CEB1053

7/29/2019 CEB1053

1/30

Aikion GAS TURBINE DIVISION

ENGINE MODEL 250-C2.0 SERIES--CON VERSION TO MOD!EL 250-CZOB

PLANNING INFORMATION:Effectivity:Model 250.C20 Series EnginesReason:To provide a Model 250 Series Engine with increased performance--400 to420 shaft hp.To increase performance and improve reliabil ity, the following majorfeatures were incorporated in the 250.CZOB design.

Turbine:0 First-stage Nozzle. Casting material changed from X-40 toMAR-M509 to increase the high temperature strength and lower

the coefficient of expansion. This change improves theresistance to erosion and cracks in the vames facilitatinglonger endurance life. Also, the nozzle-tie-diaphragm brazejoint is relocated toward the center of the inner band toreduce the bending stress of the new universal diaphragm.(Reference CEB-1048).

0 First-stage Wheel. The rim thickness is increased to reducethe tendency for cracks to originate in the rim. Also , theblades and rim OD feature Alpak Sl coating for sulfidationprotection coating. (Reference CEB-1048.)

0 Second-stage Nozzle. Material changed from X-40 to IN-738 toimprove (1) high temperature strength and (2) stability . loimprove interstage seal concentric ity, a ring was added toincrease seal stiffness. Also , the first-stage cooling airholes are parallel to the engine center line. A balance airannulus was added in the nozzle outer band to transfer highpressure air from within the gas producer support to the powerturbine support. (Reference CEB-1054.)

November 17, 1975 250.C20 CEB-1053Revision 3February 15, 1991 Page 1 of 30

Rolls-Royce Proprietary Data Uncontrolled Printed Copy

7/29/2019 CEB1053

2/30

ALLISON GAS TURBINECommercial Engine Bulletin

PLANNING INFORMATION: (Continued)0 Gas Producer and Power Turbine Supports. Material changed from14.4PH to IN-718 to (1) increase high temperature strength and

(2) improve stabi lity. This change affords improved alignmentof the main line bearings. Also , the external balance airtubes, which transfer high pressure air between the gasproducer and power turbine supports were eliminated.

0 Third-stage Nozzle. Flow area increased six percent forincreased hot day high altitude performance.0 Fourth-stage Nozz le. The nozzle features a new diaphragmhaving a C-shaped cross-section. A replaceable fine-pitch

corrosion resistant steel interstage seal is used in place ofthe nickel plated seal, thereby reducing performancedetermination. (Reference CEB-1045.)

Compressor0 New compressor front support with modified inlet guide vanes,first-stage wheel with reset blades, and second and third-stage

wheel assembly with second-stage blades reset are installed toincrease airflow for improved performance margins.0 The involute profile of the 17.tooth gear of the new spuradapter gearshaft and the mating 84.tooth gear of the new fuel

control and oil pump gearshaft in the gearbox are modifiedsligh tly for smoother operation, reducing noise and vibration.Since this change is released to the 250-C20 and C2OB on a 'usestock " basis, it is optional to replace the present gearshaftswith the new configuration. If the present gearshafts arerejected at overhaul, it is recommended that the new gearshaftsbe installed.

November 17, 1975Revision 3August 1, 1988

250-c20 CEB-1053Page 2 of 30


7/29/2019 CEB1053

3/30

250-C20 CEB-1053Page 3COMMERCIAL ENGINE BULLETIN

ENGINE, MODEL 250-C20 SERIES-CONVERSION TO MODEL 250-C20B

Gearboxl The breathing capacity of the gearbox is increased bproviding a gasifier train idler spur gearshaft withlarger diameter breather holes. The new gearshafthas also been released to all other Mode l 250 seriesengines on a use stock basis.0 A new and improved roller bearing, featuring crownrollers in lieu of cylindrica.1 rollers, is provided for

the forward pos ition of the ~power takeoff shaft.0 The involuteprofiles of the :following power tram geaare modified for smoother operation, reducing noiseand vibration: helical gear, torquemeter gear-shaft,and power take-off gearshaft.

