUnit), which interfaces with otheraircraft systems. Approximately13,000 parameters from 48 com-puters (via ARINC 429 data buses)on the aircraft are fed into theDMU.

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ACMS - Data management function for proposal A

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Proposal ‘B’Built-in conditionmonitoring

Instead of connecting the DMU via ARINC 429 data buses to coreIFE servers and processing units,this proposal necessitates fully certified software running as partof the CMEU servers 1 and 2. The core certified software isessentially ACMS report <23> IFEStability/Performance report re-hosted on CMEUs 1 and 2.

The algorithm and implementationis certified as part of the core soft-ware by the OEM (Airbus orBoeing as applicable) during thecertification process. Once certi-fied, the IFE vendor cannot modify these core algorithms. For further discussions, we shallcall this software IRM (IFE ReportDomain).

The IFE servers regularly transmitvarious data such as seat opera-tional mode (audio, video, interac-tive modes), seatbox health status,EADB health status, handset oper-ational status, overhead health sta-tus, AVOD availability status,

CMEU availability status, AVODstorage device health status,AVOD server health status, CMThealth status, CTU health status,SATCOM availability status andseat reset status at least once every30 minutes (this should be cus-tomizable to an airline’s specificneeds) via internal buses to theIRM. In addition, software config-uration data and database configu-ration are sent once at the begin-ning of the flight to the IRM.

The IRM processes all engineeringdata received from the IFE systemand generates the IFEStability/Performance report onground, at takeoff and every hourafter take off, at TOC, at TOD, attouch down and upon arrival at thegate. These reports are sent as IFEStability report <23> either to theprinter in flight, to floppy disks onMDDU or down linked automati-cally via ACARS, Data-3, swift 64or BGAN whichever is availableand selected as the channel of com-munication by the airline. A sampleof such an IFE Stability report <23>is shown previous page.

In addition to standard reporttriggers for report <23>, meansshall be provided to support user

The DMU processes all engineer-ing data received from the IFE sys-tem and generates IFE perfor-mance/stability reports on ground,at takeoff and every hour after takeoff, at TOC (Top Of Climb), atTOD (Top Of Descent), at touchdown and upon arrival at the gate.

These reports are sent as IFEStability Report <23> either to theprinter on arrival, to floppy disks onMDDU or down linked automatical-ly via ACARS, Data-3, swift 64 orBGAN (broad band), whichever isavailable and selected as the channelof communication by the airline. Asample of such an IFE Stabilityreport <23> is shown below.

In addition to standard report trig-gers for report <23>, means shallbe provided to support user defin-able triggers via the IFE database.These user definable triggers areused to monitor specific eventssuch as AVOD stream failure,CMEU server failure, and CMTfailure to capture the overallcabin IFE health conditions viareports.

In addition, the logic for thereport <23> shall provide means tocapture all commanded and com-manded seat reset data along withpertinent UTC (Universal TimeClock), data and seat location parameters.


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Seat availability explanation

Audio Video AVOD Games Interactive Telephone Airshow Camera

1 means available, 0 means not available

11 1 1 11 1 1

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For example, the seat 10B may have astatus of FC, which translates into binaryvalues 11111100 and gives the followingIFE availability:

• Audio available• Video available• AVOD available• Games available• Interactive available• Telephone available• Airshow NOT available• Camera NOT available

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The status of each seat in the IFE stability report <23> is representedby two hexadecimal digits.

definable triggers via the IFEdatabase. These user definabletriggers are used to monitor spe-cific events such as AVOD streamfailure, CMEU server failure, andCMT failure to capture the overallcabin IFE health conditions viareports.

The logic for the report <23> shallalso provide means to capture allcommanded and uncommandedseat reset data along with pertinentUTC, data and seat location parameters.

If critical changes have to beinstalled in the IRM domain, theyshall not be down linked by normaldown load procedures used by IFEsystems. Instead, these changesshall be approved by OEMs priorto controlled installation on theCMEU servers.

Softwareconsiderations inairborne systems

Presently, ACMS software is clas-sified as Level D or Level E. LevelD is assigned to report generationsoftware and Level E for the datacollection software. Report genera-tion software refers to standardreports such as the engine cruisereport and cruise performancereport, which highly influenceengine performance warranty cal-culations and scheduled mainte-nance. The IFE Stability report,which is a user definable report, is classified under Level E. All IFE software products onboard arecurrently classified as Level E systems based on DO-178B classifications.


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Comparison of the two proposalsPROPOSAL ‘A’ MERITS

Once certified, the ACMS softwarearchitecture and its implementationtend to be more stable. It has theadded advantage of rigorous controlby OEMs. The links to all otherperipherals (such a printer, MDDU,ACARS and MCDUs) are alreadyestablished and implemented as partof the ACMS system configuration.

PROPOSAL ‘B’ MERITS

No additional wiring between theIFE and DMU is necessary.Implementation is under the con-trol of one vendor without involv-ing the ACMS supplier. Integrationand testing are entirely between theIFE vendor and OEM.

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Although a sample report is provided inthis article, it could be further enhancedwith additional parameters and formattingas deemed necessary. The interval for thereport trigger and parameters to monitorcan be further refined.

There are recent developments in theindustry to implement health-monitoringsystems, which are aimed at remotelycollecting and monitoring aircraft data todetermine the status of an aircraft'scurrent and future serviceability. There ispotential to connect the IFE health

monitoring enhancements proposedabove to such systems to provide valueadded IFE maintainability services both toan airline's maintenance control centreand line maintenance teams

With the enormous complexity of presentday IFE systems, it is critical for airlines tohave a complete, comprehensive,objective window into the performance ofIFE throughout the flight, at take off and atlanding. These added tools will providethe necessary mechanism to report withconfidence the performance of IFE.

Conclusion

Mahmood AMEEN

Mahmood Ameen is currently head of the Cabin, IFE and AvionicsEngineering projects section atEmirates Airline where he serves asVice President of EngineeringProjects. In his role, he oversees thedevelopment of new IFE and Cabinsystems for all of Emirates new fleetof aircraft. He is also responsible forthe in-house retrofit andmaintenance of cabin and IFEsystems in Emirates current fleet.Mr. Ameen holds a Bachelor of Science in Aeronautical Engineeringfrom St Louis University, Missouri,USA and Master of Science in Air Transport Management fromCranfield University, UK.

Vijay RATHNAM

Vijay Rathnam is currently ProjectsEngineer in Emirates Engineering,Dubai. He serves as a focal engineerfor IFE development for Emiratesnew fleet and also is responsible forthe development of enhanced cabinlighting (mood lighting/star lighting)systems. Vijay, a US citizen, hasextensive experience in IFE industryand avionics systems (FMS, ACMS)development. He holds a Bachelor ofEngineering (Electrical) from theUniversity of Madras, and Master ofScience in Computer Science fromthe University of Texas, USA.

CONTACT DETAILS

Mahmood AmeenVice PresidentEmirates Engineering ProjectsEmirates, Dubai, UAETel: + 97 14-2181415Fax: + 97 [email protected]

Vijay RathnamProjects Engineer, IFE programsEmirates Engineering ProjectsEmirates, Dubai, UAETel: + 97 14-2181000Fax: + 97 [email protected]

About the authors...

