TB 1-1520-240-20-88
f. Component/Parts in Stock at All Levels (Depot and Others) Including War Reserves Upon receipt of this TB the
materiel condition tags of all items in all condition codes listed in paragraph 6 and 7 shall be annotated to read 'TB 1-
1520-240-20-88, One Time Visual Inspection of Forward Transmission Main Lubrication Pumps, not complied with.
(1) Wholesale Stock Report receipt of this TB in accordance with paragraph 13c(2).
(a) Upon receipt of this TB all serviceable items (condition codes " ", " " " " " " and "E" listed in
A B, C D,
)
paragraph 6 located in wholesale depot storage shall be placed in condition code NJ' and tagged with a suspended
tag/label materiel, DD Form 1576/DD Form 1576-1. Report compliance in accordance with paragraph 13d(1). Do not
remove original condition tags.
(b) Upon receipt of this TB inspect all serviceable items (condition codes "A", " , " " "D' and " " listed
B C,
E)
in paragraph 7 in accordance with paragraph 8. Classify items determined to be discrepant in condition code "D" and
prepare a test/modification tag materiel, DD Form 1576. Reference this TB in the authority block. Serviceable items are
to remain in the original condition code. Indicate compliance with this TB in the authority block Report compliance with
this TB in accordance with paragraph 13d(1).
(2) Retail Stock Report receipt of this TB in accordance with paragraph 13c(1). Upon receipt of this TB
commanders and others maintaining retail stock at installation level and below shall contact the supported aviation unit to
perform the inspection required by paragraph 8 and the correction procedures of paragraph 9 on discrepant materiel.
Classify items in paragraph 7 determined to be discrepant in condition code " " and prepare a test/modification tag
K"
material, DD Form 1576. Reference this TB in the authority block Disposition of discrepant material will be in
accordance with paragraph 10. Report compliance with this TB in accordance with paragraph 13d(2).
g. Components/Parts in Work Al items listed in paragraph 6 and 7 below shall not be issued until compliance with
this TB has been completed.
2. Task/Inspection Suspense Date Within 10 flight hours or 14 days from receipt of superseded message or receipt of
this TB, whichever is received first.
4. Summary of the Problem.
a Two (2) 145DS102-3 forward transmission main lubrication pump shafts have failed in service. The pump shaft
fractured causing the output pressure of the pump to decrease. The failures consisted of a fracture of the pump shaft
between the two gerotors resulting in only one gerotor being driven and a reduction of main oil pressure to five to seven
psi. The shaft failures were determined to be the result of bending fatigue with the origin at a manufacturing defect
(crack) in the snap ring groove. Our investigation concluded that the cracks were caused by shaft straightening after
hardening.
b. Three (3) additional pump shafts inspected exhibited cracks. All five of the above failures were from the same
manufacturing work order (i.e., lot). Five (5) additional manufacturing lots of pump shafts have been inspected and no
cracks have been found. The suspect lot of 1 45DS102-3 forward transmission lubrication pumps consists of serial
number V534 through V598. The probability of a suspect pump malfunction is increased over that of a non-suspect
pump.
c. Based on data obtained during forward transmission auxiliary oil system testing, it is likely that after a main
lubrication pump malfunction the transmission oil pressure master caution warning light will illuminate followed by
illumination of the forward transmission oil hot master caution warning light. Illumination of these warning lights requires
compliance with published emergency procedures, i.e., land as soon as practicable. It should be noted that malfunction
of a main lubrication pump will not affect auxiliary oil pressure within the forward transmission.
d. The suspect forward transmission lubrication pumps are to be removed from service, reworked, and identified
with the letters " W" after the serial number on the pump identification plate.
R
e. For Manpower/Downtime and Funding Impacts See paragraph 11 below.
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