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VOL. 13. NO. 4, OCTOBER- DECEMBER 1988

A SERVICE PUBLICATION OF LOCKHEED·GEORGIA COMPANY. A DIVISION OF LOCKHEED CORPORATION

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Engine Compressor Washing

A SERVICE PUBLICATION OFLOCKHEED-GEORGIA COMPANYA DIVISION OFLOCKHEED CORPORATION

Associate EditorsJames A. Loftin

Robert J. R Rockwood

Vol. 13, No. 4, October-December 1986

CONTENTS

Focal PointH.M. Sohn. ManagerSupportabilityEngineering Divsion

Engine Compressor WashingRegular cleaning helps maintain com-pressor efficiency.

Is There Water in Your Dorsal!lnstdling additional drains can preventwater entrapment.

Gaging Safety by the ThreadSafe use of the ovcr~the-wing engine hoistdemands the right fasteners.

Using the Atmospheric Sump Dipstickproper filling and measuring techniqueshelp prevent lip seal damage.

Cover: Ski-equipped U.S. Navy C-130s form a vitallink in the supply lines supporting Antarctic scien-tiiic research. This year, the U.S. Navy celebratesthe 75th anniversary of naval aviation.

Published by Lockheed-Georgia Company, a Division ofLockheed C o r p o r a t i o n . I n f o r m a t i on contaIned in this issueis considered by Lockheed-Georgia Company to be accurateand authoritative: it should nor be assumed. however. t h a tthis material has received approval from any governmentalagency or military service unless it is specifically noted. Thispublication is for planning and information purposes only.and it is not to be construed as authority for making changeron aircraft or equipment, or as superseding any establishedoperational or maintenance procedures or policies. Thefollowing marks are registered and owned by LockheedCorporation: � �Hercules:� and�JetStar� Written permission must be obtained fromLockheed-Georgia Company before republishing anymaterial in this periodical. Address all communications toEditor, Service N e w s , Department 6 4 - 3 1 zone 278,Lockheed-Georgia Company. Marietta, Georgia. 30063.Copyright 1986 Lockheed Corporation.

Supportability Comes of Age

We at Lockheed-Georgia have long recognized thecentral impor-tance of high reliability and ease of maintenance in our products.Over 30 years ago, when the C-130 Hercules aircraft program wasjust beginning, formal reliability and maintainability departmentswere established for the purpose ofensuring that these character-istics received full consideration during every step of the designprocess.

All airframe manufacturers are faced with the necessity of reconciling a wide variety offactors in building a successful aircraft. In the quest to achieve an overall optimum design,reliability and maintalnability have historically been subject to the same sorts oftrade-offsasotherdesign characteristicssuch as weight, range, and speed. The final configuration hasalways been biased towardthose performance characterlstics which our customers deemedtobeparamount. In other words, we have always tried to give each of our customers exactlywhat he needed.

We still bend every effort to give our customers what they need. and today this involvesa significantlygreateremphasison reliabilityand maintainability. This message has becomeparticularly clear in the case of the U.S. Air Force, which now ranks reliability and main-tainability above initial cost, schedule, and performance in evaluating proposals for newaircraft.

An important consequence of this change in customer requirements is that reliability andmaintainability considerations at Lockheed-Georgia have now become coequal with moretraditional constraints in the design process.

Such coequality is reflected in a recent reorganization within our Engineering Branch. Inearly 1986, the position of Chief Engineer-Supportability was created. This position is atthe same organizational level as our Chief Engineer-Design,ChiefEngineer~Research andTechnology. and Chief Engineer-Electronics and Test, all of whom report directly t o ourVice President-Engineering.

Concurrent with this reorganization, we instituted:

l A strengthened and more focused supportability research and development program,directed toward advancingthe state of the art in reliability and maintainability design.

l A supportability computerization plan to establish a rapid, effective, computerizedinterface among design, logistics, and management organizations.

l A pro-active role for reliability and maintainability in the overall design process. whichincludes production drawing sign-off authority.