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Illustrations provided by Emirates Airline

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This approach is global for all systemsinstalled on Airbus aircraft and includesIFE (In Flight Entertainment) systems. Both proposals in the previous articlefrom Emirates Airline are very valid ones,which in their principle complementinvestigation paths under study in

Airbus. In the next issue of FASTMagazine, we will share in more detailAirbus vision for the future for IFESystems trend monitoring and enhancedmaintenance processes using theaircraft as a major node of a network asshown above.

CONTACT DETAILS

Marc VirilliHead of Cabin and Cargo SystemsAirbus Customer ServicesTel: +33 (0)5 61 93 46 41Fax: +33 (0)5 61 93 44 [email protected]

Conclusion

PERFORMANCE MONITORING OF IFE SYSTEMS - AIRBUS VISION FOR THE FUTURE

Performance monitoringof IFE systems

Airbus vision for the future

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THE A380 MAINTENANCE PROGRAMME IS BORN! - A MAJOR SUCCESS BY ALL INVOLVED

Christian DelmasDirector Maintainability

and Maintenance EngineeringAirbus Customer Services

The A380maintenanceprogramme is born!A major success by all involved

On 23 December 2005, Airbus received accep-tance of the A380 Maintenance Review BoardReport (MRBR) from the European AviationSafety Agency (EASA). This significant achieve-ment is one major step in the A380 scheduledmaintenance activity, but not the first, nor the last.

This article describes the way this milestone wasachieved thanks to the very active and dedicatedinvolvement of hundreds of people from opera-tors, authorities, suppliers and Airbus in the MRBprocess.

Régis BrouteeDirector Maintenance Planning & ServicesAirbus Customer Services

Aircraft Health Monitoring and Management hasbeen a constant major subject for Airbus for someyears now and solutions for both raw OMS(Onboard Maintenance System) data acquisitionsuch as BITE (Build In Test Equipment) andACMS (Aircraft Condition Monitoring System)plus on-ground processing (AIRMAN*) have beendeveloped and are available on all the Airbus cur-rent product line. Enhancements of these systemsare implemented at the opportunity of each newaircraft as well as new services aimed at improv-ing pro-active and predictive maintenance basedon performance monitoring and other state-of-the-art technologies.

* AIRMAN (Aircraft Maintenance Analysis) is a real-time health monitoring andtroubleshooting solution developed by Airbus.AIRMAN constantly analyses the statusmessages sent by aircraft systems and helpsairlines to optimize their maintenance andtroubleshoot their aircraft to:• Better anticipate possible aircraft technical

events.• Improve their aircraft dispatch reliability.• Cut their maintenance and operational costs.• Improve their maintenance task efficiency.

Marc Virilli


Lufthansa Technik was nominatedISC chair by the operators panel,Airbus co-chaired the ISC andGSAC was nominated MRB chairby the JAA.

The ISC also gave the A380 PPHpreliminary acceptance and vali-dated the overall planning defini-tion to help the first A380 operatorSingapore Airlines to get a CAASapproved Operator MaintenanceProgramme for EIS (Entry IntoService). As a consequence, theoverall MRBR planning highlight-ed the need for the first MPP sub-mission to the MRBs for approval12 months before EIS.

The ISC also defined the organi-zation in charge of the develop-ment of the MRBR, relying onnine MWGs.

To ensure an optimized contribu-tion from all ISC/MWG and MRBparticipants, the ISC also set up anintensive planning for trainingsessions.

FEBRUARY TO JULY 2003:THE TRAINING SESSIONS AND A380 PPH APPROVAL

From February to July 2003,Airbus Maintenance Engineeringorganized five one-week trainingsessions around the world with thesupport of hosting customers,Airbus Engineering and A380Programme organizations. All inall, more than 350 people fromcustomers, airworthiness authori-ties, vendors and suppliers weregiven a general familiarization ofthe A380 design and trained onthe A380 PPH.

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The A380 MRBR

APPLICATION FOR THEMAINTENANCE REVIEW BOARDPROCESS

In December 2000, Airbus official-ly launched the A380 maintenanceprogramme. To meet certificationtargets, Airbus must comply withthe JAR/FAR 25-1529 Instructionsfor Continued Airworthinessapplicable at that time. As theA380 Type Certification (TC)holder, Airbus must prepare, reviseas necessary and submit forapproval to the relevant airworthi-ness authorities the initial mini-mum scheduled maintenance/inspection requirements that areapplicable to the A380 aircraft.

Just after the A380 first metal cut(Jan 2002), Airbus officiallyapplied for the MaintenanceReview Board (MRB) process tothe Joint Airworthiness Authorities(JAA) in June 2002. At this timeAirbus initiated an MRB processcompliant with:• JAA OPS Administrative &

Guidance Material Section 2-Part 2 – Chapter 16

• FAR 121 AC 121-22A

At the time of application, theapplicable Maintenance SteeringGroup method was MSG3 Rev2002.1. This is the revision that wasused to develop the A380 MRBR.

THE A380 POLICY AND PROCEDURES HANDBOOK

From June to November 2002Airbus Maintenance Engineeringdeveloped the A380 Policy andProcedures Handbook (PPH)which, compared to the MSG3document, provides additionalprocedures, details, guidance,interpretation of the rules, mainte-nance interval selection, formsheets, etc. necessary for analysis.The PPH also provides detailedwork steps, responsibilities andscheduling. Between November2002 and January 2003, Airbus

Maintenance Engineering orga-nized three working sessions withthe airworthiness authorities tofinalize the preparation of the PPHbefore submission to the IndustrySteering Committee.

The European JAA represented bythe GSAC (France), the LBA(Germany), the CAA (UK) andalso the FAA (USA) and the CASA(AUS) contributed to the A380PPH preparation.

FEBRUARY 2003:THE FIRST INDUSTRY STEERINGCOMMITTEE

From 18 to 20 February 2003,Airbus organized the first A380Industry Steering Commitee (ISC),whose responsibilities were:• To approve the A380 PPH.• To monitor the development

of the A380 MRBR and the different Maintenance WorkingGroups (MWG) activities.

• To submit the A380Maintenance ProgrammeProposal to the MRBs forapproval.

First ISC meeting participants

For more details on the MRB process

and ISC organizationsee the article in

FAST31 December 2002.

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Airbus maintenance training sessions

Industry Steering Committee schedule

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This was not achieved by chance.First of all, the active involvementof Airbus maintenance engineers inthe very early stages of the aircraftdesign development was essential.The A380 maintenance tasks inter-val targets had been selected at thebeginning of the ‘A3XX’ story,well before it became the A380. Allthrough the concept and designphases of the A380 programme,Airbus maintenance and designengineers worked together to opti-mize scheduled and unscheduledmaintenance. Their target was tooffer an A380 with optimizedmaintenance costs to operators,while maintaining safety as the pri-mary objective. All design specifi-cations are defined so that theA380 design fulfils the initialMRBR targets and also remainscompatible with future mainte-nance programme evolutionsaccording to in-service experience.

