70-14-02 BELL: Amendment 39-1023. Applies to all Bell Model 47D, 47D-1, 47G, 47G-2 and 47H-1 helicopters certificated in all categories, and to any other helicopters equipped with tail rotor hub assembly bolt (also called a blade grip retaining bolt or a bearing retaining bolt), P/N 47-641-052-3.
Compliance required as indicated.
To detect and prevent possible failure of the tail rotor hub assembly bolt due to a fatigue crack and to correct any improper installation of the hub bolt, accomplish the following:
(a) Within the next 50 hours time in service, remove and replace bolts with 550 hours or more total time in service on the effective date of this AD.
(b) Within the next 50 hours time in service, inspect, one time, bolts with less than 550 hours total time in service on the effective date of this AD as follows:
(1) Remove and disassemble the tail rotor assembly and remove the hub assembly bolts.
(2) Inspect the bolt head to shank radius for cracks using a magnetic particle or equivalent inspection method.
(3) Replace cracked bolts before further flight as specified in paragraph (e).
(c) Remove and replace bolts with less than 550 hours total time in service on the effective date of this AD at or prior to accumulating 600 hours total time in service.
(d) Remove and replace all replacement bolts at or prior to accumulating 600 hours total time in service.
(e) Install bolts in accordance with paragraph 6-16.e., Section VI, Model 47D-1, 47G and 47G-2 Maintenance and Overhaul Instruction Manual, as revised August 15, 1961, or in accordance with equivalent FAA approved procedures.
This amendment becomes effective August 10, 1970.