The goal of our new reliability and maintalnability posture is ambitious but clear: to pro-vide our customers with aircraft which are twice as reliable, but require half the maintenanceeffort.

H.M. Sohn, ManagerSupportabilityEngineering Division

E N G I N E C O M P R E S S O R

OPERATING IN SALTY ENVIRONMENTS

After flying in the salty environments found nearoceans or seashores or in areas of heavy airborneindustrial waste, operators may find that their T56/501engines are losing power prematurely. This deteriora-tion of performance, indicated by higher than normalTIT for a given torque, may be caused by a build-upof foreign material on the compressor blades. Withmany hours of continued use under these conditions,bui ld-up can increase to the point where it willsignificantly disturb the flow of air across the com-pressor rotor blades and stator vanes, resulting inreduced compressor output for a given rpm.

Routine liquid cleaning or water wash of the com-pressor will normally remove these deposits and restorecompressor efficiency. It should always be kept in mind,however, that power losses cannot arbitrarily be attri-buted to a dirty compressor; all such cases must be fullyinvestigated.

Field Cleaning

T.O. 2J-T56-101 and the applicable Allison main-tenance manual describe methods of field cleaning theengine compressor stator vanes and rotor blaces by useof water or chemical solution liquid cleaning, or, fortough jobs, abrasive cleaning (using ground walnut hullsor apricot pits, for example).

Lockheed SERVICE NEWS V13N4 3

The procedure recommended in cases where com-pressor contamination is suspected or confirmed byvisual inspection, is first to liquid clean the compressor,then to do a performance check. If the performancecheck reveals continued reduction in engine compressoroutput, the abrasive cleaning procedure should beconsidered.

Frequency

Aircraft operated in a sea air environment requiremore frequent applications to remove the corrosivedeposits from the internal surfaces of the compressorsection. Note that the salt water mist or spray along acoastline decreases rapidly in the first half mile fromthe shoreline and at altitudes over 500 feet. Of coursethe rate of this reduction will vary according to climate,wind direction, and velocity. For this reason, aircraftoperated anywhere in the vicinity of a coastline shouldhave corrosion preventive washes of the compressorsection as detailed below.

Ingested Salt Water

An engine that has salt water introduced directly intothe compressor as a result of direct wave splash oroperation near a seashore where there is wind pickupof salt water mist or spray should have a compressorwater wash performed after the last flight of the day.

No Direct Exposure

Engines on aircraft located near sea air environmentsbut not directly exposed to sea air, in other words notwithin one-half mile of the coastline or less than 500feet above the water during flight or ground operations,should undergo air compressor liquid cleaning at leastevery 15 days unless inspection reveals the need for morefrequent applications.

Inactive Engines

If an engine is to be inactive for more than a few daysafter operation in a salty environment, the compressorshould be liquid cleaned after the last flight prior to theperiod of inactivity. After it is cleaned, the engine maybe considered relatively safe from the corrosive effectsof the salty environment for about two weeks. Afterthis time, it will be necessary to inspect the compressorto determine if there is evidence of corrosive deposits.If such deposits are found, the compressor should havean additional liquid cleaning whether the engine is tobe returned to service immediately or only after con-tinued inactivity.

If an engine in a sea air environment has not beenoperated for a period of three days or more, the com-pressor should be liquid cleaned before the engine isreturned to normal operation.

Note that T.O. 2J-T56-101 contains proceduralinstructions for compressor liquid cleaning for removalof oil and other deposits which adhere to blade and vanesurfaces and reduce compressor efficiency. Aircraft notequipped with the overboard drain for the propellerscupper will require more frequent cleaning due to pro-peller oil leakage into the inlet duct.

Corrosion Control

Constant vigilance and strict adherence to propercleaning procedures must be maintained in order to pre-vent corrosion deposits from forming inside the com-pressor section of the engine.

When an aircraft is to be idle for a period of time,all engine orifices (intake and exhaust openings, etc.)should be closed using the appropriate covers or plugsaccording to established procedures.