All through the A380 design devel-opment and the MRB process,operators, airworthiness authoritiesand Airbus challenged each other,contributing to the continuousimprovement of the overall MRBprocess with the common objectiveto offer the A380 with the mostappropriate maintenance pro-gramme to support a safe, reliableand economical aircraft operation.This led to the development of verythorough MSG3 analyses and theselection of the most appropriatetasks and intervals.

Consequences of the A380 MRBR proposalacceptance versusthe MRBR approval

Readers familiar with the MRBProcess may wonder why ‘MRBRProposal’ acceptance is mentionedinstead of ‘MRBR approval’ in thisarticle.

According to the Instructions forContinued Airworthiness (ICA)JAR/FAR 25-1529, an approvedMRBR is required at the latest foraircraft EIS. However, as agreed bythe ISC the A380 MRBR planninghas been developed in such a waythat enough time is provided to thefirst operator to get approval for itsOperator Maintenance Programme(OMP) by its local authorities.

Consequently, review of the MSG3analyses started in July 2003 basedon the design known at that time.Because of this and the numerousdesign changes that typically hap-pen during the design and flighttest phases, the MRBs were not ina position to approve a documentcovering the aircraft EIS designstandard at this time.

In addition, during the develop-ment and review of the MSG3analyses by the MWGs, some

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JUNE 2003:THE PPH APPROVAL

In the mean time, thanks to thelessons learned during the trainingsessions, the PPH was updated andgot its first approval by the ISC andacceptance by the MRBs in June2003. The major highlights of thisPPH are the aircraft yearly utiliza-tion for medium/long haul routes.

The A380 PPH becomes theindustry benchmark in the opin-ion of the MRBs and operatorswho report it as the best they haveever seen.

The MWG activityFrom June 2003 to March 2005, thenine MWGs reviewed the MSG3analyses for A380 systems, struc-tures and zones selecting the mostappropriate scheduled maintenancetasks to ensure a safe, reliable andeconomical aircraft operation.

During this 21 month period, morethan 900 MSG3 dossiers preparedby Airbus and major vendors main-tenance engineers, representing theequivalent of more than 30,000MSG3 analysis pages (equivalent)were reviewed during 54 MWGmeetings from which close to1,000 scheduled maintenance taskswere selected.

The first A380MaintenanceProgrammeProposal (MPP)Thanks to the efficient MSG3analyses production and qualitymonitoring process controlled bythe ISC, the initial target was met:The A380 MPP is ready for reviewand acceptance by the A380 ISCin March 2005.

During the tenth meeting in March2005 the ISC completed review ofthe MWG results and concluded thatthe selected scheduled maintenancetasks and associated intervals are themost appropriate ones. The ISC thenaccepted the compiled MPP.

On 8 April 2005, some days prior tothe A380 maiden flight, the firstA380 MPP was submitted to theMRBs for acceptance according tothe planning set up more than twoyears earlier. Early involvement indesign phases and very active opera-tor involvement were two key issues.

Most of the initial technical objec-tives were met in the A380 MRBRproposal, particularly the objec-tives associated with task selectionand interval definition.

During Maintenance Working Groups activities

Task completion progress

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• In-service experience(AD/CN, Service Bulletins (SB), Service Information Letters (SIL), All Operators Telex (AOT)…)

The MPD provides additionalinformation for each sched-uled maintenance task suchas, access, zones, source data,preparation work, man hours,elapsed time and reference tothe associated AircraftMaintenance Manual (AMM)procedure.

Similar requirements for dif-ferent sources are consolidat-ed in the MPD at task and/orThreshold/ Interval level.

At this stage of the A380 pro-gramme, the MPD containsonly data coming from theMRBR proposal.

A SIMPLIFIED MPD WITH NEW FEATURES

Compared to other Airbus pro-grammes, the A380 MPD is sim-plified. Volume 2 is deleted as:• The zoning and access

illustrations previously coveredin section 10 and 11 areredundant with AMM Chapter06 information.

• The illustrations of the StructureSignificant Items (SSI) from theMRBR structures section,previously covered in section 12are now available in the relevantAMM procedures.

With experience gained from otherAirbus programmes and in agree-ment with the A380 ISC, a newtask numbering concept was intro-duced to be self-explanatory andremain compatible with futuremaintenance programme and plan-ning evolution. To assist operatorsmaintenance planning organiza-tions, a new appendix for mainte-nance planning is available. In this, all MPD tasks whatever the source,are packaged into maintenancechecks according to typical aircraftoperations.

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THE A380 MAINTENANCE PROGRAMME IS BORN! - A MAJOR SUCCESS BY ALL INVOLVEDTHE A380 MAINTENANCE PROGRAMME IS BORN! - A MAJOR SUCCESS BY ALL INVOLVEDFA

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assumptions on Flight Manual(FM) and Master MinimumEquipment List (MMEL) aremade. These assumptions must becleared for the MRBR approval. Toprotect the first A380 operator’sinterests an agreement is thereforefound between operators, MRBsand Airbus:• The first MRBR will be called

‘MRBR proposal’ and will notbe approved but accepted by theEASA. It will thus berecognized as an acceptablebasis by the first operators localairworthiness authority forapproval of the first OMP.

• All design changes will beanalysed by Airbus maintenanceengineering for MSG3 analysesupdate and review by therelevant MWG prior tosubmission of the MPP to the MRBR for approval. This process is a standard onethat remains applicablethroughout the aircraft life inthe MRBR revision process.

• All assumptions taken andrecorded during review of theMSG3 analyses must beconfirmed, if not, MSG3analyses and MRBR must bereviewed and updatedaccordingly.

• The ‘MRBR Proposal’ will be updated according to thechanges identified during theMarch 2005 - June 2006 MWGand ISC meetings andsubmitted to the MRBs to be approved prior to EIS. This will become the firstA380 approved MRBR.

• The first A380 operator, at thattime, will only have to integratethe changes in its OMP in orderto get approval from its localairworthiness authority.

This agreement offers benefits:• To the first A380 operator who

can anticipate their programmeand planning to minimize workload just prior to EIS andlimit it to a programme revision.

• To all A380 operators whocan prepare in advance theirmaintenance programme andplanning.

• To local authorities who havecontributed to the MRB processand can approve their operatorsOMP more quickly.

The A380MaintenancePlanningDocumentA SCHEDULED MAINTENANCE DATA REPOSITORY

Parallel to the A380 MRB process,Airbus Maintenance Planningorganization prepared the A380Maintenance Planning Document(MPD) with new and enhancedfeatures. The MPD is a single ref-erence for all repetitive tasks recommended by Airbus and is anon-approved document that con-tains approved and non approvedscheduled maintenance require-ments from:• The MRBR• The Airworthiness

Limitation Items document(ALI)

• The Certification Maintenance Requirements document (CMR)

New task numbering concept

New appendix for maintenance planning

Maintenance Planning Document on CD

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A marvellous experience and a real teamspirit. The acceptance of the A380 MRBRproposal by EASA is a major step in theA380 maintenance programmedevelopment. This was achieved thanks toa very efficient ISC organization whereoperators, airworthiness authorities, majorsuppliers and Airbus joined efforts to givethe A380 a maintenance programme atthe same level as the aircraft: A referencein the industry.