Fuel Control SystemFue l system components and plumb ing hardware (e.tubing, accumulators, brackets, clamps, etc.) areidentical to the current 250-C20 Ben dix and CECOfuel control systems except for the Bend ix and CECfuel controls.To provide a slightly higher N1 speed at the go-degresetting, which is required by the 250-C20B engine,the CECO and Bend ix fuel control assemb lies aremodified in accordance with[ 250 CEB-1055 and CEB1056, respectively.The C20/C20B Bend ix and CECO control/governorinterchangeability is summarized in Table 2,


7/29/2019 CEB1053

4/30


ENGINE, MODEL 250-C20 SERIES- CONVERSION TO MODEL 250-C20B

DESCRIPTION: The Accomplishment Instructions of this bulletinare divided into two sections: I. Replacementand Rework and II. Reiden tification. In Section I,parts which must be replaced or reworked arealso illustrated. If rework is required, a separatebulletin is referenced.Section II details reidentification of major com-ponents and the engine assembly.

Table 2. 250-C20/C20B Bend ix and CECO Control/Governor Interchangeability

Unit6876568 Governor(Bx2524553-1)

Model250-C20 250-C20Bx X

6887766 Fuel Control(Bx2524552-4)6887755 Fuel Control(Bx2524644-1) x-x6886409 Governor(CECO 104100A8)6886410 Governor*(CECO 104500A3)

X X

X X6890904 Fuel Control(CECO 104000All)689289 5 Fuel Control(CECO 104900A4)6891454 Fuel Control(CECO 104000All-A106892896 Fuel Control(CECO 104900A4-A2)

* Multi-en ine Applications I** CEB-1055 p rovides a common CECO Fuel Control for the 250-C20FORM~41-1and C20B engines.Rolls-Royce Proprietary Data Uncontrolled Printed Copy

7/29/2019 CEB1053

5/30



lNTERCHANGEABlLITY:

COMPLIANCE:

APPROVAL: FAA-DER Approved.PREREQUISITES: This bulletin defines conve rsion of a specific configuratio250-C20 engine. The engine must incorporate the bullelisted in Tab le 3 to meet this configuration.

MANPOWER:

All changes described in this bulletin, including reworkdefined in reference bulletins, must be accomplishedsimultaneously.This bulletin may be accomp lished at the option of theoperator following no tification of FA A certification of250-C20B powered aircraft: operating with either fuelcontrol system. FAA certification of the 250-C20BEngine is complete.

If the eng ine to be converted does not meet this configurtion, all bulletins that are still app licable to the 250-C2must be accomplished prior to or concurrently with theconversion. For example, 250 CEB-1017, Turbine,First and Third-stage Nozzles-Flow Area Changed,would not be applicable to the 250-C20B. The 250-C20Brequir=the new configuration first and third-stagenozzles.Since new parts, e.g., gas promducer and power turbinesupports, are used in the conversion , less time thannormally required to overhaul -the 250-C20 will berequired to accomp lish this bulletin.

MATERIAL AVAILABILITY:Part No. Nom enclature- Qty/As68905306890501

Support Assy, Compressor 1FrontWheel, Compressor, First- 1stage


7/29/2019 CEB1053

6/30

250-C20 CEB-1053P% e 6

COMMERCIAL ENGINE BULLETINENGINE, MODEL 250-C20 SERIES-CONVERSION TO MODEL 250-C20B

MATERIAL AVAILABILITY:Part No.689050268766736890480(l)6878496c2)6886407@)6878498c3)68798676851531(4)6878427688935068885476876676AN12540268890946890481(l)688970068897016889702:;98;;::(5)6876925(@

NomenclatureWhe el Assy, Compressor,Second and Third-stagePlate, ID, Compressor,BlankGearshaft, Spur AdapterFirst-stage Turbine NozzleAssyFirst-stage TurbineWheelSecond-stage Turbine NozzleAssyThird-stage Turbine NozzleAssyFourth-stage Turbine NozzleAssyGas Producer Turbine SupportAssyPower Turbine Support andSeal AssyPower Turbine Support OilSump Cover AssyPlate, ID-Turbine, BlankRivetGasifier Train Idler SpurGearshaftGear-shaft Assy, Spur-Fu elControl & Oil PumpGear, HelicalGearshaft Assy, TorquemeterGearshaft Assy, PTOBearing Assy, RollerBearing Assy, Outer Raceand rollersTube Assy, Oil Filter Inlet

