82-26-51 R1: Yoke Assemblies Service Time

82-26-51 R1 BELL HELICOPTER TEXTRON, INC.: Amendment 39-4760. Applies to Bell Helicopter Textron, Inc., Model 412 helicopters certificated in all categories that are equipped with main rotor yokes P/N 412-010-101-109, -113, -117, and -121. (Airworthiness Docket No. 82-ASW-82.) Compliance is required as indicated (unless already accomplished.) To prevent failure of the main rotor yoke, accomplish the following: (a) Effective immediately, the retirement life of yoke assemblies P/N 412-010-101- 113, -117, and -121 is reduced to 700 hours. Yokes with more than 675 hours time in service on the effective date of this AD may be operated an additional 25 hours maximum. (b) Install flex indicator kit, Bell P/N 412-703-006-101, on yoke assemblies P/N 412-010-101-113, -117, and -121 within 25 hours time in service after the effective date of this AD. Before the first flight of each day perform an inspection of the flex indicators and perform corrective action when deflection is indicated in accordance with the instructions in Bell Alert Service Bulletin 412-82-9, dated 12/9/82, or an equivalent procedure approved by the Manager, Aircraft Certification Division, Federal Aviation Administration, Southwest Region. (c) Before the first flight of each day perform a visual inspection of yoke assemblies P/N 412-010-101-109, -113, -117, and -121 in the area of the flexure concentrating on the area from the mast to the damper bridges including the transition radii from the flexure to the damper bridge mounting area, on both upper and lower surfaces of the yoke. (d) In accordance with FAR 21.197, flight is permitted to a base where the requirements of this AD may be accomplished. (e) Any equivalent means of compliance with this AD must be approved by the Manager, Aircraft Certification Division, Federal Aviation Administration, Southwest Region. NOTE: Refer to Bell Helicopter Textron, Inc., Service Bulletin 412-82-9, dated 12/9/82, or FAAapproved equivalent for flex indicator installation procedures. This amendment becomes effective December 2, 1983, as to all persons except those persons to whom it was made immediately effective by telegraphic AD T82-26-51 issued December 8, 1982, which contained this amendment.