TB 1-1520-240-20-83
*
2.
Task/lnspection Suspense Date. Within 10 flight hours or 30 days.
3.
4.
Summary of the Problem.
a. During the scheduled maintenance of a rotor head assembly, tape was discovered covering one of six oil lube
ports on the upper surface of the rotor hub. These ports are used to provide lubrication to the horizontal hinge
pin bearings. The tape is used to protect the oil passages during painting and may have been accidentally left in
place during overhaul production. A complete or partial restriction of lubricating oil to the horizontal hinge pin
bearings causes premature wear and results in damage to the bearings and related components.
b. For manpower/downtime and funding impacts, see paragraph 12.
c. The purpose of this TB is a one time inspection of all CH-47D, MH-47D, and MH-47E forward aft rotor hubs to
ensure flow of lubricating oil to the horizontal hinge pin bearings. Rotor hubs received from the supply system
shall have this TB complied with prior to installation on the aircraft.
5. End Items to be Inspected. All CH-47D, MH-47D, and MH-47E aircraft.
6. Assembly Components to be Inspected.
NOMENCLATURE
PART NUMBER
NATIONAL STOCK NUMBER
FWD ROTARY WING HEAD
145R2003-10
1615-01-301-4398
145R2003-9
145R2003-6
145R2003-5
1514-01-345-0477
145R2003-4
145R2003-3
AFT ROTARY WING HEAD
145R2004-20
145R2004-18
145R2004-12
145R2004-1 0
145R2004-8
145R2004-6
145R2004-2
7. Parts to be Inspected. N/A.
8. Inspection Procedures.
NOTE
If the 400 hour hinge pin inspection has already been accomplished IAW TM 55-1520-240-23-1, Task 1-92
or TM 1-1520-252-23-1, Task 1 -100 the inspection is complete. This inspection is required on all rotor
hubs received from the supply system prior to installation on the aircraft.
a. Remove lockwire (MS20995NC32) from drain plug (AN814-2L or MS24391 -2L) located below each horizontal
hinge bearing on the rotor (12 per A/C).
b. Remove lockwire (MS20995NC32) from one (1) of the three (3) filler plugs (AN814-5DL) located on top of the
horizontal hinge pin bearing (main) oil tank mounted on top of the rotor hub. Two (2) tanks per A/C.
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