tA

P.1 LEVELTM 79-1 SY 6

5o

AIRCRAFT ENGINE DRIVEN ACCESSORY

SHAFT COUPLING IMPROVEMENTS

USING HIGH-STRENGTH NONMETALLIC ADAPTER/BUSHINGS

SECOND PROGRESS REPORT

C)

Mr. Aleck Loker

C.1 Systems Engineering Test Directorate 1i=,DDC [

ZO April 1979=MAY 16 1979

D

NT OF Approved for Public Release; Distribution Unlimited.

-j~ I )NAVAL AIR TEST CENTER

, TE PATUXENT RIVER, MARYLAND,, iiL.

UNCLASSIFTFT)SECURITY CLASSIFICATION OF THIS PAGE ("oIhn Data Enteled)' j I.O .-, - .. .

REPORTNSREPORT DOCUMENTATION PAGE BEFORE COMPLETING FORM

1. REPORT H910 R T GOVT ACCESSION No. 3. RECIPIENT'S CATALOG NUMBER- _ 'TM 79-1-SY

- ... ... .. , '. 5. TYPE OF REPORT & PERIOD COVERED

iAIRCRAFT EN GINE DRIVEN-ACCESSORY ,HAFT.OU PLING rIMPROVEM ENTS j SIN G 5IGH-J TR EN GTH

4 ONMETA C APTER/B6 SHIN S. tt Iq . . 6 PERFORMING ORG. REPORT NUMBER

7. AUTH 8. CONTRAT OR GRANT NUMBER(s)

zkfltAI'EC K bk KER 4/2Q /.9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK

AREA & WORK UNIT NUMBERS

SYSTEMS ENGINEERING TEST DIRECTORATENAVAL AIR TEST CENTERPATUXENT RIVER, MARYLAND 20670

11 CONTROLLING OFFICE NAME AND ADDRESS

SYSTEMS ENGINEERING TEST DIRECTORATE ?__ ____ _____NAVAL AIR TEST CENTER F)3.NUwftI!1

PATUXENT RIVER, MARYLAND 20670 4714 MONITORING AGENCY NAME a ADORESS(II different Irom Controlling Office) 15. SECURITY CLASS. (of thi* report)

UNCLASSIFIED

I5a DECLASSIFICATION/OOWNGRADINGSCHEDULE

16 DISTRIBUTION STATEMENT (of this Report)

APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED.

17 DISTRIBUTION STATEMENT (of the abtract entered in Block 20, if diflerent from Reporto

18. SUPPLEMENTARY NOTES

19 KEY WORDS (Continue on reverse aide if necessary and identify by block number)

r SHAFT COUPLINGS RELIABILITYSPLINED SHAFTS GENERATOR DRIVE SHAFTSINVOLUTE SPLINES STARTER DRIVE SHAFTSCIRCULAR SPLINES HYDRAULIC PUMP DRIVE SHAFTSAIRCRAFT POWER TRANSMISSION

0 ABSTRACT (Continue on reverse aide If necessary and Identify by block number)

Engine driven accessories, such as generators, starters, and pumps, are commonlyconnected to their respective power takeoff shafts by splined couplings. These shaftcouplings, which allow rapid installation and removal of the accessory, are capable of hightorque transmission and are considered to be self-centering. However, because of their

rapid wear and failure rate, NAVAIRTESTCEN has engaged in a continuing spline couplingimprovement program over the past 11 years. An outgrowth of this program has been thedevelopment of the new high-strength nonmetallic spline coupling adapter/bushing

technolog y . Previous Technical Memoranda, TM 76-1 SY and TM 78-1 SY, condensed the

DD I JAN 73 1473 EDITION OF I NOV 65 IS OBSOLETE i_", ________________NCLASSIFIED ,i. .S.EC.URITY.CLASSI.FICATIO.N OF THIS AE (When Date FI,

S CURITY CLASSIFICATION OF THIS PAGE(When Data Entered)

esults of these coupling improvement efforts into a description of two basic splinecoupling designs (crowned circular toothed and flat toothed splines), explained theirapparent success, and presented limited application and manufacturing information.

This report presents a summary of the new coupling designs which have been evaluated orare planned for future tests. Previously unpublished test data and the latest applicableMilitary Standard Drawings are also contained therein.

Actual flight operations totaling 68,000 hr on 10 differ t drive s nonmetallic couplingdesigns have verified the value of this new coupling technology.

Hydraulic pump endurance testing indicates that properly applied nonmeta i splineadapters can endure millions of stress cycles.

Air turbine starLer tests have established that the low cycle fatigue limit for the circularspline design approaches the static torsional limit of the nonmetallic adapter.

Wear of the metal or plastic coupling parts is negligible even when the load approachesthe torsional limit of the nonmetallic adapter.

Preliminary acoustic tests of a hydraulic pump driven through a nonmetallic couplingdemonstrated a 9 dB reduction in the predominant audible frequency.

New applications will continue to be tested. Performance standards, an adapterspecification, and alternate nonmetallic material qualification will be emphasized infuture programs.

The circular spline design (U.S. Patent Number 3,620,043 of 16 November 1971) has beenassigned to ARINC Research Corporation with royalty free rights to the Department ofDefense. The other nonmetallic spline coupling design (U.S. Patent Number 4,098,096 of4 July 1978) has been assigned to the United States Government.

I

UNCLASSIFIED

SECURITY CLASSIFICATION OF THIS PAGE(When Dat. Entered)

PREFACE "

Prcuious Technical ox;- a, 476-1 SY and TM 78-1 SY, described the

ucessiul elimination of spline coupling wear and the attenaant reiaityimprovement made possible by new high-strength nonmetallic shaft couplings. Thisreport presumes a knowledge of the basic spline coupling mechanism, the factorsleading to spline wear, and the design principles which are fundamental to the newnonmetallic coupling. Appropriate additional references are included in this reportfor the reader who wants more extensive background information pertaining to thespline coupling problem.

The continued and growing interest in this new shaft coupling technique expressedby the aerospace and industrial mechanical design community has resulted innumerous requests for additional design, test, and application information. ThisTechnical Memorandum is intended to provide an update on the spline couplingimprovement efforts at NAVAIRTESTCEN and to provide application orienteddesign information as a supplement to the basic coupling configurations previouslypublished.

APPROVED FOR RELEASE

./JOHN B, PARADIS__ Technical Director

Naval Air Test Center

13 -Ai2Z1 LEVBo Dll111 N. . .............. F r

il IIJIIITIN/AT IAUI.I ...... ............... IND - Al"[ [r'[[- : -

" l~t AVA.. 'W/' i. i ),AY 16 1979

TM 79-1 SY

TABLE OF CONTENTS

Page No.

