T83-25-51 R1: Rotor Head Horizontal Hinge Pins

T83-25-51 R1 BOEING VERTOL COMPANY: Amendment 39-4828 and Telegram issued June 11, 1984. Applies to Boeing Vertol Model 234 series helicopters certificated in all categories. Compliance is required as indicated. To prevent possible hazards in flight associated with cracking of the main rotor head horizontal hinge pins, accomplish the following: (a) Within the next 25 hours time in service from the effective date of this AD or before the accumulation of 1,600 hours time in service, whichever comes later, retire main rotor head horizontal hinge pins P/N's 114R2196-2, 114R2197-1, and 114R2197-5 and replace with serviceable parts. (b) An equivalent method of compliance with this AD may be used when approved by the Manager, New York Aircraft Certification Office, 181 South Franklin Avenue, Valley Stream, New York 11581. (c) In accordance with FAR 21.197 flight is permitted to a base where the requirements of this AD may be accomplished. (d) Within the next 50 hours time in service from the effective date of this AD revision or before the accumulation of 300 hours time in service, whichever comes later, retire main rotor head horizontal hinge pins that have serial numbers other than A-356 thru A-367, A- 380 thru A-403, A-440 and subsequent, and YZ-135 and subsequent, and replace with serviceable parts. Amendment 39-4828 became effective March 26, 1984, as to all persons except those persons to whom it was made immediately effective by telegraphic AD No. T83-25-51 issued December 9, 1983, which contained the amendment. This telegraphic revision becomes effective upon receipt.