Hundreds of thousands of working hourshave been invested in the A380 MRBR,more than 8,000 meeting man-days, morethan 30,000 equivalent pages ofdocuments prepared, reviewed andvalidated by hundreds of people. All thiswas performed in a very professional andvery friendly atmosphere.

The result is that the A380 has amaintenance programme ready forimplementation. The MPD provides thetools to help operators develop theirmaintenance programme (OMP) get itapproved by their local airworthinessauthority and prepare the associated A380maintenance schedule. AirbusMaintenance Planning Organization offerscustomized services to help operators inthese activities.

The A380 has not yet been delivered to itsfirst customer but the MRBR and the MPDhave already switched from thedevelopment to the revision phase.

Airbus Maintenance Planning organizationhas developed a specific assistance forthe Flight Test department. The A380 flighttest aircraft scheduled maintenance isalready performed according to the A380MPD, customized to the aircraft definitionand operation.

A very efficient resultFirst technical evaluations of the A380maintenance programme, based onstandard aircraft operation confirms thatthe initial MRBR targets are met:• An equivalent A check can be scheduled

every 750fh• An equivalent C check can be

scheduled every 24 months/6,000fh• Structure inspections can be scheduled

every 6 and 12 years

This leads to significant maintenanceman-hours and maintenance cost savingscompared to aircraft with similaroperations.

Conclusion

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AirN@v module ‘AirN@v / Planning’


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A SIMPLIFIED MPD AVAILABLE IN MULTIPLE FORMATS

The A380 MPD and associatedfeatures are available in multipleformats to meet operators expecta-tions and provide an easy interfacewith their systems.

In particular, the AirN@v module‘AirN@v / Planning’ offers thepossibility to be 100% compatiblewith the other AirN@v new gener-ation of technical data browsingtools, which are easy to use andinteractive (see article in FAST 35).

Next steps

As previously mentioned the A380MRBR Proposal acceptance byEASA is the first major step in thedevelopment of the A380 sched-uled maintenance documentation.It was not the first one, and it willnot be the last.

THE MRB PROCESS

Following ISC, MRBs and Airbusagreement, the A380 MRBR willbe updated according to designchanges to obtain a formal approvalfor EIS of the first aircraft. Then,once the A380 becomes an in ser-vice aircraft, the MRBR will fol-low a standard revision processaccording to:• Design changes• New regulations• In-service experience feedback

For this, it is essential that from dayone, A380 operators collect inappropriate databases the results ofthe scheduled maintenance tasks(findings and nil findings) to latersupport MRBR evolution exercises.

THE AIRWORTHINESSLIMITATION ITEM

The Airworthness Limitation Item(ALI) process has also started withthe target to get the A380 ALI document approved for the A380type certification (compliance toJAR/FAR 25-571).

A380 fatigue and damage toler-ance evaluations will be performedand associated scheduled mainte-nance requirements will be pub-lished in the A380 document attype certification. The ALI willlater be updated once results fromthe fatigue test cell are available.

THE CERTIFICATION MAINTENANCEREQUIREMENT

The process has also started. TwoCertification Maintenance Coordi-nation Committee meetings havetaken place with operators and air-

worthiness authorities to performthe MSG3/SSA (System SafetyAssessment) compatibility checkthat leads to selection of theCertification Maintenance Requi-rement (CMR) (compliance withJAR/FAR 25-1309). As with theMRBR development process, earlyinvolvement of Airbus maintenanceengineers during the design phasesis essential to reduce the number ofCMRs to the minimum.

THE MPD

The A380 MPD will be revisedevery time one of the source docu-ments is revised. To minimize theburden on operator’s maintenanceplanning organizations, MPD revi-

sions will combine source docu-ment revisions as much as possibleaccording to the different planningand document approvals.


CONTACT DETAILS

Christian DelmasDirector Maintainability and Maintenance EngineeringAirbus Customer ServicesTel: +33 (0)5 61 93 14 04Fax: +33 (0)5 61 93 28 [email protected]

Régis BrouteeDirector MaintenancePlanning & ServicesAirbus Customer ServicesTel: +33 (0)5 67 19 02 13Fax: +33 (0)5 61 93 22 [email protected]

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HYPOXIA - AN INVISIBLE ENEMY - CABIN DEPRESSURIZATION EFFECTS ON HUMAN PHYSIOLOGY

Operating at high altitude withoutadequate understanding, trainingor equipment protection can bedangerous as shown by the follow-ing extracts from two accidentreports:

‘One of the first encounters withthe dangers of high altitude flightwas reported in 1862 when a bal-loon flight was made to study theeffects of low ambient pressure.The balloon ascended to approxi-mately 29,000ft and during theflight a series of “strange” symp-toms, notably loss of visual andhearing capability, paralysis ofarms and legs, and finally, uncon-sciousness occurred. The teamcould have been lost, but wassaved by one member pulling theballoon valve rope with his teeth(his arms were already paral-ysed), to descend the balloon. Theteam recovered as the balloondescended, but this marked for thefirst time the risk of low ambientpressure.’

‘In 1998 a decompression incidentoccurred on an aircraft at35,000ft. Both the captain and thefirst officer had received altitude-chamber training during their pre-vious military careers and knewabout the effects of low cabinpressure. The first officer attempt-ed to control the cabin rate ofclimb by switching to the standbypressurization system. When useof the standby system failed toimprove the situation, he donnedhis oxygen mask. The captain, whohad been talking with a passengerwho was visiting the flight deck,attempted to don his oxygen masktoo, but in doing so he knocked hisglasses to the floor. When trying toretrieve them he lost conscious-ness and slumped forward. Thefirst officer attempted to help thecaptain but was unable to do this,so initiated a descent to 25,000ft.A short time later the first officerasked the senior flight attendantto assist the captain. To enter theflight deck the flight attendant hadto remove her oxygen mask con-nected to the fixed cabin oxygen

system. She decided not to use theportable oxygen equipment andwent straight to the flight deck.Before being able to assist thecaptain she collapsed onto thefloor. Once again, the first officerattempted to put on the oxygenmask for the captain, this timesuccessfully. Soon afterward, thecaptain regained consciousnessand was unaware he had beenunconscious, which is a typicalreaction from a victim of hypoxia.’

The hypoxiaeffects of a quick cabindepressurization

During a quick depressurizationthe partial pressure of oxygen inthe lungs/alveolae reduces rapidlywith the effect of reverse diffusion.This means that once the oxygenpartial pressure in the alveolae hasreached a level that is below thelevel in the blood, the blood oxy-gen moves out of the body backinto the ambient air. This effect ofreverse diffusion unfortunately fur-ther reduces the already very limit-ed oxygen storing capability ofblood and supports hypoxia effects.Holding of breath cannot stop thereverse flow since the pulmonarygas expansion would lead to seri-ous lung injury.

Severe hypoxia caused by a signif-icant reduction in cabin pressure isvery dangerous for flight crewbecause:• The victims of hypoxia rarely

notice that they are about topass out.

