AD 59-16-04

59-16-04 SIKORSKY: Amendment 34 (24 F.R. 6581) as amended by Amendment 39-2140. Applies to all model S-58 helicopters including military types HSS-1, HSS-1F, HSS-1N, HUS-1, HUS-1A, HUS-1AN, HUS-1G, HUS-1Z, H-34A, H-34C, H-34J, CH-34A, CH-34C, HH-34F, SH-34G, SH-34H, SH-34J, UH-34D, UH-34E, UH-34G, UH-34J, VH-34C, VH-34D, except for those modified in accordance with Sikorsky Modification Kit, P/N S1607-5695-1.

Compliance required as indicated.

Due to the present design of the damper trunnion assembly, torque cannot be maintained on the bolt, thereby leading to fretting and fatiguing of the bolt. Although this problem has been partially corrected by replacing the AN 177-34 bolt with S1610-23198 bolt (NAS 627-48 bolt with cotter pin hole), working of the bolt in the assembly has not been completely eliminated. Accordingly, it is considered essential that close surveillance be maintained and the following inspection be carried out pending the development and installation of aredesigned trunnion assembly to correct this difficulty.

During the 50-hour periodic inspection of the damper trunnion for freedom per item No. 20(c) of the Periodic Inspection Check Sheet, Airframe System S-58 Maintenance Manual, remove the damper trunnion bolt P/N S1610-23198 and inspect for condition. If indications of wearing, scouring or fretting are found the bolt must be replaced prior to further flight.

This amendment 39-2140 becomes effective April 8, 1975.