An engine which has been inactive and hasaccumulated internal moisture as a result of rain leakageor condensation should be run as soon as possible untilit is dried out.

EQUIPMENT AND MATERIALS

It is important to utilize proper equipment andmaterials when performing compressor liquid cleaningoperations. Failure to do so may result in a furtherreduction in compressor efficiency or damage to thecompressor.

The specific type of equipment is not as importantas equipment capabilities. The equipment must deliverthe water or chemical solution to the engine inlet witha flow rate capability of 10 gallons per minute. In addi-tion, there is a need for a dry air supply at a minimumof 50 psig to hold the compressor bleed valves closedduring water wash application.

The following equipment is listed in SMP 515E:

Cleaning and Preservation Unit, PN LTCT23980-01, manufactured by AVCO-Lycoming.

Jet Aircraft Engine Corrosion Control SprayingUnit, PN 76E04000-30A, manufactured by MetricSystems Corporation.

Lockheed SERVICE NEWS V13N4

Part No. 6796852Compressor Salt Deposit Spray Cleaning PressurizedTank Noncorrosive, Nonflammable Cleaners

The following equipment is listed in the Allison The recommended chemicals and mixtures for liquidmanuals: cleaning of the engine compressor are as follows:

l Corrosion Control Water Wash Trai ler, PN l6796852/ MIL-S-83189A (FSN 1730-00-403-3028),available from Allison. Provides cleaning agentunder pressure.

l Model 299 Spray Mix Applicator, manufactured byB and B Chemical Company. .

Many operators, however, have devised their ownversion of the required equipment, customized to suittheir specific needs.

B and B 3100, FSN 6X50-00-282-7597 for 55gallons/FSN 6850-00-181-7594 for 5 gallons, B andB Chemicals Company, Inc., P.O. Box 796, Miami,Florida 33166. Mix at a ratio of one part chemicalto four parts water.

Penetone 19, Penetone Corporation, 74 HudsonAvenue, Tenafly, New Jersey 07670. Mix in a ratioof from one part chemical to four parts water to fullstrength, depending on the degree of enginecontamination.


l Turco 4217, 5884, and 5884-AG, Turco Products,24600 South Main Street, Carson, California 90749.Mix in a ratio of one part chemical to four partswater.

Water Supply

Water suitable for washing the engine compressormust be of drinkable quality. It must be of sufficientpressure and volume to provide a flow rate of 10 gallonsper minute.

The chemical purity of the water is also important.Most bottled “mineral” water found in stores hasaround 500 parts per million total dissolved solids.Water with greater than 472 parts per million totaldissolved solids can eventually degrade engine perfor-mance. Furthermore, water with a chloride content ofgreater than 20 parts per million can cause corrosionin the engine structure and should not be used.

Scale Build-Up

Studies have shown that as the water passes throughthe compressor section during the liquid cleaning andrinse procedure, the dissolved solids in the water areseparated from the water as it is vaporized. As minuteairborne particles these solids are then deposited on thecompressor blades. Such deposit results in a build-upor “scale” that is similar in appearance to the precipitatefound in the bottom of a tea kettle after hard water hasbeen boiled in it.

This scale can change the aerodynamic characteristicsof the blades, resulting in increased drag, turbulent

Part No. LTCT 23980-01Cleaning and Preservation UnitManufactured by AVCO-Lycoming

airflow, or perhaps even cavitation (compressor stall)--just like the salt deposits that are the reason for thecompressor wash in the first place.

There are two factors that determine the rate at whicha particular engine will have scale build-up in its com-pressor section: the amount of wash water containingdissolved solids that is used in cleaning the compressor,and how long the engine has operated.

The degree of scale build-up tends to be directly pro-portional to the amount of water ingested by the engineduring the cleaning process. For this reason it is impor-tant to be aware of the quantity of water called for inthe compressor liquid cleaning instructions found in theAllison maintenance manual or in T.O. IC-l30H-2-4,Section Il.

