76-19-03 HUGHES HELICOPTERS: Amendment 39-2725. Applies to Hughes Model 369H, 369HS, 369HE and 369HM helicopters, certificated in all categories, equipped with shock mounted stabilizer strut assembly P/N 369A2001-601.
Compliance required as indicated unless already accomplished.
To prevent fatigue failures of the damper plunger which could result in the loss of the stabilizer strut and possible contact with the tail rotor, accomplish the following:
(a) Within 25 hours time in service after the effective date of this AD, disassemble the stabilizer strut P/N 369A2001-601 and determine if the damper plunger P/N 369A2130 or P/N 369A2130-3 has cut threads in accordance with Hughes Service Information Notice HN102.1 dated August 25, 1976 or later FAA-approved revision.
(b) If the damper plunger is found to have cut threads during the inspection required by paragraph (a), before further flight, either replace the damper plunger with a damper plunger with rolled threads, or inspect the threaded area for cracks using the dye penetrant or magnetic particle inspection method.
(1) If cracks are found, before further flight, replace the damper plunger with a damper plunger, P/N 369A2130 or P/N 369A2130-3, with rolled threads.
(2) If cracks are not found, within 100 hours additional time in service after the inspection required by paragraph (a), replace the damper plunger with a damper plunger, P/N 369A2130 or P/N 369A2130-3, with rolled threads.
(c) Equivalent inspection methods or alternate replacement parts may be used when approved by the Chief, Aircraft Engineering Division, FAA Western Region.
(d) Special flight permits may be issued in accordance with FAR's 21.197 and 21.199 to operate helicopters to a base for the accomplishment of the inspections required by this AD.
This amendment becomes effective September 24, 1976.