REPORT DOCUMENTATION PAGE i

PREFACE iii

TABLE OF CONTENTS iv

LIST OF ILLUSTRATIONS v

INTRODUCTION 1BACKGROUND 1PURPOSE 4

SUMMARY OF 3PLINE COUPLING APPLICATIONS 4EXTERNAL SPLINE ADAPTER CONFIGURATIONS 4INTERNAL SPLINE ADAPTER CONFIGURATIONS 7TACHOMETER GENERATOR SQUARE DRIVE SHAFT 7

SUMMARY OF RECENT TEST RESULTS 9CH-53E HYDRAULIC PUMP FATIGUE TEST 9CH-53E HYDRAULIC PUMP SHAFT ENDURANCE TEST 12HYDRAULIC PUMP ACOUSTIC TEST 19AIR TURBINE STARTER TESTS 23ADDITIONAL NONMETALLIC SPLINE ADAPTER DATA Z5MILITARY STANDARD DRAWINGS 29

CONCLUSIONS 30PLANS 30

REFERENCES 31

APPENDIX A - NONMETALLIC SPLINE COUPLING MILITARY 33STANDARD DRAWINGS

1v1iv

TM 79-I SY

LIST OF ILLUSTRATIONS

Table I Status of Nonmetallic Shaft Coupling Applications

Table II Ultimate Static Torque Load for Various Nonmetallic AdapterConfigurations (Room Temperature Performance, Values in ft-Ib)

Figure 1 Aircraft Hydraulic Pump and Shaft Coupling HardwareIllustrating Typically Worn Standard Involute Splines and-theNew Nonmetallic Spline Modification

Figure 2 Laboratory Induced Spline Wear of Grease Lubricated SplinesShowing the Effect of Spline Coupling Misalignment

Figure 3 Laboratory Induced Spline Wear of Unlubricated hIternally andExternally Involute-Splined, Polyimide Plastic Bushing Showingthe Reduction in Wear Rate

Figure 4 A Comparison of Two Types of Nonmetallic Shaft CouplingsNoting the Two Preferred Methods of Achieving Retention andCompressive Preload

Figure 5 Engine Driven Tachometer-Generator Illustrating theNonmetallic Square Drive Bushing Installation

Figure 6 Shaft Torsional Fatigue Test Apparatus Using an AircraftElectrical Starter as the Prime Mover

Figure 7 Typical Torsional Load Cycles Applied to Test Shaft CouplingsDuring Shaft Torsional Fatigue Evaluations

Figure 8 Proposed Aircraft Hydraulic Pump Nonmetallic ShaftCouplings as Tested for the CH-53E

Figure 9 CH-53E Hydraulic Pump Endurance Test LaboratoryInstallation Illustrating the Various Hydraulic Components

Figure 10 CH-53E Hydraulic Pump Endurance Test Diagram Showing theRelationship of the Various Hydraulic Components

Figure 11 CII-53E Hydraulic Punp Endurance 'rest Recorded LoadProfile Showing the Cyclic Variation of the Test Parameters

Figure 1Z CH-53E Hydraulic Pump Endurance 'rest Recorded LoadProfile, Time Domain Expanded to Show Individual LoadCycles

Figure 13 CH-53E Hydraulic Pump Endurance Test Recorded LoadProfile Showing the Torque Peak Experienced DuringSimulated Engine Start-up and Shut-down

vVU

TM 79-1 SY

LIST OF ILLUSTRATIONS (CONT'D)

Figure 14 0.6875 in (17.5 mm) Pitch Diameter Spline Adapter Removedlfromn the Enveloping Outer Shaft Spline Following 4.3 MillionTorsional Load Cycles

Figure 15 Location of the Acoustic Measuremnint Equipment withRespect to the C11-53E3 Hydraulic Pump and Drive Stand

Figure 16 Comparison of Octavo Band Analysis of Acoustic DataRecorded with C11-53E Hlydraulic Pump Driven Through aStandard Steel havolute Coupling and Through at NonmetallicCoupling

Figure 17 Comparison of Torsional Oscillations with the CH-53EHydraulic Pump Driv en Through a Standard Steel InvoluteCoupling and Through a Nonmetallic Couipling

Figure 1S T-56 Engine Air Turbine Starter Nonmetallic CouplingComponents Followving 1200 Start Cycles and 1000 HirContinuous Operation tit 14,000 RPM

Figure 19 Nonmetallic Adapter Damaged During 1200 Cycles of the F- 14Engine, Air T1urbine Starter

Figure Z0 Comparison of thle Two T ypical Nonmetallic Adapter FailureModes: Slip/Compressive Deformato Associatdz t h

Circular Spline~s and Fracture Associated wvith thle Flat-SidedSplines

Figure 21 Illustration of the Torque, Compressivo and Shear LoadsInherent in Three Spline TIypes Showing the Relatively HigherShear Load Resulting from thle Cire.-lar Splino and Showving thleLoad Bearing Aron Av'ailable in Each Design

vi

TM 79-1 SY

INTRODUCTION

1. Engine driven accessories, such as generators starters, and pumps, arecommonly connected to their respective power takeoff shafts by splined couplings.NAVAITZ.TESTCEN has engaged in a continuing spline coupling improvementprogrr.r during the past 11 years. Reference I ntroduced the new splinetech-iology which resulted from these efforts and explained how these nonmetallicspline couplings may improve accessory power system reliability. Reference 2presented additional application oriented information such as manufacturing detailsand specific design information. This report presents a summary of the newcoupling designs which have been evaluated or are planned for future tests.Previously unpublished test data and .the latest Military Standard Drawings are alsocontained herein.

BACKGROUND

2. Spline couplings have been chosen by mechanical equipment designers forconnecting driven accessories to power takeoffs because of their ability to transmithigh torque, their purported self-centering tendency, and axial freedom ofmovement which eases installation and removal. However, the demonstrated highwear rates of conventional spline couplings used with engine driven accessories,such as hydraulic and fuel pumps, generators, and engine starters, frequently causeexpensive and tine-consuming maintenance or overhaul action and affectpropulsion system reliability. The causes of spline wear, discussed in detail inreference 1, can be summarized as an inability of tho coupling to adequatelyaccommodate misalignment, a difficulty in maintaining sufficient lubrication, and abasic susceptibility to the process of fretting. Additional background informationon the application of spline couplings and their inherent limitations may beobtained from references 3 through 7.

