74-17-07 ENSTROM: Amendment 39-1925. Applies to the following Enstrom Model F- 28A main rotor gearboxes, Serial Numbers: 03A, 016, 025, 041, 050, 063, 073, 082, 09-02-69, 08-001-72, and 20-001-72.
Compliance required as indicated unless already accomplished:
(a) All main rotor gearboxes in this group with a total time since remanufacture of 100 hours or more must be returned to the Enstrom facility for teardown and inspection within the next 5 hours.
(b) All main rotor gearboxes in this group with a total time since remanufacture of less than 100 hours should be returned to the Enstrom facility for teardown and inspection before accumulating 100 hours.
This amendment becomes effective August 24, 1974.