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250-CZOB CEB-10COMMERCIAL ENGINE BULLETIN overhaDetmit Diesel AllisonIndianapolis, Indiana 46206

PAGE 1 OF -December 12, 1

GOVERNOR, POWER TURBlXE, BENDM MOD:EL AL-AA1--MODIFICATION TO PART S LIST NUMBER 2524667 -2PLANNING INFORMATION:ZFFECTNITY:

XEASON:

All 250-C20B E mine Assemb lies prior to S/N CAE 830342,equipped with P N 6876568 Power Turbine Governors (BendixMode l AL-AAl, P/L No. 2524533-l) to be used on BolkowBO 105C and D and Agusta A109A helicopters.This mod ification provides power turbine governors withgreater reliability and service life for use on the DDA 250-C20engines to be installed in BO105C, BOl05D and A109 A helicopte

3ESCRIPTION: To provide m odification instructions for the following items:

TOMPLIANCE:

4PPROVAL:ClANPOWER :

l Ball Bearing governor weights replace the existinggovernor weights.l A larger diameter weight pin replaces the existingweight pin.l A drive shaft assembly with larger pin holes in thechanne l replaces the existing drive shaft assembly.l A higher rate spring replaces the existing governorspring.

It is recommended that this bulletin be accomp lished no laterthan next overhaul.FAA-DER approved.Approximately 2.0 additional manhours over the normal overhwill be required to accomplish this mod ification.

MATERlAL AVAILABILITY:New PartNo.253903325390342523240

Nomenclature Qt:i Availability-_Drive Shaft Assy 1 Rework P/N 25260Weight, Governor 2 Rework P/N 25238Bearing-Ba ll 4 Through BendixProduct Support Ce

Revision No. 2November 30 , 1976Rolls-Royce Proprietary Data Uncontrolled Printed Copy

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250-C20B CEB -1077OverhaulPage 2

COMMERCIAL ENGINE BULLETINGOVERNOR, POW ER TURBINE, BENDIX MODEL AL -AA1--MODIFICATION TO PAR TS LIST NUMBER 2524667-2

MATERIAL AVAILABILITY: (continued)New PartNo. Nomenclature Qty. Ava ilability2522102 Pin Straight 2 Through BendixProduct SupportCenters2529153 Spring, Governor 1 Through BendixProduct SupportCenters2537700-73 Bleed, P,-Pg 1 Through BendixProduct SupportCenters

TOOLING: NoneWEIGHT ANDBALANCE:REFERENCES:

NOT AFFECTED.CW-1526A and CW-1547Bendix G TSB No. 77250-C20B CEB-1081

PUBLICATIa SAFFECTED: Overhaul ManuaI and Illustrated Parts Catalog, Bendixform 15-571 dated 15 August 1973, Change I dated 16January 1974, Change II, dated 11July 1975.

Revision No. 1June 24, 1976Published December 12,1975

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250-CZOB CEB-1077OverhaulPage 3COMMERCIAL ENGINE BULLETIN

GOVERNOR, POWER TURBINE, BENDIX MODEL AL-AA 1-MODIFICATION TO PART S LIST NUMBER 2524667-2

ACCOMPLISHMENT INSTRUCTIONS:I. Utilizing the overhaul manual, Bend ix form 15-571, m odify the powerturbine governor as indicated:

From ToBendix BendixDDA P/N Parts List No. DDA P/N Parts List No.6876568 2524553-1 6891971 2524667-2A. Rework P/N 2526008 Drive Shaft Assemb ly to P/N 2539033 DriveShaft Assemb ly by drilling the pin holes in the channel to thedimensions given in Figure I.B. Rework P/N 2523862 Governor Weight to P/N 2539034 GovernorWeight by drilling the pin holes and removing material to thedimensions given in Figure 2.C. Install the P/N 2523240 Ball B earings into the P/N 2539034

Governor Weights.D. Assemble the P/N 2539034 Governor Weights with the ball bearingsinstalled to the P/N 2539033 Drive Shaft Asse:mbly using the P/N2522102 Pin to retain the weights in the channel.E. Replace P/N 2529242 Governor Spring with P/N 2529153 Spring.F. Replace P/N 2537700-70,P/N 2537700-71, -71, or -72 P,-Pg Blee d with-72. or -73, as required, for calibration.