3. Figure 1 illustrates a typical example of spline wear as experienced with anaircraft hydraulic pump. For comparison purposes, the illustration also shows one ofthe new series of spline couplings which have demonstrated an immunity tofretting. The new couplings require no lubrication or periodic cleaning and aretolerant of the degree of misalignment experienced in aircraft accessoryinstallations. Figure 2 presents generally %,ccepted laboratory data, taken fromreference 6, which typifies the wear behavior of grease lubricated involute splinecouplings at various levels of misalignment. In contrastt figure 3 illustrates thebenefit offered by one type of nonmetallic spline coupling. These data, taken fromreference 8, when compared with figure Z, illustrate the degree of wear reductionprovided by the new nonmetallic spline coupling technique. Examination offigures Z and 3 at an acceptable wear limit of 0.01Z in. (0.30 mm), for a commonmisalignment level of 0.34 (leg, demonstrates that the nonmetallic spline couplingwill last 56 times as lone (1,400 hr versus 25 hr) as the standard grease lubricatedspline coupling. These typical laboratory test data have been verified by more than

68,000 hr of actual flight operations on 10 different drive shaft nonmetalliccoupling designs. During these flight tests, no coupling failures have occurred, noperiodic maintenance was required, and, in all cases, wear of the nonmetallicelements was negligible. Wear of the steel components was nonexistent.

TM 79-1 SY

MS14184 (AS) INVOLUTECOUPLING COUPLING

SPLINE WEARSPLINE WEAR

M$14184 (AS) SPLINE ADAPE

Figure 1Aircraft Hydraulic Pump and Shaft Coupling HardwareI Illustrating Typically Worn Standard Involute Splines and

The New Nonmetallic Spline Modification

TM 79-1 SY

0.26du0.34 dug

0.012 • '-

W" 0.17 d"

w 0.008z

-J

0.004 - - -.... - •

0 -' ,

10 100 1000-

METRIC CONVERSION HOURS OF OPERATIONI In - 25.4 mm

Figure 2Laboratory Induced Spline Wear of Grease Lubricated Splines

Showing the Effect of Spline Coupling Misalignment

j ~ ~~~~~0.016- --- ------0.012

i •iz 0.008

00

10 50 100 1low

METRIC CONVERSION HOURS OF OPERATIONMIC I On ERA ON (0.34 dhi" MISALIGNMENT)Itin - 25.4 mm

Figure 3

Laboratory Induced Spline Wear of Unlubricated, Internally andExternally Involute-Splined, Poiyimide Plastic Bushing Showing the

Reduction in Wear Rate

3

TM 79-1 SY

PURPOSE

4. This report presents a summary of the new nonmetallic spline coupling designapplications, contains previously unpublished test data, and includes the currentMilitary Standard Drawings.

SUMMARY OF SPLINE COUPLING APPLICATIONS

5. Twenty-two separate designs have been produced for evaluation during thecourse of this nonmetallic shaft coupling program. These designs can becategorized as MS14169(AS) circular splines, MS14184(AS) flat sided splines, andinvolute splines. Table 1 contains information on each of the Z2 applications whichhave been or are being evaluated during laboratory or flight operations. Thesedesigns are required to transmit torques from 27 in.-lb (3 N-m) to greater than6,000 in.-lb (565 N-m) and operate at speeds up to 26,000 RPM.

EXTERNAL SPLINE ADAPTER CONFIGURATIONS

6. In all cases, the nonmetallic adapters have been designed to be a tight fit inthe accessory or gearbox splined cavity. This tight fit, which serves a dual purposeof retaining the adapter and applying a compressive prestress, has been achieved byincorporating oversized flat sided splines on the outside of the adapter. Twodifferent methods of obtaining this fit have been used and are illustrated infigure 4. The primary difference between the two methods, side fit with rootclearance and saw slots and side fit with no root -clearance, reflects the need tolimit installation forces on the larger diameter adapters. Consequently, the sawslots were added and the root clearance increased in the MS14169(AS) design tolimit the axial force necessary to press the adapter into its mating splined cavity.The external spline geometry of the smaller MS14184(AS) adapters has beencarefully selected to limit the axial installation force.

4,

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TM 79-1 SY

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TM 79-1 SY

INTERFERENCE COLLAPSES SLOTI GENEROUS ROOT CLEARANCE

MS14169 (AS) ADAPTER

SIDE INTERFERENCE FIT

NEGLIGIBLE ROOT CLEARANCE

MS 14184 (AS) ADAPTER

Figure 4A Comparison of Two Types of Nonmetallic Shaft Couplings

Noting the rwo Preferred Methods of Achieving Rletention andCompressive Preload

TM 79-1 SY

INTERNAL SPLINE ADAPTER CONFIGURATIONS

7. The internal splines are circular in cross section for all generators, constantspeed drives (CSD's), and most starters. However, the proposed F/A-18 starternonmetallic coupling design will use an involute spline profile since, in this case,the torque capacity is considered of greater importance than misalignmentcapability. Some additional involute designs have been produced for applications inwhich compatibility with existing hardware and tooling is the major concern. Thehydraulic pump coupling designs have used the flat sided internal spline design inaccordance with MS14184(AS). In most cases, this profile has a greater torquecapacity than the closest standard involute design. Finally, because of the widevariety of fuel pump spline sizes, circular splines, as well as involute splines, havebeen proposed for fuel pump applications.

TACHOMETER GENERATOR SQUARE DRIVE SHAFT

8. One notable exception to the spline coupling configurations described above isincluded in the summary presented in table 1, The ZCM9ACF tachometer tests,which are applicable to all T-56 engine installations, have been conducted on shaftsbuilt in accordance with figure 5. In the strictest sense, this shaft coupling is not asplined coupling. Furthermore, the nonmetallic bushing used here is designed to fitloosely into the matching gearbox shaft cavity and is bonded to the tachometershaft using an epoxy adhesive. However, since it is a type of nonmetallic coupling,it is included in the summary for completeness. Three different couplingconfigurations have been used in the T-56 engine driven tachometer generatog

steel shaft, steel shaft with NYLON ) bushing, and steel shaft with VESPEL6bushing. The latter two designs are being compared in flight tests in the EC-130

aircraft to determine if the additional VESPEL® strength will eliminate the

observed tendency of the NYLON® to coI flow and ultimately fail. Prior flight

experience demonstrated that the NYLON bushing prevents the fretting wear ofthe square drive and mating gearbox shaft cavity experienced with the original allsteel shaft coupling.