The scale wears away or flakes off during engineoperation. The longer the engine is operated, the lessthe scale build-up. The scale will accumulate only untila dynamic balance is established between the build-upincurred during water rinse and the wearing away duringengine operation. To remove the scale from the com-pressor requires an abrasive cleaning procedure asspecified in the Allison manual or in T.O. IC-130-2-4,Section 11-41.

CLEANING PROCEDURES

The instructions in the applicable maintenancemanual should be carefully followed when performingcompressor water wash operations.

While motoring an engine by the starter during thecleaning procedure, remember that the starter presentsthe same safety hazard as an engine that is running. Besure to take appropriate safety precautions. Also, bcaware of the starter duty cycle: the procedure in theAllison maintenance manual recommends that theengine be motored to maximum available starter rpmfor approximately 30 seconds. (Note that the procedurein T.O. lC-130H-1 specifies a maximum cycle of 1minute starter ON followed by 1 minute OFF.) Thestarter should not be operated longer than 60 secondsat a time.

Ensure that the condition lever for the engine is inthe GROUND STOP position so that the ignitionsystem will bc deactivated during engine motoring.

Always allow the engine to cool for at least 4.5minutes after shutdown before performing the waterwash or chemical cleaning procedure. Note that if the

6 Lockheed SERVICE NEWS V13N4

Part No. 76E04000-30AJet Aircraft Engine Corrosion Control Spraying UnitManufactured by Metric Systems Corporation

chemical solution is injected into the engine while theengine is too hot, the solution may congeal on theblades, vanes, and valves, requiring a repetition of thecleaning and rinse cycle. Also note that the flash pointfor some of the chemical cleaning agents may be as lowas 150 degrees F (66 degrees C) in concentrated form.

Salts and other corrosive, water-soluble depositsshould be removed from the engine inlet duct, air inlethousing struts, and bands of the inlet guide vanes byflushing with a fine spray of fresh water. Approximately10 gallons of the spray per engine should be a sufficientquantity of water for accomplishing this.

About 50 psi of compressed air from an external dryair source (air bottle or portable air compressor) isrequired to hold the 5th-and 10th~stage bleed air valvesclosed during the cleaning procedure. Be sure to capthe outlet fitting of the speed-sensitive valve assemblywhen the air hose is disconnected. Install an appropriateuncontaminated union in the hose so that the com-pressed air source may be plumbed in at that point.

If the engine performance remains at an unsatisfac-tory level after the liquid cleaning process has beenaccomplished, perform a thorough visual inspection forcompressor erosion through the compressor bleed valveports. Should the inspection reveal an eroded com-pressor, do not perform abrasive cleaning: abrasivecleaning of an eroded compressor may further reducethe performance of the engine. If, however, the inspec-tion reveals no compressor erosion, then perform theabrasive cleaning procedure as described in the Allisonmaintenance manual or in Section 11 of T.O. lC-130H-2-4.

Be sure that the engine has been restored to its normalconfiguration prior to drying out and additional per-formance checks.

Periodic liquid cleaning of the engine compressor isan important consideration in every maintenance pro-gram. Such maintenance will prevent unnecessarydeterioration of engine performance that can resultfrom compressor contamination.

Always rinse the compressor thoroughly with waterafter a chemical cleaning has been done. While repeat-ing the engine motoring sequence, rinse until the watercoming out the tailpipe is clean.

7

Hercules dorsal fin has a new drainage provision toprevent water entrapment. by Harold Singletary, Staff Engineer

Materials and Processes

WATER IN THE DORSAL FIN DORSAL DRAINAGE

Several reports of water entrapment inside the dorsalfin have prompted a production change at Hercules air-craft Lockheed serial number LAC 5058 for drainageprovisions in the forward end of the dorsal.

How does water get into the dorsal and becometrapped? One would think that the dorsal would staydry since the flanges on the dorsal and vertical stabilizerwhich mate to the upper surface of the fuselage andhorizontal stabilizer are fay surface sealed.

