52-01-05 BELL: Applies to All Models 47B and 47B3 Helicopters and to Model 47D Helicopters Serial Numbers 1 to 110, Inclusive.
Compliance required at next 300-hour overhaul, but not later than March 1, 1952.
To provide a tail rotor blade grip retaining bolt of increased service life, replace each existing 47-641-026-1 bolt with the 47-641-052-1 bolt, and torque to 160-190 inch-pounds. Also, replace the 47-641-036-1 flat washer type micarta seal in the blade yoke on Models 47B and 47B3 helicopters with the 47-641-042-1 cup seal type.
(Bell Service Bulletin No. 80 covers this same subject.)