TB 1-1520-238-20-99
s.
Separate 2408-16-1. N.
t.
Higher -16-1. N.
u.
TASN Item. N.
v.
2410 Required. Y.
w. Federal Manufactures Code. 02731.
x.
TBO/Replacement. 750.
y. Reference or Source Document. Added, TB 1-1520-238-20-99, dated 19 No-
vember 1999.
(2) If TSN hours exceed 750, follow the procedures in 9.b.
e. If any of the following fault events occur during aircraft operation, proceed to the correction proce-
dures in paragraph 9.a.
(1) The APU will not start (hang-start) and no deficiencies are noted during normal APU trouble-
shooting (not an APU problem).
(2) The APU moves rotor system during APU start.
(3) Engines fail to operate the accessory gearbox when the Np/Nr is advanced beyond 95 per-
cent.
(4) Accessory gearbox seizes.
(5) Pilot notes simultaneous failure of AC electrical, hydraulic, and pneumatic subsystems.
9.
Correction Procedures.
a.
If any of the faults listed in paragraph 8.e. occur while operating the aircraft:
(1) Replace the main transmission.
(2) Submit a category 1 deficiency report.
b. If any of the serial numbers match those listed in paragraph 8.b., or the main transmission TSN ex-
ceeds 750 hours, contact the LOG POC in paragraph 16.b. and report the following data:
(1) Reference this TB number.
(2) Date of the inspection.
(3) Aircraft serial number(s).
(4) Main transmission part number and serial number.
(5) Main transmission TSN and Time Since Overhaul (TSO).
c. If the LOG POC confirms that the primary and secondary clutch assemblies inside the transmission
accessory gearbox have exceeded 750 operating hours, change the aircraft status to a red //X//. The red
//X// entry shall state, "Replace main transmission in accordance with TB 1-1520-238-20-99." Follow-on in-
structions from the LOG POC will provide disposition and requisition instructions. Aircraft on red //X// status
symbol will be maintained in flyable storage with ground run-ups authorized.
d. Repeat the inspection procedures in paragraph 8 for the replacement transmission before installing
it, to verify its serviceability.
10. Supply/Parts and Disposition.
a.
Parts Required. Main Transmission, NSN 1615-01-252-6376, will be required to replace defective
items.
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