If, however, the airplane is parked in a nose-lowattitude on uneven ground such as a slope on the washrack, rain and washing solutions will flow forward fromthe rudder well over the horizontal stabilizer into thedorsal. There the water will remain until the attitudeof the nose is raised sufficiently to allow the fluid toflow aft and out by way of the route of entry.

When a Hercules aircraft remains on the ground ina nose-low attitude for several days in rainy weather,the accumulation of water in the dorsal can be con-siderable. One incident of water entrapment resulted indrainage of about 40 gallons of liquid from the dorsalinto the cargo compartment when a bolt that securesthe cargo door uplock was removed.

LAC 5058 and up

Drainage provisions in the dorsal fin on LAC 5058and up are authorized by Lockheed drawing 337651.These provisions consist of two parallel joggles in thedorsal flange approximately four inches behind theforward end of the dorsal. The joggles, which look likebumps in the flange, produce an opening between thefuselage skin and flange of 0.12 inches in height and1.5 inches in length.

Aircraft prior to LAC 5058

Operators with geographical and environmental con-ditions which are conducive to water collection in thedorsal should consider the value of adding drain outletsnear the forward end of the dorsal on their Herculesaircraft built prior to LAC 5058. They have a choiceof drain installations, since the following three pro-cedures have been authorized by Lockheed engineeringfor in-service Hercules aircraft.

Procedure 1

The first offers the most efficient dorsal fin drainageprovision. This is the hole-and-slot passage illustrated


DOUBLER

Figure I. Dorsal Fin Drain Provision: Procedure 1

in Figure 1. Since the installed drainage points are closeto the forward end of the dorsal, and the drain slot.extends to the fuselage presssure skin, the followinginstallation provides nearly complete drainage:

I. Remove existing rivets No. 8 and No. 9 fromeach side of the forward end of the dorsal.

2. Drill a 1/4-inch diameter drain hole centeredbetween rivets No. 8 and No. 9.

3.

4.

5.

6.

7.

8.

Slot the flange of the dorsal in line with the holeto the outboard end of the flange.

Fabricate two doublers as shown in Figure 1from 0.040-inch 2024-T3 clad aluminum alloysheet.

Hand-form the doublers with a 0.12-inch radiusto nest on top of the dorsal.

Finish the doublers with epoxy primer.

Install the doublers wet with MIL-S-81733inhibitive sealant on the surfaces that mate withthe dorsal and pressure skins, using fiveM7885/2-4-2 blind fasteners (three added holesand two existing holes) wet with MIL-S-81733sealant.

Topcoat the doubler installations with two coatsof MIL-C-833286 polyurethane of the same coloras the surface adjacent to the doublers.

Procedure 2

Procedure 2 promotes dorsal fin drainage, but notas effectively as the hole-and-slot passage describedabove. Since the installed drain hole is about l/2 inchabove the low point, the collected water will not draincompletely. Simpler than the hole and slot procedure,the following procedure calls for drilling two holes inthe dorsal fin:

I . Drill a I /Cinch diameter hole in each side of the

0.25 DIA HOLE (TYP)FS 737 ABOVE FLANGE RADIUS

RIVET NO. 8

I I I 1

9.0RIVET NO. 9

Figure 2. Dorsal Fin Drain Provision: Procedure 2


GAGINGAFETY

BY THETHREADh I

Over-the-wing engine hoist assemblies are familiarpieces of equipment (see Figure 1). Available in severaldifferent configurations, they have been in general useby Hercules aircraft operators throughout the world formany years. The very familiarity of these convenienthoists is a tribute to the practicality of the design.Familiarity can be a mixed blessing, however, andnowhere is this more true than where matters of safetyare concerned.

When using an over-the-wing engine hoist, it isextremely important that careful attention be paid toall the details of the way the hoist is attached to thewing. The use of bolts of the wrong type and griplength,improper installation techniques, or the presenceof corroded or damaged threads on the bolts or in thenuts of the attach points might result in the hoist beinginadequately secured. This could pose a significantsafety hazard, with potential for damage to equipmentor injury to personnel.

