78-16-02 R1 DOWTY ROTOL LTD: Amendment 39-3272 as amended by Amendment 39-4946. Applies to Dowty Rotol Type R.209/4-40-4.5/2 propellers installed on Nihon Model YS-11 and YS-11A airplanes. Compliance is required as indicated unless already accomplished.
To reduce the possibility of propeller hub failure due to cracks in the hub arm threads and subsequent loss of propeller blade retention, accomplish the following:
(a) On propellers which have accumulated 10,000 flight cycles or more, within the next 1,000 flight cycles after the effective date of this AD or at a time not to exceed 3,000 flight cycles since the previous inspection for cracks, whichever occurs first, inspect the propeller hub (arm) blade bearing retaining threads for cracks in accordance with Dowty Rotol Service Bulletin 61-890 dated July 11, 1977, or an FAA-approved equivalent (hereinafter referred to as Service Bulletin). In addition -
(1) If, during any inspection conducted after the effective date of this AD propeller hub cracking is found, before further operation, replace the propeller hub with a serviceable hub of the same part number; and
(2) Handle defective hubs in accordance with paragraph 1.C(4) of the Service Bulletin.
(3) Compliance with this AD is not required for propellers having the new strengthened hub Part No. 601023446 installed in place of hub Part No. 601023335.
(b) For purposes of this AD a flight cycle is defined as a flight operation involving one takeoff and landing. For purposes of complying with this AD, when the number of flight cycles cannot be determined from propeller/airplane records, subject to acceptance by the assigned FAA maintenance inspector, the number of flight cycles may be determined by equating one flight cycle to 1/2 hour time in service.
(c) If during the inspection required by paragraph (a) of this AD, or at any subsequent inspection, propeller hub cracking is detected, inspect all the operator's propellers covered by this AD, which have accumulated more than 10,000 flight cycles, in accordance with paragraph (a) within 1,000 flight cycles of the detection of the cracks, and, thereafter, at intervals not to exceed 3,000 flight cycles.
(d) Airplanes may be flown in accordance with the provisions of FAR Sections 21.197 and 21.199 to a base where the inspections and parts replacement required by this AD can be accomplished.
(e) Upon request, the Manager, Engine and Propeller Standards Staff, ANE-110, FAA, New England Region, may adjust the inspection interval.
Amendment 39-3272 became effective August 28, 1978.
This Amendment 39-4946 becomes effective on November 15, 1984.