I

TM 79-1 SY A7,

-:

NONMETALLIC SQUAREDRIVE BUSHING

ITACHOMETER GENERATOR

0,010" R MAX, (TYP)

0.147"0,145

J ..0,24 5" ,1Y

S" 0.243 0.599

NOTES:1, MATERIAL VESPEL SP,1 METRIC CONVERSION2, BUSHING ATTACHED WITH ECCOBOND 104 EPOXY ADH1ESIVE

CURED FOR 6 HOURS AT 2500 F. I In 25.4 mm

Figure 5Engine Driven Tachometer-Gencrator Illustrating the

Nonmetallic Square Drive Bushing Installation

- a

. ... . . . ......-- ~ *- ~ . I

TM 79-1 SY

SUMMARY OF RECENT TEST RESULTS

9. The evaluation of the ZZ separ.1te designs generally has led to or will result inseparate NAVAIRTESTCEN Reports of Test Results giving the details of eachdgesign test program. References 9 to 17 present the specific results from some ofthese coupling test programs. The information presented below is contained hereinbecause It is of general interest, illustrative of the nonmetallic coupling capability,and, in some cases, is previously unpublished.

CH-53E HYDRAULIC PUMP FATIGUE TEST

10. Figure 6 shows a test setup used to subject drive shafts to large numbers ofcyclic torque loads. The apparatus consists of an aircraft electrical starter whichdrives the test specimen through a torque transducer. One end of the test shaft islocked so that it cannot rotate. The other end of the test sample is twisted in acontrolled torque application produced by onergizing the electrical starter from aregulated current source. Candidate design shafts and nonmetallic adapters aresubjected to repeated load cycles in this apparatus to determine their torsionalfatigue strength. In the case of the CH-53E hydraulic pump drive shafts, variousconfigurations of nonmetallic coupling shafts and adapters were fatigue tested toachieve the maximun strength possible in a 0.6875 in. (17.5 mm) pitch diameter(P.D.) application. A sample trace of load cycles applied to prototype CH-53Ehydraulic pump drive shafts is shown in figure 7. The torque peak of 85 ft-lb(11.5 N-m) is followed by a damped oscillation caused by the release of storedenergy in the twisted shaft when the starter electrical current is interrupted. Thesrlected CII-53E shaft design was subjected to 30,000 such torque applicationcycles (not counting the negative torque peaks or damped oscillations) withoutfailure, The CH-53E pump spline test coupling is illustrated in figure 8 andconforins to the requirements of MS14184(AS).

I9

TM 79-1 SY

AIRCRAFT STARTER ADAPTER FIXTURE TOROUE TRANSDUCER

7-D

1r

T1 SAMPLE(SIIArT ANO NONMETALLIC SPLINE ADAPTER

Figure 6Shaft Torsional Fatigue Test Apparatus Using anAircraft Electrical Starter as the Prime Mover

10

TM 79-1 SY

0 -

60~f~~ ti.

Cu~ru mM Tm IE D,'fjn)[j1

Cr

If PE 1r I4*1

METRIC CONVERSIONI ft-fb =1,356 Nm

Figure 7Typical Torsional Load Cycles Applied to Test Shaft

Couplings During Shaft Torsional Fatigue Evaluaitions

TMt 79-1 SY

SPLINE ADAPTER DRIVE SHAFT SLN DPE

W71

1'S

/! 0.800 in. P.D. MS10.4184(5.067 n.PD

0.525 in. DIAMETE "*8TOH0.520

-I METRIC CONVERSION

I in. = ?.5.4 mm

Figure 8Proposed Aircraft Hydraulic Pump Nonmetallic

Shaft Couplings as Tested for the CII-53E

CI-53E HYDRAULIC PUMP SHAFT ENDURANCE TEST

11. Following successful completion of the shaft fatigue test, the proposedCII-53E hydraulic pump was equipped with a second identical shaft test sample.The pump was installed in the test configuration shown in figure 9, and thehydraulic circuit was connected in accordance with figure 10. During 400 hr ofoperation, the pump was automatically loaded and unloaded in a simulation of thee1xpected CII-53E operating scenario. Pump loads were varied throughout the test

at a rate of 3 Hz since the aircraft automatic flighit control servo system isexpected to vary its demand at that average rate. Figure 11 shows the actualrecorded load profile. i addition to the profile shown, the pump was stopped andrestarted (accelerated to 3700 RPM) 100 times to sinmlate the interval betweenflights. In figure 12, the recording speed was increased so that individual loadcycles could be defined. Drive shaft torque can be observed to vary from 15 to36 ft-lb (20 to 49 N-m) during the "normal" servo load condition of 4 to 11 GPM(0.2 to 0.7 I/s). During startup, the pump drive shaft torque increased to a peak of66 ft-lb (89.5 N-i) at which point the automatic pump piston stroke control

12

TM 79-1 SY

reduced the torque load to the 15 to 36 ft-lb (20 to 49 N-m) range. A sample starttrace showing this condition is presented as figure 13. At the end of the 400 hr test,the shaft was removed, visually inspected, and magnafluxed. The appearance of theshaft had not changed and no cracks were found. The adapters showed very littledeformation, no apparent wear, and had a polished appearance in the shaft bores.The 0.6875 in. (17.5 mm) P.D. pump spline adapter had cracked longitudinally atthree of the thin sections between the external teeth as shown in figure 14. Cracksof this nature do not significantly affect the strength or wear life of the adaptersince the adapter is restrained by the enveloping outer shaft spline. An attempt wasmade to break the shaft to check the shear section, but the internal teeth of the0.6875 in. (17.5 mm) P.D. adapter failed at 183 ft-lb (248 N-m). A second attemptwas made using a 0.800 in. (20.3 mm) P.D. adapter at each end of the shaft. Thisadapter with its slightly longer internal splines failed at 201 ft-lb (272 N-m). Noattempt was made to break the shaft without the adapters because it was felt thatuniform loading on the shaft teeth could not be obtained by other meant It shouldbe noted that during the 400 hr test, the shaft was subjected to 4.3 X 10 torsionalload cycles.

