91-21-13 BOEING: Amendment 39-8060. Docket 91-NM-80-AD. Supersedes AD's 89-13-05 and 89-23-05. \n\n\tApplicability: Model 737-300, -400, and -500 series airplanes, listed in Boeing Service Bulletin 737-76-1023, dated February 14, 1991, certificated in any category. \n\n\tCompliance: Required as indicated, unless previously accomplished. \n\n\tTo minimize the potential for cable separation due to the Number 2 engine throttle cable chafing against the right wing front spar bracket, and to prevent Number 1 and Number 2 engine throttle control cable ratcheting feedback, accomplish the following: \n\n\tA.\tFor Model 737-300 series airplanes: Prior to the accumulation of 300 flight hours after July 24, 1989 (the effective date of Amendment 39-6240), unless previously accomplished within the previous 700 flight hours, and thereafter at intervals not to exceed 1,000 flight hours, gain access to the fuel shutoff cable pulley bracket near the right wing front spar station 124 and inspect thenumber two engine throttle cable for wear. Replace the cable, before further flight, if cable wear exceeds acceptable wear limits specified in Section 20-20-31 of the Model 737 Maintenance Manual. \n\n\tB.\tFor Model 737-400 series airplanes: Prior to the accumulation of 300 flight hours after November 27, 1989 (the effective date of Amendment 39-6367), unless previously accomplished within the previous 700 flight hours, and thereafter at intervals not to exceed 1,000 flight hours, gain access to the fuel shutoff cable pulley bracket near the right wing front spar station 124 and inspect the number two engine throttle cable for wear. Replace the cable, before further flight, if cable wear exceeds acceptable wear limits specified in Section 20-20-31 of the Model 737 Maintenance Manual. \n\n\tC.\tFor all airplanes: Within 36 months after the effective date of this AD, modify the engine throttle control cable system in accordance with Boeing Service Bulletin 737-76-1023, dated February 14, 1991. This modification constitutes terminating action for the repetitive inspections required by paragraphs A. and B. of this AD. \n\n\tD.\tAn 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, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. \n\n\tNOTE: The request should be forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Seattle ACO. \n\n\tE.\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD. \n\n\tF.\tThe inspections and modifications shall be done in accordance with Boeing Service Bulletin 737-76-1023, dated February 14, 1991. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124. Copies may be inspected at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington; or at the Office of the Federal Register, 1100 L Street NW., Room 8401, Washington, D.C. \n\n\tAirworthiness Directive 91-21-13 supersedes AD 89-13-05, Amendment 39-6240; and AD 89-23-05, Amendment 39-6367. \n\tThis amendment (39-8060, AD 91-21-13) becomes effective on November 29, 1991.