Qty/Assy111111111

1141

1


7/29/2019 CEB1053

7/30

250-(220 CEB-1053Page 7COMMERCIAL ENGINE BUL-LETIN

ENGINE, MODEL 250-C20 SERIES-CONVERSION TO MODEL 250-C2OB

MATERIAL AVAILABILITY:Part No. Nomenclature6876674 Plate, ID, Gearbox, Blank6876333 Tube Assy, Anti-icing, :LH6876294 Tube Assy, Bleed Valve,Air Sensing6886444 Plate, ID, Engine, BlankMS122504 WasherMS35206-241 Screw(1) Optional(2) Reference CEB-1048

&ty/A=y

(3) S erviceable P/N 68784 26 Second-stage Nozzles (referenceCEB-1048) may be reworked to P/N 6878498 per CEB-1054(4) Serviceable P/N 6853277 Fourth-stage Nozzles may bereworked to P/N 6851531 per CEB-1054.(5) Reference CEB-1060(6) Reference CEB-1073

NOTE: Refer to CEB-1055 (CECO fuel control) orCEB-1056 (Bend ix fuel control) for the pro-per parts required to convert the applica-ble control.TOOLING: None

WEIGHT AND BALANCE: Not affected.


7/29/2019 CEB1053

8/30

Te3Peese

toMo

2C2Co

soto2C2B

(S

1o5

D r !2 c Z m m C F 1 z


7/29/2019 CEB1053

9/30



7/29/2019 CEB1053

10/30

250-C20 CEB-1053Page 10

COMMERCIAL ENGINE BULLETIN


7/29/2019 CEB1053

11/30

Te3Peese

toMo2

C2Co

soto2C2B

D l- m


7/29/2019 CEB1053

12/30

Te3Peese

toMo

2C2Co

soto2C2B

(S

5o5

TT

GPb

Amby

L

OiFe

HOUSn

AmbyRewok


7/29/2019 CEB1053

13/30

250-C20 CEB-1053Page 13COMM ERCIAL ENGINE BULLETIN


REFERENCES: 250 CEB-1001, 1003, 1006, 1008, 1009, 1010,1013, 1014, 1020, 1025, 1039, 1041, 1045,1046, 1048, 1049, 1050, 1060, 1061, and 1073The following bulletins must be accomplished con-currently with this bulletin:250 CEB-1054 Turbine Assy, Second-stageNozzle-Rework250-CEB-1055 CECO Fuel Control, Modificationto Common X0-C20/C20B

Configuration or250 CEB-1056 Bendix Fuel Control, Modificationto 250-C20B ConfignrationCW-907, 921, 957, 959, 961, 975, 987, 989, 992,1007, 1008, 1016, 1018, 1020, 1038, 1055, 1077,1100, 1107, 1121, 1166, 1184, 11.92, 1194, 1488


7/29/2019 CEB1053

14/30

250-C20 CEB-1053Page 14

COMMERCIAL ENGINE BULLETINENGINE, M ODEL 250-C20 SERIES-CONVERSION TO MODEL 250-C20B

ACCOMPLISHMENT INSTRUCTIONS:The Accomp lishment Instructions are divided into two sections. Section I identifieand illustrates the components which must be replaced and, if serviceable, re-worked. When rework is required, a separate bulletin is referenced.After Section I is accomplished, including rework described in referenced bulletinall modules and the engine assembly must be reidentified. This is described inSection II.I. Replacement and ReworkNOTE: Conversion to Model 250-C20B does not affect the current assemblyprocedure given in the 250-C20 Over&l Manua l except P/N 6823481-700 Fiberglass Packing is not reinstalled between the power turbinesupport and gas producer rotor assembly because a balance air annu-lus was added in the second-stage nozzle outer band to internally transfer h igh pressure air from within gas producer support to the powerturbine support.