13

- -

TMl 79-1 SYI

C0

P-P

IxI

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14l

TM 79-1 SY

26 ga9nn 11mi golminn 4 gal/nn

I RESERVOIR

~I31I~- ----- PROPOSED CH.53E HYDRAUC PUMP

PROTOTYPE MS14184 (AS)0.526/0.520 In 0.0. SPUINED SHAFT

METRIC CONVERSIONSI n *25.4 mm1 psi 6.8948 ki'sI gal/min 6.308SX102 U/s

CH-5E Hdrauic ump Figure 10

CH-3E ydaulc PmpEndurance Test Diagram Showing thcRelationship of the Various Hydraulic Components

15

TM 79-1 SY

7-~UM INPU TORQUE !

ni~ titill

OPERATINPU PRUE60 Tin It lI~~~ 1~~,. ,

g.I! 2500 i

CASERSAVNG PLOWUR

Figur 111 "T 7

CH 53 yrui upEdrneTs eoddLa rfl

S4wn the CylcVraioNfteTstPrmtr PUMP UTPU FL[

1[I016 5 miIl I i I[it 1 111 il 11I1

TM 79-1 Sy

4i1

0

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7~i 0 ,iw

171

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Pit ~f - ~

-lit . 44, J-1-4

+

t~Lqw71-6

17

TM 79-1 SY

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TM 79-1 SY

NOTE: The axial cracks do not significantly affect the strength or wear rate of theadapter siu:f- tile adapter is restrained by the enveloping outer shaft.

Figure 140.6875 in. (17.5 mm) Pitch Diameter Spline Adapter Removed from the

Enveloping Outer Shaft Spline Following 4.3 Million Torsional Load Cycles

HYDRAULIC PUMP ACOUSTIC TEST

IZ. During the course of testing the CHI-53E pump drive shaft, various technicianscommented that the pump ran audibly quieter with tile nonmetallic coupling thanwith the standard steel drive shaft coupling. Consequently, at the end of tileendurance test, acoustic measurements were made using a tripod mounted, noiseintensity meter as shown in figure 15. These measurements were taken after all

other rotating or noise producing equipment (except for tihe puimp drive stand) w\asshut down to minimize the background noise. Furthermore, tile noise data were

recorded with the pump driven through the steel shaft and also through thenonmetallic coupling configurations twice to verify that the acoustic signaturtwere repeatable. Figure 16 gives the results of this test. The acousticmeasurements were significantly lower when the pump was driven by thenonmetallic coupling. The most noticeable noise reduction of 9 dB occurred at500 llz. which is in the frequency range of normal conversation. The frequency oftile peak noise level corresponds to the frequency generated by the product of thenine pistons and tile rotational rate of 62 I1z (3,720 RPM). Torque measurements

19j

TM 79-1 SY

shown in figure 17 were also taken with the standard steel shaft and with the

nonmetallic coupling. A comparison of the torque measurements at four differentpump test conditions indicates that the nonmetallic adapter dampens the inherentpump torsional oscillations and may in turn dampen the pressure pulsationsgenerated by each piston. This damping is suspected as the cause of the noisereduction.

PLAN VIEW MICROPHONEGENERAL RADIO COMPANYMODEL NO. 1933PRECISION SOUND LEVELMETER AND ANALYZER

HYDRAULIC PUMP

DRIVESTAND5"

- 18"

SIDE VIEW

METRIC CONVERSION 36" 4I in = 25.4 mm

Figure 15Location of the Acoustic Measurement Equipment with Respect to the

CH-53E Hydraulic Pump and Drive Stand

20' ZO 5

TM 79-1 SY

rr

c"

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71"I xco

cin

two !

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TM 79-1 SY

AIR TURBINE STARTER TESTS

13. Recent test of air turbine starters equipped with MS14169(AS) circular splineshave demonstrated the design's resistance to low cycle fatigue. The T-56 engine airturbine starter listed in table I as the P-3, A-24 starter was subjected to 1200, 61ft-lb (82.7 N-m) engine start cycles during laboratory tests at the Naval AirPropulsion Center (NAVAIRPROPCEN), Trenton. Following the start cycles, thestarter was motored at 14,000 RPM for 1,000 hr to simulate the over-runningcondition experienced during flight. The nonmetallic coupling was in excellentconditions at the end of the test, exhibiting a minor amount of wear/deformation asshown in figure 18.

WEAR DEBRIS ACCUMULATEDIN SPLINE ADAPTER

STARI UR DRIVE SHAFT

Figure 18T-56 Engine Air Turbine Starter Nonmetallic Coupling ComponentsFollowing 1Z00 Start Cycles and 1000 Hr Continuous Operation at

14,000 RPM

23

TM 79-1 SY

14[. A similar test of the F-14, A-28 air turbine starter with an equivalent circularspline was less successful. The F-I'4 starter was subjected to 1200, 450 ft-lb(610 N-rn) engine start cycles at NAVAIRPROPCEN. The nonmetallic couplingexhibited no cracks and minimal deformation when examined after 497 starts.However, when examined after 1200 start cycles, the nonmetallic adapter showedsevere deformation with cracks underlying the internal teeth. The condition of thisadapter is shown in figure 19 (taken following the 1200 start cycles). The results ofthe F-14 air turbine starter nonmetallic spline modification indicate the upperlimit for the basic size 1 circular spline. It should be noted that the static torsionallimit for the size I circular spline adapter was previously determined to be567 ft-lb (768 N-tn). In this light, the results of the starter endurance test areencouraging. These tests will be resumed with a nonmetallic adapter made from astronger polymeric plastic material.

CRACK UNDERINTERNAL SPLINE

SEVERE PLASTICDEFORMATION

Figure 19Nonmetallic Adapter Damaged During 1200 Cycles of theF-14 Engine Air Turbine Starter

24

TM 79-1 SY

ADDITIONAL NONMETALLIC SPLINE ADAPTER DATA

15. Ultimate torsional strength data are being compiled for various sizes andcombinations of the MS14169(AS), MS14184(AS), and certain special nonmetallicadapters. Table II presents the available data for the configurations which havebeen tested. The listed ultimate torsional strengths result from measurements ofthe static torsional stress which causes failure of the nonmetallic adapter at roomtemperature. In some cases, the failure is characterized by fracturing at the baseof the internal spline teeth. In other cases, the failure exhibits the appearance ofexcessive slip and compressive deformation. Figure 20 illustrates these two typesof adapter failure. In general, the type of failure appears to be due to the way thetorque load is transposed- to shear and compressive stresses by the spline geometryof the nonmetallic part. Figure Z shows that the torque load results in substantialshear stress in the circular spline, whereas the compressive stress predominates in

4 the flat sided or involute shaped splines. Consequently, in the circular spline,slippage and compressive deformation should predominate, whereas fracture of theinternal splines should predominate in the flat sided and involute teeth. Figure 21also contains various design parameters which indicate the relative merits of thethree different spline shapes. The product of the number of teeth (N) times thearea per unit length (A) gives the total spline load bearing area (N-A). This areahas been maximized in the MS14184(AS) flat-sided splines at the expense of thesteel inner shaft strength. The reduction in the steel inner shaft strength is due tothe relatively deep root diameter of the flat-sided splines. Thes analysis indicates:

a. MS14169(AS) circular splines should be used for moderate torque loadapplications in which misalignment due to tolerance stackup, overhungmoment, and flight dynamics is probable.

b. MS14184(AS) flat-sides splines should be chosen when per-unit-area loadmust be minimized to limit wear due to high frequency cyclic loads, whenmisalignment is not severe, and when the relatively weaker inner shaft willprovide an adequate safety margin.

c. Involute splines with nonmetallic adapters should be used when the steel

inner shaft is severely limited in diameter relative to the transmittedtorque load making use of the circular or flat-sided splines impractical.