• Usually there is quickly a lossof critical judgment

• Most victims often experience amildly euphoric state

• Thinking is slowed, muscularcoordination is impaired

The only effective means of protection is the quick donning ofoxygen masks as the first action -before troubleshooting!

Human physiology

Within the lungs the alveola provide the interface betweenair and blood. The blood which is returned from the bodytissue into the alveolae has given away most of its oxygenso that the oxygen partial pressure in the lungs is higherthan in the arriving blood. A process of diffusion thendrives oxygen through the thin alveolar wall into the blood.

The most important parameters for the oxygen diffusionprocess are the oxygen percentage and barometricambient pressure. Changing these parameters changesimmediately the oxygen saturation level in blood and withit the oxygen supply to the body tissue. Unfortunately,there is no significant storage of oxygen in the humanbody, unlike many other chemical substances necessaryto maintain life. The blood is the only storehouse foroxygen, and its capacity is very limited. Hence, thehuman body lives only a hand-to-mouth existence withits oxygen supply.

As the pressure of air in the atmosphere decreases withincreasing altitude, the partial pressure of oxygen in theair reduces and with it the diffusion of oxygen into thebody. Reduction of oxygen availability in the body resultsin loss of functions ranging from slight impairment up todeath. It is the nervous system, in particular in the highercentres of the brain, and the eyes which have a highmetabolism with no oxygen reserve. These are mostsensitive to oxygen depletion and therefore are the firstto be affected by a reduced oxygen supply.

For healthy persons altitude exposure up to 15,000ft isusually not hazardous since cardiovascular andrespiratory compensatory mechanisms (faster breathingand increased pulse rate/blood circulation) act tomaintain adequate oxygenation at the cellular level.

The effects of reduced oxygen supply to the body(hypoxia) vary between persons, depending on health,physical fitness, age, activity level and statistical scatterwith the population. Pilots and flight attendants usuallyrequire more oxygen during an emergency than healthy,seated passengers and might therefore suffer earlierfrom hypoxia effects.

HYPOXIA - AN INVISIBLE ENEMY - CABIN DEPRESSURIZATION EFFECTS ON HUMAN PHYSIOLOGYFA

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Hartwig AsshauerCertification Manager

Hydro-Mechanical & Air SystemsAirbus Engineering

When public air transportation first becamecommonly available, flights did not reach alti-tudes that represented a significant risk ofreduced oxygen supply - called hypoxia - toeither passengers or crew. However, in the late1940s and 1950s aircraft were developed thatallowed safe transport of the flying public at altitudes around 40,000ft, which have remainedrelatively constant since then.

DEFINITIONS OF HYPOXIA

Hypoxia is separated into four types:• Hypoxic hypoxia is a condition caused by reduced

barometric pressure, affecting the body's ability totransfer oxygen from the lungs to thebloodstream.

• Histotoxic hypoxia can be induced by theintroduction of substances like alcohol or drugsinto tissue, reducing its ability to accept oxygenfrom the bloodstream.

• Hypaemic hypoxia (or anaemic hypoxia) is a resultof the blood being unable to carry oxygen, e.g.caused by exposure to carbon monoxide.

• Stagnant hypoxia results from the body's inability to carry oxygen to the brain, which canresult from high gravity-forces causing blood topool in the lower extremities of the body.

Hypoxia An invisible enemy

Cabin depressurization effectson human physiology

GENERAL BLOOD CIRCULATION

Oxygen partial pressure

The concentration of oxygen in theatmosphere is constant at 20.95%at altitudes up to 100,000ft, whichmeans that according to Dalton'sLaw* the oxygen partial pressureat sea level is 212mbar (20.95% of1013mbar where 1013mbar is thestandard atmospheric pressure atsea level).

As altitude increases above sealevel the partial pressure of thecomponent gases decreases consis-tent with the decrease in totalatmospheric pressure. For exam-ple, the partial pressure of oxygenat 40,000ft is reduced to 39mbaronly, which is far too inadequate tosupport human metabolism.

One means to increase oxygen par-tial pressure is to increase the oxy-gen concentration in breathing air.At 40,000ft cabin altitude an oxy-gen partial pressure of maximum188mbar can be achieved bybreathing pure oxygen (100% oxy-gen concentration without over-pressure).

Another additional means forhypoxia protection is positivepressure breathing, which is usu-ally found in modern crew oxy-gen masks and means the deliveryof pure oxygen under pressureinto the respiratory tract. For civilapplications positive pressurebreathing is able to increase addi-tionally the oxygen partial pres-sure by around 20 to 30mbar provided that the overpressurecondition is limited to some min-utes only. This means that at40,000ft it requires 100% oxygenconcentration of the breathing gascombined with positive pressurebreathing to achieve sea levelequivalent conditions. Positivepressure breathing requires sometraining and is tiring and inconve-nient, which is the rationale forhaving so far provided this pro-tection feature to flight crew only(for short time use only).


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* Dalton’s Law(1766 -1844)In 1801, the English astronomerand chemist, John Dalton,discovered the pressurerelationship among gases in amixture. Dalton's Law states thatthe pressure exerted by a mixtureof gases is equal to the sum ofthe pressures that each wouldexert if it alone occupied thespace filled by the mixture.

Current oxygen mask for passengersê

ç Early type of shaped oxygen mask for passengers

ç

Time of UsefulConsciousness

In the 'World of Hypoxia' the Timeof Useful Consciousness (TUC) isa very important parameter. Forlow ambient pressure conditions itindicates the time available to per-form purposeful activities, such asoxygen mask donning or aircraftcontrol. Beyond this time framemental and physical capabilitiesare dangerously impaired andfinally result in unconsciousnessand potentially death.

As shown in the table on the right,TUC is negatively correlated withaltitude. It is important to note thateven if activities are performedwithin the TUC time frame there isa significant deterioration of workrate and mental capability, which iscorrelated with the time spent at lowpressure conditions (at the end ofthe TUC time frame, performance ismuch lower than at the beginning).

The TUC is the 'Window ofOpportunity' for donning an oxy-gen mask and can be very limitedso must take overriding precedenceover any other activities.

Time of SafeUnconsciousnessSome experts believe that for pas-sengers - in contradiction to theflight crew - a short period ofunconsciousness during cabindepressurization can be toleratedsince they are not performing anoperational task. Unconsciousnessis a clear sign of insufficient oxy-gen supply to the brain and it isobvious that this time can only bevery short before permanent braindamage occurs. So far, it has notbeen possible to associate a specif-ic time frame for the safe time ofunconsciousness.

The uncertainties in extrapolationof animal data and the wide vari-ability in individual toleranceshave so far prevented determina-tion of a commonly agreed valuefor Time of Safe Unconsciousness(TSU) among human physiologyexperts. It is believed that a safetime of unconsciousness is some-where between 90 seconds and 4 minutes.

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20,000ft All unacclimatized personslose useful consciousnesswithin 10 minutes

25,000ft Useful consciousness is lost after 2.5 minutes or less

30,000ft TUC: approx. 30 seconds

37,000ft TUC: approx. 18 seconds

45,000ft TUC: approx.15 seconds

ê Mask straps inflated

These data on TUC are averaged values based on tests with healthyindividuals when breathing ambient air (no supplemental oxygen provided).A large individual variation in the effects ofhypoxia has been found. There is evidencethat TUC is shorter for people exposed tostress conditions.