A. Turbine Assembly. Rework P/N 6887195 or 6853329 Gas Producerand Power Turbine Assem blies to P/N 6886443 as follows:1. Rework servicable P/N 6853277 Fourth-stage Nozzle toP/N 6851531 per 250 CEB-1048. (See Figure 1, Sheet 1.)2. Replace P/N 6877143 or 6853278 Third-stage Nozzle Assemblywith P/N 6879867 Nozzle Assem bly.3. Replace P/N 6871452 Gas Producer Support Assembly withP/N 6878427 Support Assembly. (See Figure 1, Sheet 2.)4. Replace P/N 6877399, 6878483, or 6877500 First-stage

Nozzle Assembly with P/N 6878496 per 250 CEB-1048.5. Rework P/N 6871480 or 6887194 Gas Producer Turbine RotorAssembly to P/N 6886445. (See Figure 1, Sheet 3.)

a, Replace P/N 6853306 First-stage Whee l withP/N 6886407 per 250 CEB-1048.


7/29/2019 CEB1053

15/30

250-00 CEB-1053Page 15 COMMERCIAL ENGINE BUL-LETIN

ENGINE, MODEL 250-C20 SERIES-COhJERSION TO MODEL 250-C20B

b. Replace P/N 6871482 Second-stage N ozzle Assemblywith P/N 6878498 Nozzle Assem bly or rework P/N6878426 Nozzle Assembly to P/N 6878498 per 250CEB-1054.6. Replace P/N 6871318 Power Turbine Support and Sea lAssem bly with P/N 6889350 Support and Sea l Assembly.(See Figure 1, Sheet 2.)CAUTION: DO NOT INSTALL P/N 6823481-700 PACKING

BEmEN NEW P/N 6889350 SUPPORT ANDP/N 6886445 GAS PRODUCER ROTOR ASSEMB LY7. Replace P/N 6851526, 6871164 or 6874887 Power TurbineSupport Oil Sump Cover Assem bly with P/N 6888547 CoverAssembly.

NOTE: New production 250-C20 Turbine Assemblies,S/N CAT 31364 and up, incorporate P/N 6888547Cover Assemblies.


7/29/2019 CEB1053

16/30

250-C20 CEB-1053Page16

COMMERCIAL ENGINE BULLETINREWORK SERVICEABLE 6853277FCURTH-STAGE NOZZLE ASSY wPER CEB-1048 TO 6851531

1 SERVICEABLE 6853282THIRD-STAGE WHEELMAY BE REUSED; IFUNSERVICEABLE,INSTALL 6887113

REPLACE 6877143 OR6853278 THIRD-STAGENOZZLE WITH 6879867

250-C20 TURBINE MODULE CONVERSION TO 250-C2OBFIGURE ~(SHEET~ 0~ 3)


7/29/2019 CEB1053

17/30

250-C20 CEB-1053Page17

COMMERCIAL ENGINE BULL.ETlNREPLACE 6851526 6871164, OR

BALANCE AIR TUBES ,/ 1-ELIMINATED ON

6889350 SUPPORT

SUPPORT WITH BALANCE AIR TUBES6889352ELIMjNATED ON

REPLACE 6877399, 6878483, OR6877500 FIRST-STAGE NOZZLE

/-WITH 6878496 PER CEB-1048

- REPLACE 6871452 GASPRODUCER SUPPORTWITH 6878427

250-C20TURBINEMODULE CONVERSIONTO250-C20BFIGUREl(SHEET 2 OF 3)


7/29/2019 CEB1053

18/30

250-C20 CEB-1053Page18


REIDENTIFY GAS PRODUCER ROTORASS Y AS 6886445 (APPLY P/N ONSECOND-STAGE NOZZLE PERAS478-2Dl OR 2E)

3306 FIRST-STAGE

REPLACE 6871482 SECOND-STAGE NOZZLEASSY WITH 6878498 OR REWORK 6878426NOZZLE ASSY TO 6878498 PER CEB-1054

250-C20 TURBINE MODULE CONVERSIONTO 250-CZOBFIGUREl(SHEET 30F 3)


7/29/2019 CEB1053

19/30

250-C20 CEB-1053Page 19 COMMERCIAL ENGINE BULLETIN


B. Compressor Assemb ly. Rework P/N 6853337 Compressor Assemblyto P/N 6890550 as follows:1. Replace P/N 6878418 Compressor Front Support Assem bly withP/N 6890530 Support Assembly. (See Figure 2, Sheet 1.)

