AD 75-11-11

75-11-11 SIKORSKY AIRCRAFT: Amendment 39-2217 as amended by Amendment 39-2432. Applies to all Sikorsky Aircraft Model S-64E and Model S-64F helicopters. To prevent failure of the torquemeter engine to gearbox shaft and gear assembly and consequent secondary damage to the main rotor control system components, remove prior to further flight, torquemeter engine to gearbox shaft and gear assemblies, P/N 6435-20564-042, with 3000 or more hours total time in service. Replace those assemblies removed with P/N 6435-20564-042 assemblies which have less than 3000 hours total time in service, or with P/N 6435-20564-044 assemblies, or with an equivalent approved by the Chief, Engineering and Manufacturing Branch, FAA, New England Region. All replacement P/N 6435-20564-042 assemblies must be removed prior to the accumulation of 3000 hours time in service.

Amendment 39-2217 became effective upon publication in the Federal Register for all persons except those to whom it was made effective immediately by telegram.

This amendment 39-2432 becomes effective December 2, 1975.