Time of Useful Consciousness

ê Mask in place

è

* Manufacturer EROS

Flight crew oxygen mask *

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The first step for any flight crew memberfaced with cabin depressurization shouldbe the immediate donning of an oxygenmask. Any delay in donning a mask willsignificantly increase the risk of losingconsciousness before cabin pressure isregained. Severe hypoxia leads usually tothe loss of critical judgement combinedwith a mildly euphoric state, which makeshypoxia very dangerous for flight crew.This is highlighted also in the FAA SpecialCertification Review that was issued someyears ago on the effects of cabindepressurization.

Moreover, in case of rapid cabindepressurization a quickly accomplishedemergency descent is often the onlymeans of fast re-oxygenation of

passengers that were unable to protectthemselves against hypoxia by using thepassenger oxygen masks provided.Severe hypoxia is very dangerous forunprotected passengers and requires aquick return to an adequate cabinpressure or where not possible (abovehigh terrain), it requires a check by theflight attendants that the passengeroxygen masks are correctly used.

For a long time transport aircraft havebeen equipped with oxygen systems forflight crew and passengers that provide anadequate protection against hypoxia. Aslong as these oxygen systems are usedaccording to their simple procedures theinvisible enemy hypoxia poses littledanger to flight crews and passengers.

CONTACT DETAILS

Hartwig AsshauerCertification ManagerHydro-Mechanical & Air SystemsAirbus EngineeringTel: +33 (0)5 62 11 04 98Fax: +33 (0)5 61 93 31 [email protected]

Airworthinessrequirements

The Airworthiness authorities haveidentified the risk of hypoxia andhave created requirements (seetable on the left).Also, after an accident in the USAthe FAA initiated a SpecialCertification Review (SCR) onpressurization systems. The SCRrecommends that the aircraft flightmanual (for aircraft certified forflights above 25,000ft) require inthe emergency procedures thedonning of oxygen masks as thefirst crew action after a cabin altitude warning.

This highlights again the impor-tance of immediate donning ofoxygen masks when cabin depres-surization occurs.


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Oxygen equipmenton civil aircraftOn modern aircraft oxygen equip-ment is installed to provide ade-quate protection against the dam-aging effects of hypoxia in case ofcabin depressurization:

For flight crew there are usuallyquick donning oxygen masksinstalled, which can be donnedwith one hand in less than 5 sec-onds. The mask straps are com-bined with elastic tubes thatinflate and stiffen when the maskis taken from its stowage, allow-ing the mask to be easily put overthe head with one hand. Once thegrip on the mask is released, thetubes deflate and their elasticcharacteristics ensure a perfect fit.The required oxygen concentra-tion of the breathing air is auto-matically adapted to the cabinpressure.

For the passenger oxygen supplythe continuous flow concept isused on all Airbus aircraft.Oxygen is delivered continuouslyto an expandable oxygen bagwhere it is conserved during exha-lation, so it is available during thenext inhalation to supplement thesteady oxygen flow.

It was decided at an early stage inpassenger oxygen mask develop-ment that the untrained civilianpopulation should not be expectedto recognize the correct orienta-tion for a shaped mask, and it wasrequired that a mask should beoperable in any position in whichit might be donned by the user. A second basic requirement wasa universal size, which finallydefined the well-known cylindri-cal mask body.

Effect on human physiology of moderate cabin altitude

Very large numbers of aircrew and passengers have been exposed to breathing air at cabin altitudes up to 8,000ft over the last 60 years without significant deleterious effects. Although exposure to this altitudereduces the oxygen partial pressure in the pulmonary tract the tissues of the body are maintained wellabove the required level.

Some airlines still allow smoking in the aircraft cabin, which results in carbon monoxide inhalation withthe smoke. Carbon monoxide has a 240-times greater tendency than oxygen to attach to red bloodhaemoglobin, thus inactivating a large amount of haemoglobin as an oxygen carrier. It has been found thatthe hypoxia effects from carbon monoxide and altitude are additive; hence chronic smokers are at ahigher equivalent altitude than non-smokers in terms of blood oxygen supply.

Also, alcohol poisons body tissues in such a manner that they cannot use oxygen properly. Usually, it isnoticed by passengers that the physiological effect of alcohol consumed during flight is more intense thanat sea level, which is due to the additive hypoxia effects of alcohol and altitude.

GENERAL• CS/FAR 25.841 (a): Maximum cabin pressure altitude under normal operation: 8,000ft• CS/FAR 25.841 (a): Maximum cabin pressure altitude after any probable failure condition in the

pressurization system: 15,000ft• FAR 25.841 (a) (2) (i): Maximum exposure time to cabin pressure altitude exceeding

25,000ft: 2 minutes• FAR 25.841 (a) (2) (ii): Exposure to cabin pressure altitude that exceeds 40,000ft: Not allowed

CABIN OCCUPANTS• CS/FAR 25.1443 (c): Provides oxygen system performance data on oxygen flow and

required partial pressure of oxygen• CS/FAR 25.1447 (c) (1): The total number of masks in the cabin must exceed the number

of seats by at least 10%• CS/FAR 25.1443 (d): Defines oxygen flow for first-aid oxygen equipment (for cabin

depressurization treatment)• JAR OPS 1.760/FAR 121.333 (e) (3): Requires first-aid oxygen for at least 2% of

passengers • JAR OPS 1.770 (b) (2) (i)/FAR 121.329 (c): Defines the percentage of passengers that need

to be provided with supplemental oxygen (cabin pressure altitude dependent)

FLIGHT CREW• CS/FAR 25.1443 (a) & (b): Provides oxygen system performance data on oxygen flow and

required partial pressure of oxygen • CS/FAR 25.1447 (c) (2) (i): For aircraft operating above 25,000ft quick donning oxygen

masks are required for the flight crew which can be donned with one hand within 5seconds

• FAR 121.333 (c) (2) (i) (A): One flight crew member needs to wear permanently his oxygenmask when the aircraft is operated above FL410

• FAR 121.333 (c) (3): In case one flight crew member leaves the controls the remaining pilotneeds to use his oxygen mask when the aircraft is operated above 25,000ft

Extract of the prime requirements

Fuel QuantityIndication System The Fuel Quantity IndicationSystem (FQIS) measures the quan-tity of fuel in each of the aircraftfuel tanks. The FQIS provides thisinformation to the flight deck pro-viding a display of the Fuel onBoard (FOB) and, via the ECAM(Electronic Centralized AircraftMonitor) systems page, the indi-vidual tank quantities. On theA300/A310 and A330/A340 fleetsthe data is used in the auto-transferfunctions e.g. CG (Centre ofGravity) control.

Airbus aircraft utilize capacitanceto measure the level (volume) offuel within the aircraft fuel tanks.Vertical probes located through-out the tanks measure the fuellevel in the tanks. Each probe hastwo concentric aluminium tubes.The open ends of the tubes allowthe fuel to move freely up andbetween the tubes. The capaci-tance value of the probe changesin proportion to the depth of fuelwithin the tank. When the probe isdry the capacitance value is low,but as fuel moves up the probe thecapacitance value increases. Fueldensity is measured for exampleusing the fuel dielectric value orvariations with the speed ofsound. The FQIS uses the volumeand density values to calculate themass (kg or lb).