NOTE: New production 250-C20 Compressor Assem bliesS/N 38262 and up, incorporate the new P/N 6890530Support Assembly.2. Rework P/N 6876772 Compressor Rotor Assembly to P/N6890529 as follows (Figure 2, Sheet 2):

a. Replace P/N 6876651 First-stage Whee l with P/N 6890501Wheel.b. Replace P/N 6876652 Compressor Second and Third-stageWhee l Assem bly with P/N 6890502 Wheel Assembly.

3. If previously installed, P/N 6876360 Spur Adapter Gearshaftwith P /N 6890480 Gearshaft (Figure 2, Sheet 3). It is optionalto replace P/N 6851537 Gearshaft with P/N 6890480; PF6890480 which incorporates the modified involute profile ofthe 17-tooth gear for smoother operation is released to the250-C20B on a use stock basis. If P/N 6851537 Gearshaftis rejected at overhaul, it is recommended to install the newP/N 6890480 Gearshaft.

I 4. OPTIONAL : Replace ~P/N 6887189 Rear Diffuserwith P/N 6851430. Use P/N 6887121 Vent Tube with P/N6851430 Diffuser.C. Power andAccesso ry Gearbox Assemb ly. Rework P/N 6877180Gearbox Assem bly to P/N 6886442 as follows: (see Figure 3.)

1. E previously installed, replace gearbox covers with thin castwalls and only three supporting ribs with P/N 6886448 CoverAssemblies.2. Replace P/N 6853347 Gasifier Train Idler Spur Gearshaft withP/N 6889094 Gear-shaft (Figure 3, Shee t 1).

Revision No. 1April 1, 1983Pub1 ished November 17, 1975Rolls-Royce Proprietary Data Uncontrolled Printed Copy

7/29/2019 CEB1053

20/30

250-C20 CEB-1053Page20

COMMERCIAL ENGINE BULLETINENGINE, MODEL250-C20SERIES-COWERSIONTOMODEL250-C20B

WITH 6890530TRANSFER ALL DATAFROM OLD ID PLATEEXCEPT REIDENTIFYAS 6890550 AND ADLETTER F AS SUFFIXTO SERIAL NUMBER

250-C20 COMPRESSOR MODULE CONVERSION TO 250-C20BFIGuRE~(SHEET~~F 3)


7/29/2019 CEB1053

21/30

250-C20 CEB-1053Page 21

COMMERCIAL ENGINE BULLETINENGINE, MODEL 250-C20 SERIES-CONVERSION TO MODEL 25%C20B

REPLACE 687665 1FIRST-STAGE WHEELWITH 6890501

REIDENTIF( ROTOR ASSYAS 6890529 (ELECTROCHEMICALLYREPLACE 6876652 ~- -~/.~~~-ETCH P/N ON IMPELLER REARFACE PER AS478-7A2)SECOND p. THIRD-STAGE

_-_~_,~.~~-~a~~WHEEL ASSY WITH 6890502/l

250-C20 COMPRESSOR MODULE CONVERSIONTO250-C20BFIGURE 2 (SHEET~OF 3)


7/29/2019 CEB1053

22/30

250-C20 CEB-1053Page22


Revision No. 1April 1,1983Published November 17, 1975Rolls-Royce Proprietary Data Uncontrolled Printed Copy

7/29/2019 CEB1053

23/30

I

ALLISON GAS TURBINECommercial Engine Bulletin1. PLANNING INFORMATION: (Continued)

(31

(4)

Replace P/N 6824733 Roller Bearing at the forward position of thePTO gearshaft with P/N 6887772 or P/N 6824734 Bearing (Figure 3,Sheet 2).Replace the following gasifier and power train gears and gearshafts(Figure 3, Sheets 1 and 2). The new gears and gearshafts havemodified tooth profiles for smoother operation, reducing vibrationand noise.

