ALERT

ENGINE, FUEL AND CONTROL - REPLACE P/N 6848471

AND 23051141 TUBE ASSEMBLIES
1. Pi ANNING INFORMATlOhL
A. Effectivity:
(1) All Allison Model 250x20, X208 (T63-A-720) and -CZOJ Series engines are affected
by this Bulletin as follows:

w Serial NQ~

250x20 CAC 820000 through 8.23567

250<20B CAE 830000 through 8:36440
CAE 836442 through 836451
CAE 836453 through 8:36456
r6%A-720) AE 404229 through 405321
25O&C2OJ CAE 27000: through 270488
25O-c2OJ CAE 272501 through 272610

(2) Model 250x20 Series engines modified in accordance with 250 CEE1285.
(3) New production engines which have the P/N 23051141 Tube installed are as follows:

Engine Serial Numbers

270489 405319 836457 836473 836489

270490 405322 836458 836474 836490
27049: thru 836459 836475 836491
270492 405352 836460 836476 836492
270493 405354 836461 836477 836493
270494 thru 836462 836478 836494
270495 405397 836463 6364'9 836495
270496 405399 836464 836480 836496
270497 thru 836465 H364Ul 836498
270498 405431 836466 836482 836499
270499 405433 836467 a36483 836501
270500 405436 836468 836484 836502
270501 836441 836469 836485 836503
270502 836452 836470 836486 836504
270503 836453 836471 836487
405318 836456 836472 83648,8

8. Reasons:
(1) The P/N 6848471 Siroli-to-P, Filter Tube Assembly is susceptible to maintenance
mishandltng damage. A new scroll-tc+P, filter tube Assembly is released to mmimuze
this mishandlmg damage. The P/N 6848471 Tube will continue to be used on some
Series II turbines between the turbine pressure oil check valve and the horizontal firewall
oil fiting

July 20. 1990 25O-C20, X2OB fT63-A-720). -C2OJ CEKA-1294

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1. PLANNING INFORMATION: (continued)

(2) Allison has become aware of a quality problem that pertains to the initially-released PIN
23051141 Tube Assembly installed during production and in accordance with CEB 1285.
N&Y&E: These parts will be furnished free of charge until April 30, 1991.
(3) Compliance with this bulletin eliminates the required 100 hour inspection of the
I scroll-to-filter P, tube assembly. (Reference CEB-A-1234.) However, the new tube
must continue to be inspected per the Operation and Maintenance Manual any time it is
removed.
C. Descriotiw:
The new 2305114 7 Scroll-t&P, Filter Tube Assembly has a thicker wall and improved
routing/configuration. Both of these features increase durability and resistance to handling
damage.
The initially-released new P, Tube was identified as P/N 23051141. However, because of the
quality problem with some of these tubes. P/N 23051141 Tube Assemblies are to be removed
from service and returned to an Allison distributor.
The replacement tube for P/N 6848471 or P/N 23051141 is either of the following:
(1) PIN23054628
OR
(2) P/N 23051141 having the letter P vibropeened on one of the flats of the “B” nut on the
filter end.
All of the tubes have stamoinq marks on the “B’ nut (i.e. AN, J, E). The letter P is a
separate marking on one of the other Rats.
A P/N 23051141 Tube that has the letter P vibropeened on the “W nut does not require
repiacement.
The 23051141 with a P and the 23054628 are identical tube configurations. The P/N’s
and markings are the only difference between these two tubes.
D. Aoproval:
Technical aspects are FAA approved.
E. Comoliance:
(1) Engines with P/N 6848471 Tube:
Compliance Code 2: Compliance required within the next 50 flight hours or no later than
June 30. 1991, whichever comes first, following parts availability at the Distributor.
(2) Engines with P/N 23051141 Tube:
Compliance Code 2: Compliance required at the next 100 hour inspection, but in no case
later than October 1, 1990.
(3) Upon compliance with CEEA-1294 me following information must be supplied to the
local distributor for transmittal to Allison:
(a) Operator name.
(b) Engine SIN.
(c) Time since new (TSN).

July 20, 1990 250-C20, -C2OB (T63-A-720). -C2OJ CEEA-1294

Revision No. 2
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 Allison Engine Company
COMMERCIAL ENGINE BULLETIN

!. PLANNING INFORMATION: (contwedj

F. B
Not affected.
G. Material Availabilih:

New Pan NQ Nomenclature Mr ktQ!le!

23051141’ Tuba Assembly, P, Air- Scroll-twP, Fifter 1 c20,
C2OB (TS3-A-720).
C2OJ

23054628 Tube Assembly, P, Air- Scroll-tr+P, Filter 1 c20,

C2OB (T63-A-720).
C2OJ

‘Tubes of P/N 23051141 which have a letter P tibropeened on one ,of the flats of the “B” nut
(on the filter end) are acceptable. If the tube does not have the letter P identification, it is
WJACCE PTA P F and must be replaced.
H. Tm
None.
I. Weiaht
Not affected.
J. m
Not affected.
K. References:

I CW 5031, CW 5232,250<20 CEB-1285. CEB-1234.

