93-05-01: Main Rotor Yoke Assembly

93-05-01 BELL HELICOPTER TEXTRON, INC. (BHTI): Amendment 39-8507. Docket Number 92-ASW-13. Applicability: BHTI Model 212 helicopters, certificated in any category. Compliance: Required as indicated, unless accomplished previously. To prevent possible fatigue failure of the main rotor yoke assembly, accomplish the following: (a) For main rotor hub assemblies with main rotor yokes, part number (P/N) 204- 011-102 (all dash numbers), having 1,100 or more hours time in service since new or the last overhaul on the effective date of this AD, perform the following within the next 100 hours time in service, and thereafter at intervals not to exceed 1,200 hours time in service: (1) Remove the main rotor yoke from the hub assembly. Visually inspect the pillow block bushing holes for corrosion and mechanical damage. Inspect the yoke for cracks using the magnetic particle method as specified in the BHTI component repair and overhaul manual. (2) If cracks are found, or if corrosion or mechanical damage is present that cannot be removed within the rework limits of the BHTI component repair and overhaul manual, replace the main rotor yoke with an airworthy part. (b) For main rotor hub assemblies with main rotor yokes, P/N 204-011-102 (all dash numbers), having less than 1,100 hours time in service since new or the last overhaul on the effective date of this AD, comply with paragraphs (a)(1) and (2) of this AD prior to attaining 1,200 hours time in service, and thereafter at intervals not to exceed 1,200 hours time in service from the last inspection. (c) If no cracks are found and the yoke is airworthy, reinstall it in accordance with the BHTI component repair and overhaul manual. (d) An alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Rotorcraft Certification Office, ASW-170, FAA, 4400 Blue Mound Road, Fort Worth, Texas 76106. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Rotorcraft Certification Office. NOTE: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Manager, Rotorcraft Certification Office. (e) The visual and magnetic particle inspection specified in BHTI, Alert Service Bulletin 212-90-60, Part III, dated March 23, 1990, is an equivalent means of compliance with this AD. (f) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the helicopter to a location where the requirements of this AD can be accomplished. (g) This amendment becomes effective on April 19, 1993.