SupersededNew Part No. Nomenclature Pat-t No.6890481 Gearshaft Assembly, Spur- 6870769

Fuel Control and Oil Pump68897006889701

Gear, HelicalGearshaft Assembly, Tor-quemeter

6871314 (optional)6870941

6889702 Gearshaft Assembly, PTO 6853339(5) Replace P/N 6875027 No. 2-l/2 Roller Bearing and Outer Race

Assembly with P/N 6890914 Bearing Assembly per CEB-1060 (Figure 3,Sheet I).

(6) Replace P/N 6870742 Oi l Filter Inlet Tube Assembly with P /N 6876925Tube Assembly per CEB-1073 (Figure 3, Sheet 3).El. Enqine Electrical Svstem. All 250-C2OB electrical system componentsand parts are identical to the 250-C20 except do not use P/N 6875705

and P/N 6876282 Start Counter Assemblies .E. Enqine Anti-icinq and Bleed Air Systems. Replace the following parts

if installed (see Figure 4).

New Part No. Nomenclature Superseded&iyt No.68763336876294

Tube Assy , Anti-icing, LH 6850596Tube Assy , Bleed Valve, Air 6871466Sensing

November 17, 1975Revision 2August 1, 1988

250.C20 CEB-1053Page 23 of 30


7/29/2019 CEB1053

24/30


2. PLANNING INFORMATION: (Continued)

REPLACE 687502768YUY14 t+R CEB-1060

imc

BEARING WITH,^^^^ _. _-~ ~-~

OPTIONAL: REPLACE 6871314

IF INSTALLED, REPLACECOVERS WITH THIN CASTWALL AND ONLY THREESUPPORTING RIBS WITHP/N 6884448I

HELICAL GEAR I IWITH 6885700

tREPLACE 6870941TORQUEMETERGEARSHAFT WITH6889701

-ACE 6853347 GASIFIERTRAIN IDLER SPURGEARSHAFT WITH 6889094

c;k,S:R DATAFROM OLD ID PLATEEXCEPT REIDENTIFYAS 6886442 AND ADDLETTER F AS THEONLY SUFFIX TOTHE SERIAL NUMBER

REPLACE 6853339PTO GEARSHAFTWITH 6889702

250-C20 GEARBOX MODULE CONVERSION TO 250.C2OBFIGURE 3 (Sheet 1 of 3)

November 17, 1975 250-c20 CEB-1053Revision 3February 15, 1991 Page 24 of 30


7/29/2019 CEB1053

25/30



fOPTIONALREPLACE 68069F/C 8 OIL PUMP

@ GEARSHAFT WITH689048 1

SERVICEABLE 6856360T/M SUPPORT SHAFTMAY BE REUSED; IFUNSERVICEABLE,INSTALL 6859367

REPLACE 6824733BEARING WITH6887772 OR 6824734

SERVICEABLE 6852087GEARSHAFT MAY BEREUSED; IF UNSERVICEABLE,INSTALL 6854857

250.C20 GEARBOX MODULE CONVERSION TO 250-C2OBFIGURE 3 (Sheet 2 of 3)

November 17, 1975 250-c20 CEB-1053Page 25 of 30


7/29/2019 CEB1053

26/30

ALLISON GAS TURBINECommercial Engine Bullet in


SERVICEABLETUBE MAY BE REUSED;IF UNSERVICEABLE,INSTALL 6840115

SERVICEABLE 6845947 REPLACE 6870742 TUBETUBE tdAY BE REUSED; WITH 6876925 PERIF UNSERVICEABLE, CEB-1073INSTALL6876263

250-C20 GEARBOX MODULE CONVERSION TO 250.C2OBFIGURE 3 (Sheet 3 of 3)

November 17, 1975 250-C20 CEB-1053Revision 3February 15, 1991 Page 26 of 30


7/29/2019 CEB1053

27/30

250-C20 CEB-1053Page 27


1EPLACE 6871466 TUBE ,; \(IF INSTALLED) WITH ! ,,:..~, :-::~f;68762 !94

REPLACE 6650596 TUBE\(IF INSTALLED) WITH6876333

ENGINE AIR SYSTEMS (ANTI-ICING AND BL:EED AIR)FIGURE 4


7/29/2019 CEB1053

28/30

250-C20 CEB-1053Page 28

COMMERCIAL ENGINE BULLETINENGINE, MODEL 250-C20 SERIES- CONVERSION TO MODEL 250-C20B

F. Fuel Control Systems.1. Refer to 250 CEB-1055 for instructions to modify the 250-C20CECO Fue l Control to the common 250-C20/C20B configuration.2. Refer to 250 CEB-1056 for instructions to modify the 250-C20Bend ix Fue l Control to the 250-C20B configuration.NOTE: All other 250-C20 Bendix an d CECO components and plumbinghardware (e. g., tubing, accumulators, brackets, clamps, etc.)

