82-16-07 HILLER AVIATION: Amendment 39-4469. Applies to Hiller Aviation Model UH-12E and L and OH-23F and G Series helicopters certificated in all categories that are equipped with engine drive torsional coupling assemblies, P/N 21047-9 and P/N 21047-11 (S/N 704 through 766) and P/N 21047-15 (all serial numbers), Airworthiness Docket No. 82-ASW-52. Compliance required as indicated unless already accomplished.
To detect possible cracks and prevent failure of the engine drive torsional coupling assembly, accomplish the following:
1. Within 10 hours' time in service after the effective date of this AD and thereafter at intervals not to exceed 50 hours' time in service:
(a) Remove from the helicopter torsional coupling assemblies P/N 21047-9 and -11 (S/N 704 through 766) and P/N 21047-15 (all serial numbers). These have a stamped rubber cure date of December 1980 or later.
(b) Clean and inspect the lower housing P/N 21046 in the eight window areas adjacent to the engine attach flange using a fluorescent penetrant inspection method.
(c) Replace assemblies with cracked housings before further flight and install a serviceable assembly as prescribed in the appropriate model maintenance manual or FAA approved equivalent.
2. The inspections required by this AD are not applicable to UH-12E, or OH-23F and G series helicopters converted to the turbine engine installation by STC SH178WE.
3. Equivalent means of compliance must be approved by the Manager, Western Aircraft Certification Field Office, P.O. Box 92007, World Way Postal Center, Los Angeles, California 90009.
4. Special flight permits may be issued in accordance with FAR 21.197 and FAR 21.199 to fly aircraft to a base where compliance with this AD can be accomplished.
Hiller Aviation Service Bulletin S.B. UH-12-21-3 dated August 4, 1982, contains information regarding this AD.
This amendment becomes effective October 15, 1982, to all persons, except those to whomit was made immediately effective by priority mail AD 82-16-07 issued July 23, 1982.