There are two specific areas involving the over-the-wing hoist attachment point hardware that require strictattention to proper maintenance practices.

The first has to do with the attach points themselves.The fasteners that are installed in the hoist attach pointswhen the hoist is not in use are standard structuralfasteners and must be of the proper length to preventrust or corrosion of the barrel nut due to exposed

Eng ine t

threads. Figuretions to bc use

When Using the

O v e r - t h e - W i n g

o i s t

1d

shows the various bolt sizes and loca-on specific Hercules aircraft model

designations. Shown in Figure 2 are typical nut plateand barrel nut locations.

When installing the structural fasteners after usingthe over-the-wing hoist, remember that the fastenersshould be installed wet with Products Research andChemical Company Low-Adhesive Sealant No.PR1403G, which contains a rust inhibitor. If thePR1403G sealant is not available, use MIL-S-8784


This could be dangerous assumption, however, if theinstalled bolt is not of the proper length. For this reason,it is highly advisable to measure the individual bolt loca-tions at each attach point to verify the minimum lengthneeded.

There are several methods by which this may be

Figure 3. PN 3403141 Bolt and Gage Setaccomplished, but the quickest and easiest is to use thetool specifically developed for this job. The PN 3403141

sealant. MIL-S-8784 does not contain a rust inhibitor,bolt and gage set (see Figure 3) accurately measures the

so apply LPS-3 to the threads prior to sealantbolt hole on the wing and indicate the size and length

application.of the bolts needed.

The other hardware to be considered when using theManufactured by Lockheed-Georgia Company, the

over-the-wing engine hoist are the bolts used to attachPN 3403141 bolt and gage set consists of gages for the

the hoist to the wing. It is critical that these bolts bevarious size and lengths of bolts and a gage pin to

of the proper grip length, particularly those installedmeasure depth. The gages are dimensioned to provide

into the aft attach point barrel nuts. The bolts at thisbolt tolerances. The pin has a sliding sleeve for taking

location handle much of the tension load imposed bybolt hole depth measurements. The length can be deter-

the weight supported by the hoist. Bolts of insufficientmined on the gage. The set components are tied together

grip length at the aft bracket attach points may pull outwith retention cables and are stored in a pouch which

of the wing under load.can be attached to the over-the-wing hoist assembly.

The instructions that apply to the hoists typically Whatever measurement method you decide to use,

specify that NAS 6604 or NAS 6605 bolts be used,do measure. And do use bolts of the correct type and

depending on mounting point location. As far as boltof sufficient grip length to secure the hoist properly.

length is concerned, it might appear that the correct sizePlay it safe. Don’t let familiarity breed contempt for

bolt to use for attaching the hoist to the wing wouldsafety for you or your organization.

be approximately l/2 inch longer than the thread-protecting bolt that was removed from a particular loca-tion. After all, the hoist attach bracket PN 341288 thatis used on all installations has a total thickness of 0.525inch (bracket plus pad).

Figure 2. Over-the-Wing Hoist Attach Points(Typical)


Using the

ATMOSPHERIC SUMP

An atmospheric sump dipstick was incorporated inthe pump housing assembly of the 54H60 propellersome years ago to make it possible to check or servicethe propeller control assembly oil quantity more easilyand more accurately than with the original dipstick,which measured the oil quantity in the pressurizedsump.

Although the authorized maintenance manuals stillcontain instructions for determining propeller oilquantity using either dipstick, most 54H60 propellersmanufactured in recent years have omitted thepressurized sump dipstick entirely. For these units, thereis of course no choice as to which dipstick to use. Buteven for other units which contain both dipsticks, theatmospheric sump dipstick offers the best method ofestablishing a safe operating level for the prop oil. Tounderstand better why this is so, it is useful to reviewhow the system works.

