60-07-02 BRANTLY: Amdt. 117 Part 507 Federal Register March 23, 1960. Applies to Model B-2 Helicopters.
Compliance required as indicated.
(a) Applies to Serial Numbers 1 through 31. Compliance required prior to next flight.
Failures of the tail rotor drive shaft through the cooling fan drive pulley bolt hole have occurred. These failures result in loss of directional control. To relieve stresses in this area and preclude recurrence of these failures, the tail rotor drive system must be modified to incorporate:
(1) New long tail rotor drive shaft P/N 108-31 incorporating 2 1/2-inch long plug pinned in forward end of shaft at support location for cooling fan drive pulley,
(2) Redesigned cooling fan drive pulley bearing support sleeve P/N 339-19,
(3) New cooling fan drive pulley P/N 339-4,
(4) New housing spacer P/N 339-18,
(5) New pin retainer P/N 339-17,
(6) New tail rotor shaft forward support bearing P/N 88505,
(7) New cooling fan attach bolt AN 173-14A with AN 960-10 washer and AN 365-1032 nut. (Brantly Service Bulletin No. 2 covers this same subject.)
Revised April 17, 1965.