TB
1-1520-240-20-94
Task/Inspection Suspense Date. Within 10 hours/14 days.
2.
3.
Summary of the Problem.
4.
a. In 1993, several incidents were reported of the 5,000 pound tie-down rings unscrewing and pulling
loose from the cabin floor. These tie-down fitting rings are routinely used to secure the flight engineer/crew
member's safety harness. Investigation revealed that the cause of the problem was missing MIL-S-22473
sealant on the retaining bushing thread, and seizure of the bushing due to paint overspray, allowing the tie-
down ring to unscrew on rotation.
b. Referenced message, CH-47-94-ASAM-05 (TB 1-1520-240-20-71), 25 April 1994, was issued to
inspect fielded CH/MH-47 aircraft, and action was to be taken by Boeing Helicopters (BH) to inspect aircraft
on the production line prior to delivery.
c. Recently, during flight operations of an Australian CH-47D aircraft, the forward right hand tie-down
fitting on the ramp backed out of the adapter while the flight engineer was using the tie-down fitting to secure
his safety harness. Investigation revealed the absence of sealant on the threads of the adapter and bushing,
and no conclusive evidence that the aircraft had been inspected/corrected prior to delivery by BH.
d.
For manpower/downtime and funding impacts, see paragraph 12 below.
e. The purpose of this TB is to inspect/correct those CH/MH-47 aircraft that were not covered by the
referenced TB (see paragraph 13a below), and to establish a recurring phase maintenance (200 hour) inspec-
tion requirement for all aircraft of the cabin floor and ramp 5,000 pound tie-down fittings for serviceability to
ensure the safety of the flight engineer/ crew member when using the safety harness.
5. End Items to be inspected. All CH-47D, MH-47D, and MH-47E aircraft, serial number 92-0308 through
93-0934.
Assembly Components to be Inspected.
6.
PART NUMBER
NATIONAL STOCK NUMBER
NOMENCLATURE
114S2893-6
Receptacle Assy, Tie-Down
Receptacle Assy, Tie-Down
114S2893-13
7.
Parts to be Inspected.
NOMENCLATURE
PART NUMBER
NATIONAL STOCK NUMBER
Ring, Tie-Down
114S2801-1
N/A
22622-51
Adapter, Tie-Down
1670-01-928-6296
114S2828-1
Bushing, Sleeve
3120-01-374-9312
Inspection Procedures.
8.
a. Inspect all 5,000 pound tie-down receptacles in the cabin floor and ramp for serviceability, see
TM 55-1520-240-23-2, Task 2-205.1 or TM 1-1520-252-23-3, Task 2-109.1.
b. If the ring starts to unscrew or screws out of the cabin floor/ramp, the assembly is suspect and must
be repaired or replaced. Proceed to paragraph 9 for corrective procedures.
c. If the ring can be rotated by hand in both directions, no further action is required. Record and report
compliance in accordance with paragraph 14 below.
d. Henceforth, all CH-47D, MH-47D, and MH-47E aircraft shall be inspected for serviceability of cabin
floor and ramp 5,000 pound tie-down fittings in accordance with Task 2-190.1 or Task 2-205.1 of referenced
TMs (see paragraphs l3b and 13c below) at each phase maintenance (200 hour) inspection interval.
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