The effect ofmicrobiologicalcontamination onan aircraft FQISThe probes and downstream calcu-lations are calibrated for use in jetfuel. The probes measure from'unusable' to full tank capacity.However, when the fuel is contam-inated the fuel characteristicschange. The probes may alsobecome contaminated. Typically,the probes will now read a highercapacitance level than the real fuel

level. In some cases the probe willover-read or 'disagree' with aneighbouring reading.

At aircraft level on the flight decka key symptom of severe fuel contamination is FQI fluctuationduring flight, or degraded FQIindication.

In some cases aircraft dispatch may be limited by the status of theFQI display (please refer to theMMEL).

Symptoms andpreventionOperators are encouraged to focuson prevention of microbiologicalfuel contamination to avoid the penalties associated withoccurrences. The bacteria causingsuch contamination live within thewater/fuel interface and these liv-ing organisms enter either via thefuel supply or are airborne.However, to live and develop with-in the tank the bacteria requirewater (for oxygen). Therefore, thefirst consideration in prevention isminimizing water content in the

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FUEL CONTAMINATION - PREVENTION AND MAINTENANCE ACTIONS

Degraded indication on theECAM

FUEL CONTAMINATION - PREVENTION AND MAINTENANCE ACTIONSFA

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Christopher McGregorGroup Manager Fuel Systems

Airbus Customer Services

Airbus continues to focus on optimizing aircraftavailability and a key issue is the availability ofthe Aircraft Fuel Quantity Indication System(FQIS). Within the industry the major threat to theFQIS availability is microbiological contamina-tion of the fuel. Such contamination will impactthe FQIS readings, typically driving the FQISprobe readings out of limit. If left untreated, con-tamination can also generate acids in the fueltanks, which may attack the wing tank structure.

Airbus has for many years worked with our part-ners in IATA (International Air TransportAssociation) on this issue. This work culminatedin publication of the IATA Guidance Material onFuel Contamination, which summarized the sci-ence behind contamination and collated the bestrecommendations from the OEMs (OriginalEquipment Manufacturers), operators andmicrobiologists.

Airbus continues to develop recommendationsbased on operator feedback and this article sum-marizes current knowledge on prevention andmaintenance actions.

Fuel contamination

Prevention and maintenance actions

fuel tank system. All modern civilaircraft incorporate water drainageand/or scavenge systems to helpachieve this. The Airbus wingdesign ensures water is maintainedin suspension and fed to theengines; any remaining water isthen drained at regular intervalsvia the water drain valves. Thewater drainage interval for eachAirbus aircraft programme isdetailed in its MaintenancePlanning Document (MPD).

A second key element of preven-tion is monitoring. Often over-looked is the need to visuallyinspect any water resulting fromthe MPD water drain task. Drainedwater and fuel will separate withinthe container with the water settling to the bottom. Both shouldbe clear with no particulates

evident to the naked eye. Any'cloudiness' in either fluid indicatespossible contamination and actionis required.

Currently, Airbus recommends anannual analysis of fuel from eachaircraft to test for fuel/water cont-amination, which should be con-sidered a minimum for all opera-tors. However, each individualoperator needs to assess their risklevels, especially their experienceat aircraft and fuel supply leveland define their testing require-ments accordingly as an annualtest may not be sufficient in some circumstances.

There are a number of fuel contam-ination test kits available in themarket place, each with advantagesand disadvantages. The main issuewith all test kits is that they cannotbe used as a single snapshot to pro-vide a detailed analysis of tank con-ditions. However, they can be usedeffectively to create a baseline foroperation from which an increasein contamination can be observedand the appropriate action taken.

In summary, the key indicators offuel contamination are particulatesobserved in drained water, resultsfrom the fuel analysis or FQI fluc-tuations, or degradation observedon the flight deck. If no action istaken and these symptoms areignored engine main filter clogevents can be anticipated.

MaintenanceactionsIn all cases operators are recom-mended to include contaminationprevention in their maintenanceprogramme. Based on the previousexplanation the most importanttasks are water drainage and fuelmonitoring.

Another possibility is sharing the common objective of preventionwith an operators fuel supply company. Currently there are norequirements for fuel supply com-

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panies or distributors to test formicrobiological fuel contamination.

In these discussions we refer oper-ators to the JIG (Joint InspectionGroup). Under the IATA umbrellaairport facilities are audited andactions taken to maintain the qual-ity of the fuel supply.

If fuel contamination is detected, theindustry has developed the follow-ing guidance and recommendations.This flow-chart will be integratedinto all Airbus aircraft AMMs(Aircraft Maintenance Manuals). Itis difficult to provide a single rec-ommendation to cover all scenariosbut the flow-chart does summarizevery well the thought process andobjective of avoiding fuel tank entryif at all possible.

Currently within the industry twobiocides are approved for aviationuse. The maximum concentrationsare defined in the Airbus AMMsand are a compromise between theeffectiveness of the biocide and themaximum concentration allowedby the engine and APU (AuxiliaryPower Unit) manufacturers. Theseconcentrations allow treated fuel

to be burnt by the engines andavoid operators disposing of thetreated fuel.

Airbus recommends metered injec-tion of the biocides to ensure ade-quate mixing within the fuel. Thebiocides are not effective at lowtemperatures hence the soak timedefined in the AMM cannotinclude flight time.

If tank contamination is severe thebiocides will only kill the outerlayer of bacteria attached to the tankand probe surfaces. Therefore, asper the flowchart, tank entry andcleaning is recommended to removeall visible traces of contamination.The time, schedule disruption andcost of tank entry is well understoodand appreciated by Airbus. Hence,the need to focus on prevention toavoid this financial impact is cru-cial. If a decision is taken to enter atank, Airbus recommends a thor-ough cleaning of it. The pressure toreturn an aircraft to service is wellunderstood, but if a tank is not thor-oughly cleaned there is a significantrisk of contamination developingagain requiring additional futuremaintenance action.


1) Get a fuel sample2) Use a biological test kit

• Low level of bio contamination requires regular monitoring (within 1 to 12 months)

Low

Low

High or moderate

High

• Repeat the bio contamination test within 10 days

• Do the microbiological detection test again in 10 days, but after at least 5 flights. Take corrective action if necessary

• Within 10 days enter the fuel tank for inspection,

• Physically remove microbiological deposits as per AMM 28-11-00 Page Block 301• Physically remove microbiological deposits as per AMM 28-11-00 Page Block 301

• Within 10 days apply biocide to all fuel tanks as per AMM 28-11-00 Page Block 301

Level of contamination?

Level of contamination?

Microbial growthinspection and maintenanceactions


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In-tank observation ofmicrobiological fuelcontamination: fuel contamination attached tothe tank structure

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Prevention is the key to avoidingmicrobiological fuel contamination. Water drainage and fuel sample analysisare the critical tasks at aircraft level. All fuel contains a background level ofbacteria, so minimizing water contentwithin the aircraft fuel tanks will significantlyreduce the risk of contaminationdeveloping within the tanks. In the longterm, preventing contamination will reducethe future potential for structural corrosionand damage to in-tank components.Again, the key indicators of fuelcontamination are particulates observed in drained water, results from the fuel

analysis or FQI fluctuations or degradationobserved on the flight deck.