L. Other Publicatrons Affected:
(1 j 1OW2 Operation and Maintenance Manual, Turtxxhaft Models :!5O-C20. -C206, -C2OJ
(2) 1 OW4 Parts Catalog, Turboshaft Models 250420, -C2OB. -C2OJ
M. i!&w&j&
The work required by this Bulletin shall be accomplished in place of Bulletin No. 250x20
CEB-1285.
2. ACCOMPLISHMENT INSTRUCTIONS:
A. Remove me 6648471 or 23051141 P, Tuba. Loosen the P, filter damp and loosen the P,
filter to governor tee “B” nut at me P,: filter.
(1) Using the proper size bac&up wrench on me fitting, disconnect the coupling nut that
joins the P, tube assembly and compressor scroll fitting.
(2) Hold the P, filter assembly by placing Me proper size wrench on the large Rats of me
housing or filter assembly. Disconnect the remaining scroll to filtr?r P, tube coupling nut
and remove the tube. Remove the filter to governor tube coupling nut at the filter.
Loosen me clamp securing the P, filter to the gearbox.

July 20, 1990 250420. -!Z2OE (T63-A-720). -C2OJ CEB-A-1294

Revision No. 2
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COMMERCIAL ENGINE BULLETIN

2. ACCOMPLISHMENT INSTRUCTIONS: (continued)

B. Install the Scroll-to-P, Filter Tube Assembly, P/N 23051141, (“B” nut marked with a letter P)
or 23054628 to Me compressor scroll and P, filter as follows:
CAUTION: FAILURE OF ENGINE PNEUMATIC TUBES CAN CAUSE FLAMEOUT OR POWER
LOSS.
(1) Tube assemblies must fit and be aligned witi the mating flare tube fittings to the degree
that at both ends of the assembly the flares shall ba uniformly seated in a free state on
the cones of the mating fittings. The fit shall be without distortion or stretching of the tube
assembly and to the degree that the nuts can be fully engaged up to the final one-half
turn with light finger pressure. In the event that the tuba does not align with the mating
fittings, reposition the scroll fitting and/or P, filter assembly to me degree that proper
alignment may be attained. Remove lockwire to do this, and then replace lockwire. Final
tightening of this fining must be accomplished before the tube assembly is connected.

CAUTION: THE PRACTICE OF TIGHTENING FITTING LOCK NUTS WITH TUBE

ASSEMBLIES INSTALLED CAN RESULT IN DAMAGE TO THE TUBE WITH
POSSIBLE FAILURE OF THE TUBE ASSEMBLY RESULTING IN A POWER
LOSS.
(2) Hold the filter with the proper wrench at the hex flats of the filter assembly, while
tightening the coupling nut to 80-120 lb in. (9.0-13.6 N-m). Tghten P, tuba to scroll
coupling nut to 80-120 lb in. (9.0-13.6 N,m).
(3) Tighten clamp securing P, filter to the gearbox.
(4) Install filter to governor tee coupling nut. Torque nut to 80-120 lb in. It may be
necessary to adjust the filter to governor tuba to achieve proper tube to fitbng alignment.
See Operations and Maintenance Manual for rigid tube installation procedures.
-C. Record compliance in me Engine Log Book, Engine Assembly (white pages) Part Ill,
Modification Record as applicable with the following:

250X20, -C20B (T63-A-720) , -C2OJ CEEA-1294

July 20. 1990 250x20, -C2OB (T63-A-720), -C2OJ CEB-A-1294

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3. MATERIAL INFORMATION:

A. Basis for quanhties is per engine assembly.

8. Bill of material:

Instructions!
New P/N QIY Nomenclature. QJPJQ QQ Disoosibon
23051141’ 1 Tube Assembly 6848471 1 1
0‘ P, Air - Scroll& Or
23054628 t+P, Filter 23051141 1 2

‘Tubas of P/N 23051141 which have a letter P vibropeened on one of the flats of the ‘8” nut (on the filter
end) are acceptable. If the tube does not have the letter P identification, it is WCFPTABCE and must
be removed.

lNSTRUCTlONS/DlSPOSlTlON NOTES:
1. Scrap removed item.
2. Return to an Allison authorized Repair/Overhaul facility for transmittill to Allison

CUSTOMER SUPPORT
ALLISON ENGINE COMPANY

July 20, 1990 250~2O.-c208 (T63-A-720), -C2OJ CEEA-1294

Revision No. 2
October 31, 1996 Page 5 of 5

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