AD 78-25-04

78-25-04 HUGHES HELICOPTERS: Amendment 39-3364. Applies to Hughes Model 269A, TH-55A, 269A-1, 269B and 269C helicopters equipped with part number 269A5103-9 pinion assemblies, Hughes Tool Company, Serial Nos. 001 through 5101, certificated in all categories.

Compliance required as indicated, unless already accomplished.

To detect and prevent fatigue crack propagation that could cause failure of the main transmission input pinion assembly, accomplish the following:

(a) Within the next 50 hours additional time in service or 60 calendar days, whichever occurs first after the effective date of this AD, perform a magnetic particle inspection of all input pinions Part No. 269A5103-9, serial nos. listed in Table A, for cracks in accordance with the instructions of paragraph (d), Hughes Service Information Notice N-151.2, dated November 7, 1978. Reinspect these input pinions in accordance with paragraph (d) of the S.I.N. between 450 and 500 total hours time in service, if,at the time of the initial inspection, the assembly had less than 250 hours total time in service.

TABLE A

269A5103-9 Pinion Assembly Serial Nos. Affected by Paragraph (a) 164783 254498 164784 254500 164786 254501 164787 254502 164789 254504 164790 254506 164791 254508 164792 254509 164794 254510 164795 254511 164796 254512 164798 254513 164800 254514 164801 254515 164802 254516 164803 254517 164805 254518 164806 254519 164807 254520 164809 254521 164811 254522 164813 254524 164814 254525 164815 254526 164816 254527 164817 254528 164818 254529 164819 254532

254533

254534

254535

254536

254537

(b) Within 100 hours additional time in service after the effective date of this AD, perform a magnetic particle inspection of all other input pinions, Part No. 269A5103-9, for cracks, in accordance with the instructions of paragraph (d), Hughes Service Information Notice N-151.2, dated November 7, 1978.

(c) Prior to the installation of pinion assembly Part No. 269A5103-9 on any helicopter listed in this AD inspect per paragraph (d) of Hughes Service Information Notice No. N-151.2. Pinion assemblies of serial numbers listed in table A of paragraph (a) of this AD, which have less than 250 hours total time in service at time of inspection, must be reinspected per paragraph (d) of the above referenced S.I.N. after accumulating a total of 450 hours time in service and before accumulating 500 hours total time in service.

(d) Any assembly exhibiting crack indications as a result of those inspections performed in paragraphs (a), (b) and (c), above, must be removed from service and marked in a conspicuous manner to prevent inadvertent return to service.

NOTE 1: The agency recommends that all unserviceable pinion assemblies be returned to Hughes Helicopters Warranty and Repair Department. Reference: Paragraph d.2, Hughes Service InformationNotice No. N-151.2.

NOTE 2: Hughes Service Information Notice N-151.2, dated November 7, 1978, is the only version of the notice suitable for compliance with this AD.

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

(f) Special flight permits may be issued in accordance with FAR's 21.197 and 21.199 to operate aircraft to a base for the accomplishment of inspections required by this AD.

This amendment becomes effective December 18, 1978.