AD 79-10-09

79-10-09 HUGHES HELICOPTERS: Amendment 39-3466. Applies to Hughes Model 369D Helicopters certificated in all categories, except Serial Numbers 0409 and subsequent.

Compliance required as indicated.

To prevent failure of the tail rotor pitch control assembly, which could result in loss of tail rotor control, accomplish the following:

(a) Before further flight after the effective date of this AD, check the 369D21803-3 locknut and tang washer P/N MS172209 or HS1551S238 of the tail rotor pitch control assembly P/N 369D21800 as follows:

Pull back the non-rotating boot P/N 369D21806 from the tail rotor pitch control assembly P/N 369D21800 and check the locknut and tang washer by hand for looseness.

(1) If the locknut or tang washer is loose, remove and replace the tail rotor pitch control assembly with a serviceable assembly with a white dot on the locknut, before further flight.

(2) If either the locknut or tang washer is not loose, repeat the check forlooseness of the locknut or tang washer before each engine start-up. See (c) below for termination action.

The checks required by this AD may be performed by the pilot.

NOTE 1: For the requirements regarding the listing of compliance and method of compliance with this AD in the helicopter's permanent maintenance record, see FAR 91.173.

(b) For the operators that have previously complied with Hughes Service Information Notice DN-37, dated December 1, 1978, the following applies:

(1) If the tail rotor pitch control assembly was repaired due to looseness of the locknut or tang washer, repeat the checks in (a) above and remove and replace the tail rotor pitch control assembly within 150 hours time in service after the receipt of the airmail letter dated April 9, 1979.

(2) For the tail rotor pitch control assemblies for which records of repair are not known, see (b)(1) above.

(3) For the tail rotor pitch control assemblies which were repaired per DN- 37 with no looseness of the locknut or tang washer, the requirements of this AD do not apply.

NOTE 2: The pitch control assemblies which have loose locknut or tang washers must be overhauled per the Hughes Model 369D Helicopter Basic Handbook of Maintenance Instructions and DN-37, dated December 1, 1978, before return to service.

(c) For those assemblies which do not have loose tang washers or locknuts, per paragraph (a)(2) above, within 100 hours of time in service from the receipt of the airmail letter dated April 9, 1979, accomplish DN-37.

(d) Equivalent checks and repairs may be used when approved by the Chief, Aircraft Engineering Division, FAA Western Region.

This amendment becomes effective May 17, 1979, as to all persons except those persons to whom it was made immediately effective by the airmail letter dated April 9, 1979, which contained this amendment.