PRESSURIZED SUMP

There are two oil reservoirs in the propeller controloil system, the pressurized sump and the atmosphericsump. The pressurized sump is the reservoir for themain, standby, and auxiliary (feather) pumps. To pre-vent cavitation of the pumps at high altitude, this reser-voir is pressurized at 15 to 20 psi.

The hydraulic pressure required for operating the pro-peller pitch changing mechanism is supplied by thepumps located in the pressurized sump. Most of the out-put from the pumps returns to this reservoir. However,return oil from the pitchlock regulator pressurizing andregulating valve ends up in the atmospheric sump byway of the propeller barrel and beta feedback gear. Oilthat is used for lubrication or involved in internalleakage also drains back into the atmospheric sump.

ATMOSPHERIC SUMP

The atmospheric sump is the reservoir for the mainand auxiliary scavenge pumps. These pumps keep thepressurized sump supplied with oil and maintain I5 t o20 psi pressure in the sump.

It is important that the oil level in the atmosphericsump be kept at the correct level for the scavenge pumpsto perform properly. If the oil level in the atmosphericsump is allowed to become too low, the scavenge pumpswill cavitate, introducing air into the oil system. Theresult can be inadequate oil in the pressurized sump.If the pressurized sump reaches a 2-quart low condi-tion, a propeller oil low indication will be given. Thiscould mean having to shut down an engine and feathera prop.

On the other hand, if the oil level in the atmospheric

most of the confusion that used to arise concerning theinterpretation of dipstick readings. However, improperchecking and servicing of the atmospheric sump is stilla cause of propeller problems from time to time. Theseproblems are typically the result of overservicing ratherthan underservicing. As far as propeller control oil levelis concerned, it is important to bear in mind that thisis one area where more is definitely not better.

CHECKING PROPELLER CONTROL FLUIDLEVEL

Using the atmospheric sump dipstick is the perferredmethod of determining the propeller control oil level.A brief review of the routine propeller servicing pro-cedure using the atmospheric sump dipstick (oil levelindicator) is given below. As always, consult the appro-priate maintenance publication before undertaking thisactivity on the aircraft.

LEVEL

ORIGINAL

F U L L - I

C U R R E N T

sump is too high, other types of problems can develop. Before You Start. . .The usual result of overservicing the propeller controlassembly is that oil is forced out of the propeller around There are several things that should be kept in mindthe lip seal. This leads to lip seal damage and continuing before you proceed with the oil level checkingpropeller oil leakage. procedure.

READING THE DIPSTICK

The original atmospheric sump dipstick or oil levelindicator bore markings for a PRE FILL range and anOP LEVEL range. The current dipstick has only aFULL level indication. Hamilton Standard ServiceBulletin HS Code 54H60 No. 101, Revision 1, datedOctober 15, 1981, provided instructions and authoriza-tion for changing the earlier dipstick markings on com-mercial aircraft to the current configuration.

Similarly, T.O. lC-130B-2-11 and T.O. lC-130H-2-11 contain instructions for modifying the originaldipsticks on military aircraft to remove all but the lowestof the OP LEVEL markings. The remaining markserves the same purpose and measures the same oil level

First, note that it requires two people to carry outthe procedure properly, one in the flight station and oneat the propeller. Be sure a qualified assistant is availablebefore you begin.

Next, remember that when you check the propellercontrol oil level, the oil in the unit should be at itsnormal operating temperature. If the weather is verycold outside, 0 degrees C (32 degrees F) or below, andthe propeller has been exposed to low temperatures forawhile, it will also be necessary to warm the propellerhub (using warm air or by running the engine) until theoil temperature is 60 to 80 degrees C. If this is notaccomplished, propeller blade seal damage and oilleakage will result when the propeller is cycled duringthe servicing procedure.

as the FULL marking on newer atmospheric sumpdipsticks. Take care to see that engine oil is not used in the pro-

peller control system. Except for a few special applica-Simplifying the dipstick markings has eliminated tions, hydraulic fluid specification MIL-H-83282 is used


in all aircraft maintained according to U.S. militaryspecifications. Most commercial Hercules aircraft usehydraulic fluid specification MIL-H-5606 for propellersand other applications where hydraulic fluid is specified.