25125

TM 79-1 SY

Table H

Ultimate Static Torque Load for Various NonmetailicAdapter Configurations (Room Temperature Performance,

Values in ft-lb)

Sample Length (in.)

Test Sample Type(VESPEL SP-1 Material) .375 Other

MS14169 (AS)Size 3/4 68-7ZSize 1 205 (CALC) 137 (.250)

MS14184(AS)

Outside InsidepD( I) D~)P T

( 3 ) FD (4 )

.6000 Z0/40 6 .450 84

.6875 16/3Z 6 .450 75-81

.6875 16/32 8 .525 108-109

.8000 20/30 8 .5Z5 111 183 (.700)

.8000 20/40 8 .525 109-113 ZO (.800)

.8000 ZO/40 8 .615

SPECIAL

Outside Inside

MS14169 Size 3/4 8T .5Z5 FD MS14184 94-98 211 (.750)

MS14169 Size 3/4 8T .615 FD MS14184 124

MS14169 Size 1 MS14169 Size 3/4 62

MS14169 Size I 16T .800 PD 20/30 INVOL 190 (CALC) IZ7 (.Z50)

lIT .4583 PD lIT .Z75 PD 40/80 INVOL ZZ (CALC) 19 (.325)

ZIT .8750 PD 6T .450 FD MS14184 64ZIT .8750 PD 8T .615 FD MS14184 125

MS14184 .8000 20/30 MS14169 Size 3/4 79

NOTES: (1) PD indicates Pitch Diameter in inches.(2) DP indicates Diametral Pitch.(3) T indicates the Number of Teeth.(4) FD indicates the Form Diameter in inches.

Z6 m m1

Th 79-1 SY

FAILURE MODE SLIP/ r,'COMPRESSIVE DEFORMATION

FAILURE MODE- FRACTURE

Figure ZOC¢otnIarison of the Tw'o Tl'ypical Nonmetallic Adaptor Failure Modes:

Slip/Compressive Deformation Associated with the Circular Splines andFracture Associated with the Flat-sided Splines

Z 7.. ... .. .. .. .... ........ ........,.,, ., , ,

TM 79-1 SY

-i o 0Q

as~a

cc .

wl %:4

t)..

288

TM 79-1 SY

MILITARY STANDARD DRAWINGS

16. MS14169(AS) gives the recommended circular spline coupling geometry andmanufacturing tolerances for three basic sizes which replace the 0.800 in.(20.3 mm) 16 tooth, 1.200 in. (30.5 mm) 24 tooth, and 1.625 in. (41.3 mm) Z6 toothinvolute spline couplings. MS14184(AS) contains similar data describing sixdifferent flat-sided spline coupling combinations which replace the 0.600 in.(15.2 mm) 1Z tooth, 0.6875 in. (17.5 mm) 11 tooth, and 0.800 in. (20.3 mm) 16 toothinvolute spline couplings. Appendix A contains copies of the latest issue of each ofthese Military Standard Drawings. Tne special involute splined nonmetallic adaptersreferred to previously were designed using standard involute spline data taken fromAS84B and AS972, published by the Society of Automojive Engineers, Incorporated.

29

TM 79-1 SY

CONCLUSIONS

17. Actual flight operations totaling 68,000 hr on 10 different drive shaftnonmetallic coupling designs have verified the value of this new technology.

18. Hydraulic pump endurance testing indicates that properly applied nonmetallicadapters can endure millions of stress cycles.

19. Air turbine starter tests have established that the low cycle fatigue limit forthe circular spline design approaches the static torsional limit of the nonmetallicadapter.

Z0. Wear of the metal or plastic coupling parts is negligible even when the loadapproaches the torsional limit of the nonmetallic adapter.

Z2. Preliminary acoustic tests performed on a hydraulic pump equipped with anonmetallic spline coupling determined a 9 dB reduction in the predominant audiblefrequency.

PLANS

22. New applications will continue to be examined during laboratory and flighttests.

Z3. Future programs will emphasize the establishment of nonmetallic couplingperformance standards, preparation of a nonmetallic adapter military specification,and the qualification of alternate nonmetallic materials.

30

,r i ,,,Ii

TM 79-1 SY

REFERENCES

1. Aircraft Engine Driven Accessory Shaft Improvements Using High-Strength,Low Wear Polyimide Plastic, Technical Memorandum TM 76-1 SY,30 December 1976, by Aleck Loker, Naval Air Test Center, Patuxent River,Maryland.

2. Aircraft Engine Driven Accessory Shaft Coupling Improvements Using High-Strength Nonmetallic Adapter/Bushings, A Progress Report, TechnicalMemorandum TM 78-1 SY, 31 March 1978, by Aleck Loker, Naval Air TestCenter, Patuxent River, Maryland.

3. Machinery's Handbook, 19th Edition, 1974, Industrial Press, Incorporated, 200Madison Avenue, New York, New York.

4. Aircraft Spline Reliability Predictive Technique Development and DesignMethodology, Second Progress Report, 1 February 1975 to 30 June 1975, byDimitri B. Kececioglu, et.al., University of Arizona, Tuscon, Arizona.

5. Fretting, SAE Aeronautical Information Report No. 47, 15 December 1956,Society of Automotive Engineers Incorporated, New York, New York.

6. Spline Wear Effects of Design and Lubrication, Paper No. 74-DET-84 October1974, for the American Society of Mechanical Engineers, by P. M. Ku and M.L. Valtierra, Southwest Research Institute, San Antonio, Texas.

7. A Critical Survey and Analysis of Aircraft Spline Failures, Final Report,18 August 1971, by M. L. Valtierra, R. D. Brown, and P. M. Ku, Southwest AResearch Institute, San Antonio, Texas.

8. Mitigation of Wear of Interface Splines, Preprint No. 77-LC-6B-1, October1977, for the American Society of Lubrication Engineers, by M. L. Valtierraand P. M. Ku, Southwest Research Institute, San Antonio, Texas.

