TB 1--1520--248--20--48
4. Summary of the Problem.
a. Numerous reports from the field have indicated cracking of the oil cooler support panel in the area of the forward
fanshaft bearing support inserts. A recent report indicated a cracked forward fanshaft bearing support bracket in addi-
tion to the cracked panel. The cause of cracking of the oil cooler support panel and support bracket are under investiga-
tion. One potential cause is an imbalance of the oil cooler fan caused by a disproportionate buildup of foreign material.
A one time and recurring inspection of the fan will be initiated by this TB. In addition to the requirements of this TB,
compliance with URGENT TB 1--1520--248--20--47, One Time Inspection and Repair of Oil Cooler Support Installation,
P/N 406--030--117--125/129 on OH--58D Helicopter is required in accordance with paragraph 2. Task/Inspection Sus-
pense date of the TB. This TB contains detailed inspection and repair of the support panel.
NOTE
This TB requires TB 1--1520--248--20--47 dated 31 December 1999 be recorded and complied with
by the suspense time frame provided in TB 1--1520--248--20--47. TB 1--1520--248--20--47 was initially
assigned to supercede OH--58--99--ASAM--05 and OH--58--99--ASAM--07 however this action was
not completed. Do not confuse requirements of OH--58--99--ASAM--05 and OH--58--99--ASAM--07
with TB 1--1520--248--20--47. TB 1--1520--248--20--49 will be issued to supercede
OH--58--99--ASAM--05 and OH--58--99--ASAM--07.
b. For manpower/downtime and funding impacts. See paragraph 12.
c. The purpose of this TB is to is threefold:
(1) Initiate a One Time Inspection of oil cooler support panel and forward fanshaft support bracket for cracks.
(2) Initiate a One Time and Recurring Inspection of oil cooler fan for cleanliness at every other 40 hour Progressive
Phase Maintenance (PPM) Inspection.
(3) Establish a One Time Inspection of oil cooler support installation P/N 406--030--117--125/129 in accordance with
TB 1--1520--248--20--47.
5. End Items to be inspected. All OH--58D aircraft.
6. Assembly Components to be Inspected..Not applicable.
7. Parts to be Inspected.
NOMENCLATURE
PART NUMBER
NATIONAL STOCK NUMBER
Oil Cooler Support Installation
406--030--117--125
1560--01--356--6007
Oil Cooler Support Instalation
406--030--117--129
1560--01--445--3364
Bracket FWD, Tail Rotor Bearing
406--040--323--101
1615--01--236--9653
Impeller, Oil Cooler
206--061--432--117
1615--01--359--6063
a. Inspection of oil cooler support panel and forward fanshaft support bracket:
(1) Remove aft fairing assembly in accordance with Task 2--1--28.1, TM 55--1520--248--23--1.
WARNING
S Naphtha/Naphthalene is combustible: do not use near welding area, flames, or on hot surface. Avoid
prolonged or repeated contact with liquid. Contact of skin with liquid can cause irritation. Inhalation of
vapors can cause irritation, giddiness, and drowsiness. If liquid contacts eyes; flush eyes thoroughly
with water. If there is prolonged skin contact, wash contacted area with soap and water. If vapors caose
dorwsiness, go to fresh air. Remove saturated clothing. If liquid is swallowed, do not try to vomit. In
all cases get immediate medical attention. When handling liquid in an air--exhausted partially covered
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