61-04-01: Clutch Bolts

61-04-01 BRANTLY: Amdt. 252 Part 507 Federal Register February 10, 1961. Applies to All B-2 Helicopters. Compliance required as indicated. Instances have occurred wherein the centrifugal clutch has failed to release at engine shutdown and subsequent restarting has sheared the bolts which transmit torque from the B2-8-14 clutch disc assembly into the fabric coupling and from the fabric coupling into the lugs of the free-wheeling clutch housing. To preclude recurrence of this condition the following must be accomplished: (a) Within the next 10 hours of flight time after the effective date of this directive, inspect all 6 of the AN 4-10A bolts which secure the fabric coupling to the B2-8-14 clutch disc assembly and to the free-wheeling clutch housing for shear failure. This inspection is to be accomplished by inserting an appropriately sized wrench through the lubrication access hole in the B2-7-17 clutch dust cover and checking each bolt for snugness. Any sheared bolts must be replaced prior to further operation. (b) Within the next 10 hours of flight time after the effective date of this directive a placard shall be installed immediately aft or incorporated with the operating limitations placard located between the fuel mixture control and the carburetor heat control levers to read: "PRIOR TO EACH ENGINE START, TURN ROTOR BACKWARD BY HAND THROUGH 30 DEGREES MINIMUM TO CHECK CLUTCH FREEDOM." The purpose of this placard is to insure that these coupling bolts are not subjected to damage resulting from failure of the clutch to release. (Brantly Service Bulletin No. 6 covers this same subject.) This directive effective February 22, 1961.