are identical to the 250-C20 Bend ix and CECO fuel controlsystems.n. Reidentification

A. Obtain a new P/N 6876673 Compressor Assembly Identification Plate(Blank).1. Transfer all information from the old plate except the compressorassembly part number and the engine model. Identify the com-pressor assembly as 6890550 and the model as 250-C20B.

Also, add the letter F as a suffix to the compressor serial number.Information may be metal stamped, vibropeened or scribed.2. Install new identification plate to the compressor front support-to-compressor case splitline.

B. Obtain a new P/N 6876674 Gearbox Assembly Identification Plate(Blank).1. Transfer all information from the old plate except the gearboxassembly part number, engine mode l and any existing gearboxserial number suffix letter. Identify the gearbox assembly as6886442 and the m odel as 250-C20B. Also add the letter F as asuffix to the gearbox serial number. Information may be metalstamped, vibropeened or scribed.2. Install new identification plate, using two MS122054 Washers andMS35206-241 Screws.


7/29/2019 CEB1053

29/30

250,-C20 CEB-1053Page 29


C. Obtain a new P/N 6876676 Turbine Assem bly Identification Plate(Blank).1. Transfer all information from the old to the new plate except theturbine assembly part number, engine model, and any existingturbine seria l number suffix letters. Identlify the turbine assemblyas P/N 6886443 and the model as 250-C20B. Also, add the letterF as a suffix to the turbine serial number. Information may bemetal stamped, vibropeened or scribed.2. Install new identification plate, using four AN125402 Rivets.

D. Obtain a new P/N 6886444 Engine Identification Plate (Blank).1. Identify CECO-controlled engine assembly as P/N 6886440,the engine model as 250-C20B, T. C. No. as E4CE andP. C. No. as 310. Transfer the exact engine serial numberfrom the old plate, except any existing suffix letters. Add theletter F as a suffix to the engine serial num.ber.2. Identify Bendix-controlled engine assembly as P/N6887190,

the eng ine model as 250-C2OB,T. C. No. as E4CE and P. C.No. as 310. Transfer the exact eng ine seri.al number fromthe old plate except any existing suffix letters. Add the letterF as a suffix to the engine serial number. Information may bemetal stamped, vibropeened or scribed.3. Install new identification plate, using two MS122054 Washersand MS35206-241 Screws.NOTE: Engines reidentified as described must incorporate (1)the CECO fuel control as defined in 250 CEB-1055 with

the current CECO fuel control system ciefined in thelatest 250-C20 illustrated parts ca talog revision or (2)the Bendix fuel control as defined in 250 CEB-1056 withthe current Bend ix fuel control system defined in thelatest 250-C20 parts catalog revision.E. Log Book Compliance

1. On every page where the engine model is called out, add theletter B after 250-C20.


7/29/2019 CEB1053

30/30

2.

3.


PLANNING INFORMATION: (Continued)2. Enter bulletin compliance and other component compliance as required.

Be sure to note inal l applicable places the suffix to the engine andmodule seria l numbers.NOTE: All engine conversion kits manufactured by Allison since April1988 have been serial ized to improve tracabi lity of

components. All ison Model 250 Conversion Report (FormV009J-WH) must be completed and filed with All ison ProductSupport for each converted engine.

MATERIAL INFORMATION:3. Refer to the Accomplishment Instrucitons and corresponding

illustrations of the bulletin for Material Information.Disposition of the removed 250.C20 parts is to be determined by thedistributor accomplishing the conversion.

PRODUCT SUPPORT

Allison Engine Company

November 17, 1975 250.C20 CEB-1053

CEB1053

Documents

Transcript of CEB1053