Operators are recommended to consult theIATA Guidance Material on MicrobiologicalContamination in Aircraft Fuel Tanks forassistance in planning contaminationprevention tasks. In addition please consultAirbus Service Information Letter 28-079.Success against contamination requireslong-term industrial co-operation. Withinthe IATA framework Airbus will continue towork with industry partners to combat fuelcontamination and optimize prevention andmaintenance practices.

Conclusion

CONTACT DETAILS

Christopher McGregorGroup ManagerFuel SystemsAirbus Customer ServicesTel: +33 (0)5 62 11 76 02Fax: +33 (0)5 61 93 44 [email protected]

DevelopmentsThe current recommendations onprevention and maintenance taskshave taken many years to developand Airbus recognizes the effortsand expertise of our partners inIATA. As a result, today there ismuch more advice and guidanceavailable at aircraft and fuel supplylevel than ever before.

For the future Airbus will continueto look at ways of reducing theassociated maintenance burden.

For the A320 and A330/A340 families of aircraft engineeringaction has been launched to further develop the water managementsystems within the aircraft. The objective is to enhance thewater scavenge efficiency and at alater date extend the water drainageinterval; this is a MRBR(Maintenance Review Board

Report) entry and hence changesrequire airworthiness authorityinput and approval.

For the A330/A340 Family anactivity is launched to study reduc-ing the impact of contamination onthe FQI.

Airbus also intends to study newand more effective biocides, whichare available in the market place,but not currently approved withinthe aviation industry. Biocideapproval however is a long lead-time item requiring primarilyengine manufacturer approval.There are also significant health andsafety issues to consider. Furtherinformation on this initiative will beannounced when available.

FURTHER READING

Airbus DocumentationSIL 28-079 • AMM 12-32-28 • AMM 28-11-00 • MPD 28-11-00

Key partnersECHA MICROBIOLOGY www.echamicrobiology.co.ukCONIDIABIOSCIENCE www.conidia.comMERCK www.microbiology.merck.deTANK TIGERS www.aoginc.comTANK DEVILS www.tankdevils.com

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Customer Support CentresTraining centresSpares centres / Regional warehousesResident Customer Support Managers (RCSM)

RCSM location Country

London United KingdomLouisville United States of AmericaLuton United KingdomMacau S.A.R. ChinaMadrid SpainManchester United KingdomManila PhilippinesMauritius MauritiusMemphis United States of AmericaMexico City MexicoMiami United States of AmericaMilan ItalyMinneapolis United States of AmericaMontreal CanadaMoscow RussiaMumbai IndiaNanchang ChinaNanjing ChinaNew York United States of AmericaNewcastle AustraliaNoumea New CaledoniaPalma de Mallorca SpainParis FranceParo BhutanPhoenix United States of AmericaPittsburgh United States of AmericaPrague Czech RepublicQingdao ChinaQuito EcuadorRome ItalySan’a YemenSan Francisco United States of AmericaSan Salvador El SalvadorSantiago ChileSao Paulo BrazilSeoul South KoreaShanghai ChinaSharjah United Arab EmiratesShenyang ChinaShenzhen ChinaSingapore SingaporeSydney AustraliaTaipei TaiwanTashkent UzbekistanTehran IranTokyo JapanToulouse FranceTulsa United States of AmericaTunis TunisiaVarna BulgariaVienna AustriaWashington United States of AmericaWuhan ChinaXi'an ChinaZurich Switzerland

CUSTOMER SUPPORT AROUND THE CLOCK... AROUND THE WORLD

RCSM location Country

Abu Dhabi United Arab EmiratesAjaccio FranceAlgiers AlgeriaAl-Manamah BahrainAlma-Ata KazakhstanAmman JordanAmsterdam NetherlandsAthens GreeceAuckland New ZealandBaku AzerbaijanBandar Seri Begawan BruneiBangalore IndiaBangkok ThailandBarcelona SpainBeirut LebanonBerlin GermanyBrussels BelgiumBuenos Aires ArgentinaCairo EgyptCasablanca MoroccoCharlotte United States of AmericaChengdu ChinaCologne GermanyColombo Sri LankaCopenhagen DenmarkDalian ChinaDamascus SyriaDelhi IndiaDenver United States of AmericaDetroit United States of AmericaDhaka BangladeshDoha QatarDonetsk UkraineDubai United Arab EmiratesDublin IrelandDusseldorf GermanyFort Lauderdale United States of AmericaFrankfurt GermanyGuangzhou ChinaHaikou ChinaHamburg GermanyHangzhou ChinaHanoi VietnamHelsinki FinlandHong Kong S.A.R. ChinaIndianapolis United States of AmericaIstanbul TurkeyIzmir TurkeyJakarta IndonesiaJohannesburg South AfricaKarachi PakistanKita-Kyushu JapanKuala Lumpur MalaysiaKuwait city KuwaitLarnaca CyprusLisbon Portugal

WORLDWIDEJean-Daniel Leroy VP Customer SupportTel: +33 (0)5 61 93 35 04Fax: +33 (0)5 61 93 41 01

USA/CANADAThorsten EckhoffSenior Director Customer SupportTel: +1 (703) 834 3506Fax: +1 (703) 834 3463

CHINAPeter TiarksGeneral Manager Customer SupportTel: +86 10 804 86161 Ext. 5040Fax: +86 10 804 86162 / 63

RESIDENT CUSTOMER SUPPORTADMINISTRATIONJean-Philippe GuillonDirector Resident Customer Support AdministrationTel: +33 (0)5 61 93 31 02 Fax: +33 (0)5 61 93 49 64

TECHNICAL, SPARES, TRAININGAirbus has its main spares centre in Hamburg, and regional warehouses in Frankfurt, Washington D.C., Beijing and Singapore.

Airbus operates 24 hours a day every day.AOG Technical and Spares calls.

Airbus Technical AOG Centre (AIRTAC)Tel: +33 (0)5 61 93 34 00Fax:+33 (0)5 61 93 35 [email protected]

Spares AOGs in North America should beaddressed to: Tel: +1 (703) 729 9000Fax:+1 (703) 729 4373

Spares AOGs outside North America should be addressed to:Tel: +49 (40) 50 76 3001/3002/3003Fax:+49 (40) 50 76 3011/3012/3013

Airbus Training Centre Toulouse, FranceTel: +33 (0)5 61 93 33 33Fax:+33 (0)5 61 93 20 94

Airbus Training subsidiariesMiami, USA - FloridaTel: +1 (305) 871 36 55Fax:+1 (305) 871 46 49Beijing, ChinaTel: +86 10 80 48 63 40 Fax:+86 10 80 48 65 76

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www.airbus.com

The Airbus A380 is leaps ahead. Surpassing current levels of efficiency andwith state-of-the-art cabin design, it embodies 30 years of non-stop innovationAirbus, setting the standards.

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