TB 1-1520-240-20-102
g. Component/Parts in Work (Depot and Others). Items listed in paragraph 6 in work will not be issued until
compliance with this TB is complete. Report compliance with this TB in accordance with paragraph 14d(2).
2. Task/Inspection Suspense Date. The task/inspection suspense date shall be within the next 10 flight hours or 14
days from the date of issuance of the ASAM, whichever comes first.
3.
4.
Summary of the Problem.
a. Detailed investigation has identified 23 aft transmissions that have been overhauled with improper shimming of
the input shaft. This deficiency causes excessive vibration of the transmission and premature wear of the input pinion
gear and its mating gear. The shimming procedure has been corrected by tool modification, and all aft transmissions
overhauled after 8 December 1997 are not considered suspect The reference message/memorandum in paragraph 13
was sent in attempt to locate these specific transmissions and expedite the process. It had some success in locating
some of the 23 transmissions. This TB requires a visual check of the transmission data plate.
b. For manpower/downtime and funding impacts, see paragraph 12.
c. The purpose of this TB is to require a one time inspection of all aft transmissions with the purpose of finding
suspect improperly shimmed aft transmission and to provide time since overhaul of transmission, aircraft serial number,
and transmission serial number. A serial number listing of the suspect aft transmissions are listed in paragraph 8.
5.
End Items to be Inspected. All CH/MH-47D/E aircraft.
6.
Assembly Component s to be Inspected.
NOMENCLATURE
PART NUMBER
NATIONAL STOCK NUMBER
Aft
Transmission Assy
145D2300-3
Aft
Transmission Assy
145D2300-4
Aft
Transmission Assy
145D2300-5
Aft
Transmission Assy
145D2300-7
7.
Parts to be Inspected. N/A.
8.
Inspection Procedures.
NOTE
Units that have performed a visual serial number inspection of aft transmissions
data plate per the message given in paragraph 13 may enter this TB or ASAM CH-
47-98-ASAM-04 as having been complied with on the aircraft records.
a. Visually inspect all aft transmissions for the following serial numbers:
A9-022
A9-035
A9-036
A9-046
A9-052
A9-055FO
A9-058
A9-088FO
A9-105FO2
A9-122
A9-127
A9-129FO
A9-132
A9-140FO
A9-161
A9-216
A9-253FO
A9-260FO
A9-291
A9-375
A9-513
A9-572
A9-605
2
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