9. Development of a Circular Spline Shaft Coupling for the 30AGDO3 CSD/J79Engine Transfer Gearbox Interface, Final Engineering Report, December 1973,by R. Coss and H. Brown, ARINC Research Corporation, Annapolis, Maryland.

10. Evaluation of the ARINC Circular Spline Coupling for the F-4 Engine TransferGearbox/ Sun ds trand Constant Speed Drive Interface ,' Final Report No.SY-16R-76, 30 January 1976, by J. T. Meredith, Naval Air Test Center,

Patuxent River, Maryland.

11. Development of a Circular Spline Coupling for the 28B95 Generator/T-56Engine Gearbox Interface, Final Engineering Report, December 1973, by R.Cross and H. Brown, ARINC Research Corporation, Annapolis, Maryland.

12. Evaluation of the ARING Circular Spline Coupling for the P-3 EngineAccessory Pad Gearbox/Bendix 28B95 Generator Interface, Final Report No.SY-?2R76, 30 January 1976, by J. T. Meredith, Naval Air Test Center,Patuxent River, Maryland.

31

m r N ll

TM 79-1 SY

13. Test on VESPEL® Bushing with ARINC Shaft on 28B95 AC Generator, TestReport No. E30Z385, 17 June 1974, the Bendix Corporation, Eatontown, NewJersey.

14. Evaluation of the ARINC Circular Spline for the Bendix 28B139 GeneratorInput Shaft, Final Report No. WST-17R-75, 17 March 1975, by J. T. Meredith,Naval Air Test Center, Patuxent River, Maryland.

15. Evaluation of the Circular Spline Coupling for EC-130Q Aircraft 40/50 KVGenerators, Interim Report No. SY-164R-76, Z4 August 1976, by J. Bortzfield,Naval Air Test Center, Patuxent River, Maryland.

16. Development of an Improved 0.600 in. (15.2 mm) Pitch Diameter Splined ShaftCoupling, Final Report No. SY-174R-77, 13 September 1977, by J. T.Meredith, Naval Air Test Center, Patuxent River, Maryland.

17. Fleet Field Evaluation of Improved 0.600 in. (15.2 mm) Pitch DiameterCoupling for H-53 First Stage Hydraulic Pump,Final Report No. SY-24R-78, byJ. Hall Naval Air Test Center, Patuxent River, Maryland.

3Z

TM 79-I SY

NONMFTALLIC SPLINE COUPLING MILITARY STANDARD DRAWINGS

MS14184(AS)NONMETALLIC SHAFT-COUPLING DETAILSENGINE DRIVEN ACCESSORIES

8 SEPTEMBER 1978

MS14169(AS), REVISION BCIRCULAR SPLINE AND ADAPTER DETAILSENGINE DRIVEN ACCESSORIES

22 FEBRUARY 1978

33 APPENDIX A i [

TM 79-1 SY

6115 .

F SEE NOTE BELOW

0/0i -_ 6 FLAT SIDED TEETH

0.03 x , ° CHAMER -EQUALLY SPACED WITHIN0.500 OF TRUE POSITION

1055' 905,E 1045' -N

/

7E 00

_______ D DETIL

DETAIL A DETAIL A

6 TEETH 8 TEETH

SPLIHE DESIGN DATA

OHOI OVEP 2 LHGAGM'T0AJ ROOT ROOT WIRES WIRE 1.!14TH

TEETH DIA. DIA. WIDTH DIA DIA MIH.A B C D E F

0.450 0.6953 0.1920 0.700

I 45 0.6928

0.525 0.405 0.067 0.7 1.1800 0.7000.520 0.395 0.7675 0

0.615 0 455 063 0.8230 0.80 0.750.610 0445 0 0.3205

SINAV " -AS TITLE MILITARY STANDARDs CrA Mw c s t :ONET,\LLIC S HALFT- CO PL IG DETAILS .,EHI O , OMS14184(AS)

F.1 PCU~j'tt ENCIFICATIGll sII*ucsE VIEET OF~ 3

DDb .2,672-1 fLj.*..,. .. ) P RHOJECT NO. 6115-H423 ftATI 6O 3NII

NOTE: GISAN ERROR.AMENDED DRAWING WILLIDENTIFY LENGTH AS F.

34 APPENDIX A

TM 79-1 Sy

-p/

* ~S*. UP ClAS

R N

-,0 013 - ' - 0

-. 'a VN- ~ b.C 0 _ _s

MMALI K,-OVI /t~ls RRT SADR"GIN't ~ ~ ~ DR 0I VI0CUOM'"'M III

14 !8(S

1 FO

3 5I APPENDIXAS

TM 79-1 SY

PI P CLA,,

6115

REQUIREMENTS

1. SPLINES. HALE SHAFT SPLINES SHALL HAVE A HINIHEII SURFACE HARDNESS Or 3, ROCkELL CThOIANIHUM CASE DEPTH or 0.035 INCHES

2. MATERIAL SELECTION. THE PLASTIC SPLINED BLSHING SHALL BE FABRICATED FROM hIGH STRENGTH,~U' Tr .TlPOL'hE R C HATERIALS HIVING ILTIATE COMPRESSIVE STRENGTHS Or A HNINUIMIUOF 28.000 PSI. TYPICAL 14ATERIALS INCLUDE THE POLYIIDE. ARA.MID AND POLYAMIIDE-INIDERESINS. BELONGING TO "IVE DUPONT VESPEL AND A4OCO TORLON FAMILIES, THE PROCES$ OfHATERIAL SELECTION SHOULD CONSIDER STRENGTH. FATIGUE AND AGING PROPERTIES. FLUIDCOMFATIBILITY. THERMAL EXPOSmRE, DIHENSIONAL STABILITY. AND FOP-XING PROPERTIES

3. SHEAR SECTION THE SHAFT SHALL INCLUDE A SHEAR SECTION ALLOWING THE SHAFT TO SHEAR ATTR R'-t-"LCIIED By THE SPECIFICATION FOR THE ACCESSORY EQUIPMENT

NOTES

1. DIE.NSIONS ALL LINEAR DIMENSIONS ARE IN INCHES EXCEPT ROC.GHNESSES WHICH ARE INPRISCRts

2. APPLICATION THE SPECIFIED BUSHINGS MAY BE USED ONLY WITh INVOLUTE SPLINES HAVING 30DTXT"T SURE ANGLES

3 FINISH ALL BURP$ AND SHARP EDGES SHALL BE REM.OVED

4. APPLICATION AND INSTALLATION THIS COL'PLING IS DESIGNED TO BE USED AT THE INTERFACE orET-R 't \'"r'fl-t} Ou-'PT SHAFT OF "HE AIRCRAFT ENGINE DRIVE PAD VITHOLT

HODIFICATION OR REFLACEVENT OF THE EXISTING FE.'ALE OUTPUT SHAFT THE FE.ALE SHAFT SPLINESHALL BE THROUGHLY CLEANED TO REMOVE SEDI.ENT AND GREASE BEFORE INSTALLATION OF THE BUSHINGTHE DESIGN RESULTS IN AN INTERFERENCE FIT OF THE BUSHING INTO THE INVOLUTE SPLINE AND ASLIDING FIT OF THE NEW ACCESSORY SHAFT INTO THE. BUSHING.