If any engine oil is accidentally introduced into thepropeller control and circulated thorugh the unit (inother words, the propeller has been operated since theengine oil was added), it will be necessary to removethe propeller and control for replacement of all per-formed packaging.

Be sure to take all necessary precautions to keepforeign substances such as rain, snow, sand, or blow-ing dust from entering the unit during servicing.

It is necessary to run the auxiliary pump during thechecking and servicing procedure in order to cycle thepropeller and pressurize the pressurized sump with fluid.Be sure to observe the duty cycle of the auxiliary pumpmotor when carrying out this operation.

The pump motor may be operated up to a maximumof 60 seconds at a time, followed by a cooling-off periodequal to the time of operation. For example, on for 40seconds followed by off for 40 seconds. The normalmaximum total running time during any half-hourperiod is two minutes, but the motor may be operatedas long as the temperature of the motor body does notexceed 150 degrees F, or 65.6 degrees C. An easy wayto monitor the motor temperature is to feel the motorbody with your bare hand. If it is too hot to keep yourhand on for more than 5 seconds, it is time to let themotor cool off for awhile.

To operate the auxiliary pump and change blade pitchduring servicing, select the desired blade pitch angle withthe throttle lever while holding the appropriate con-dition lever in the AIR START position to energize thepump motor.

Feathering of the propeller may be accomplished bymoving the condition lever to the FEATHER position.The prop may also be feathered by pulling out the fireemergency handle. The operation of the auxiliary pumpmotor and resulting blade pitch operation may bestopped at any time by moving the condition lever tothe GROUND STOP position or pushing in the fireemergency handle.

The master propeller low oil quantity light on theengine instrument panel has the function of illuminatingto warn the flight crew when one or more propellersare approximately 2 quarts low on oil in the pressurized

sump. There are four propeller low oil warning lightson the copilot’s side shelf, one for each propeller, toidentify which of the propellers has low oil. If one ofthese lights illuminates while the auxiliary pump is beingoperated during the servicing procedure, stop the motorand add fluid to the propeller control atmosphericsump.

When oil is to be added to the propeller control,remove the top left forward engine cowling, remove thevalve housing cover cap on the left side of the controlhousing, and add the required amount. Be careful notto overfill. One inch on the dipstick is equal to approx-imately 14 fluid ounces. If it is necessary to remove oilfrom the propeller control because of overfilling, forexample, siphon it from the pressurized sump.

When adding fluid to the propeller control, exercisecare not to get fluid on the electrical brush assemblyor the deicer contact rings. Fluid spilled in these areasmay cause electrical shorting of the brushes and deicerrings, and scorching of the brush housing. If some pro-peller oil accidently comes in contact with the brushassembly, clean the area with Federal specificationPD-680, Type II, solvent. Be sure the area is dry againbefore running the engine.

ATMOSPHERIC SUMP OIL LEVEL C H E C KPROCEDURE

1. Connect an external source of AC power tothe airplane.

2. Remove the top right forward engine cowling(or open the access door provided on later aircraft).

3. If more than 30 minutes has elapsed since thelast engine run, cycle the propeller from FEATHER toREVERSE at least 3 times, stopping with the throttleat GROUND START for the commercial model andGROUND IDLE for the military model. Hold the con-dition lever at the AIR START position for at least 20seconds after the propeller reaches the GROUNDSTART (GROUND IDLE for military) position.

4. With the auxiliary pump still operating,remove the atmospheric sump dipstick and wipe it witha clean, lint-free cloth. Insert and lock the dipstick inits tube. Then remove the dipstick and check the oillevel. The fluid level should be indicated on the dipstick,but should not exceed the FULL (or lower OP LEVEL)mark. Add or remove oil as necessary to achieve thisindication.

5. Restore the engine to normal configuration.


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