II. Final Calibration Procedure and Limits. Calibrate the power turbinegovernor in accordance with Figure 3.III. Reidentify the mod ified power turbine governor by installing a new P/N2647428 Identification Plate with the following information either metalstamped, vibropeened, or scribed.

1. Model: AL-AA12. Allison SOCN: 6891971

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250-C20B CEB-1077OverhaulPage 4COMMERCIAL ENGINE BULLETIN

GOVERNOR, POWER TURBINE, BENDIX MODEL AL-AA1-MODIFICATION TO PARTS LIST NUMBER 2524667-2

3. Parts List: 2524667-24. Less Issues: Leave Blank5. Transfer the exact serial number from the old identification plate.

Iv. Record compliance with 250-C20B CEB-1077 in the Engine Assembly(white pages), Mod ification Record Part III of the Eng ine Log Book.

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250-C2OB CEB- 1077OverhaulPage 5

COMMERCIAL ENGINE BWLLETINGOVERNOR, POWER TURBLUE, BENDIX MODEL AL-Ah1-MODIFICATIOPi TO PARTS LIST KUh:B:ER 2524667-2

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250-CZOB CEB- 1077OverhaulPage 6

COMMERCIAL ENGINE BULLETINGOVERNOR, POWER TURBINE, BENDIX MODEL AL-AA1

-MODIFICATION TO PARTS LIST NUMBER 2524667-2

BOTH SIDES

BOTH SIDES 1THIS PLANE ESTABLISHED/BY C DIA AND TANGENCYPOINT OF 0.040-o. 050 R

0.0.3211

. 0.107o. lo5 BEFORE PLATING0.113-0. AFTER PLATING

0.010 MINIMUMWALL THICKNESS

GOVERNOR WEIGHT REWORKFIGURE 2

Revision No. 1June 24, 1076Published December 1

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250-C2OB CEB-1077OverhaulPage 9COMMERCIAL ENGINE BULLETIN

GOVERNOR, POW ER TURBINE, BENDlX MODEL AL-AA1-MODIFICATION TO P.4RTS LIST NUMBER 2524667-2

MATERIAL INFGRMATION:New P/N Qty Nomenclature Old P/N &ty6891971 Governor Assembly- 6876568 1(Bx 2524667-2) Power Turbine (Bx 2524553-l)2539252 1 Body Assy, Drive 2537928 1Complete2539033 1 Shaft Assy Drive 2526008 12539034 2 Weight, Governor 2523862 22522 102 2 Pin, Straight 2537524 2Permissible touse 343698 asan alternate to25375242523240 4 Bearings Ball e--m_- --------- -- Washer NonM etallic 343715 42529153 1 Spring, Governor 2529242 12539500 1 Cover Assy. 2537927 12537700-71, 1 Heed, Pr-Pg 2537700-70, 1-72, or -73 -71, or -72

2647428 1 Plate Identification 2647428 1186739 2 Screw, Self Tapping 186739 2Stock Dispos ition Notes:A Rework and reidentifyB ScrapC Added

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250-C20B CEti-1677OverhaulPage 10

COMMERCIAL ENGINE BULLETINGOVERNOR, PO WER TURBEYE, BENDIX mDEL AL-AA1

--MODIFICATION TO PAR TS LIST NUMBER 2524667-2MATERIAL INFORMATION (continued)D Scrap only removed P/N 2537700-70 Bleeds

L. 0. Davidson, Service ManagerGas Turbine EnginesMJK/rjk