! -4

[j

I °3w,)

IA, NAV,, -ASLI PAIL.coTARY STAND'.

I~i1A E~NE RIVEN. ACCESS(ORE M S14184 (A S)

.i

36 APPENDIX A

TM 79-1 SY

ID SUP cLASSiSI 1.

METRIC CONVERSION

1.00 in. - 25.4 mm

F 12 N A2TIR

SECTION A-A

:0

j-4

CIRCULAR SPLINE r;

S'LINE DESIGN DATA L

ROOT SHAFT SHAFT TOOTH c.1BASIC NO OFI SPLINI FORIF DIA TOOTH CROWN SPI.INE DIA LENGTH INDEXSIZE IlLTH' DIA DIA PAX RADIUS RADIUS LENGTH MAX PIN ANGLE

A _ C D F r G H J

0 bOO 0 - 0 47 0 091 100 08s0 8 ASIC 0 410 0 091 8 0 0 63 0 418 0 31 60

°

I B 000 0 7.O8 l998 BASIC 0 S00 0 1242 1' 0 ' 10 0bO 04 5"- 1 3 0 0 90 0 610 0 41, 43o

. 6 o 230 0 93 I 000 0 13 1 10 35B 248 IASIC 1 0 133 14 0 I 910

* U

M S

othe : us C \\IRCULAR SP INEL D APE D' 'I(II.AIIS 'KIl L

- 3 I oI-

37 APPENDIX A

3 4

TM 79-1 SY

0000c; 00N;

Lb EO

-' -

900

060

U.5 00 00

pJ A DV -AS VI.I

rKJ\ NE ,y VE AC N N x

foolo a#c two *ot-o

38 APPE00I00

TM 79-1 SY

F to. up CLASS1

NOWE

lierdial-nlions are in inches except toughnieses wihich are In miron,hes.

Th pcte adapter% ma, be used only with involute spline% having lt Jclyree %

It lure antilr$.

10 XS aft splInchO shall have A miIMa. %kiirfd, h~mmdse%% of 34 Rockuell I. to a mltom.,caqe depth of O.0S kihes.

Alumr' and sharp edge, hall he removed.

?T~uirspinesopiinsaa~he used a% telimement% for worn involut sitesoll lgwithout modification or replacescint of the aircraft .msesnot) drive ad shaft Tiemalv%pflne). prior to retrofit, the female srilIne %hill he thoroughly leaned to iamo~v,ediment and grease. The design results in an interference fit of the %Cline adapltrinto the involute spline a nd a %tllding fit of the circular spline shaft init the a~itk-1

Tr ~tRkLLTn adaipter %haill he fahricatril from high ntrength. .v'ii-lultrivjtttpolari~mc materin~ having ultimavte %omprvAive strvngths of a wiii.,,. of 211.111111 1-11Tyicaul miterials include the lpolimidv. aramid and pol T &aide- im~e rv'suns, heloiogiligt6 the Puspont Vespel and Amoco lotion ramiles. 1he lirocns of material seivleatoushould consider strength, fatigue and aging lproiverties,. fTld compatibility, the-immeiosure. dimensmon~i %tahility, aod forming preperties.

'Tie'WN Zi'll include .i shcrin se, t on al louing The shalt to sheomr aln the to iq'.,sled fined h) the ';i,.ficit ion for the .mvtesory eiquipment.

ider the condttion- of paitent numbher '1.624i,i110. "ltielp'Pilot'. I1flnesamIianitj leicble Colplings"*. d.Ited Notenher Itb, JIM~l, ARIhI ileseirch lo'o~t on hi' viamiiisato the tlnmte~ %tate% tCovernpent aro.aity' free I icense to use the des, ibed sir, .1msplint coupling design for goveenmentai puirpose% only.

hi

Wi

P.A'NAV - A TI MILTAR STA DAROthe eve CICULA SPhT AAPTR DEAIL

MINEDRIVN A~tMIRS S 14 69 Afit(F~vX )-%1 TFMMW-I-V'Oftil )11T

D D."hat" 6 Z-1ikw.., ol"" tae""1-4"a" t QMTS

39 APEDI

TM 79-1 SY

* DISTRIBUTION:

NAVAIR (AIR-OOx)(1NAVAIR (AIR-Ol A)(1NAVAIR (PMA-Z31)(1NAVAIR (PMA-Z34)(1NAVAIR (PMA-Z35)(1NAVAIR (PMA-240)(1NAVAIR (PMA-Z44)(1NAVAIR (PMA-Z53)(1NAVAIR (PMA-Z55)(1NAVAIR (PMA-Z56)(1NAVAIR (PMA-Z57)(1NAVAIR (PMA-261)(1NAVAIR (PMA-265)(1NAVAIR (AIR-03)(1NAVAIR (AIR-330)(1NAVAIR (AIR-340)(1NAVAIR (AIR-04)(1NAVAIR (AIR-OS)(1NAVAIR (AIR-51O)(1NAVAIR (AIR-5ZO)(1NAVAIR (AIR-530)(1NAVAIR (AIR-536)(1NAVAIR (AIR-5364)(1NAVAIRTESTCEN (CTOZ)(1NAVAIRTESTOEN (CT84)(1NAVAIRTESTCEN (CTO8)(1NAVAIRTESTCEN (SY0l)(1NAVAIRTESTOEN (SYOZ)(1NAVAIRTESTCEN (SYO3)(1NAVAIRTrESTCEN (SYO4)(1NAVAIRTESTCEN (SY41)(1NAVAIRTESTCEN (SAO1)(1NAVAIRTESTCEN (RWOl)(1NAVAIRTESTCEN (AT0l)(1NAVAIRTESTCEN (TPO1)(1NAVAIRTESTCEN (TSO1)(1DDC (Z)

40 '