99-21-18: Thrust Control Cable

99-21-18 BOEING: Amendment 39-11363. Docket 98-NM-363-AD. \n\n\tApplicability: Model 767 series airplanes powered by Pratt & Whitney JT9D-7R4 series turbofan engines or General Electric CF6-80A series turbofan engines, certificated in any category. \n\n\tNOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent engine thrust control cable failure, which could result in a severe asymmetric thrust condition during landing, and consequent reduced controllability of the airplane, accomplish the following: \n\n\t(a)\tFor all airplanes: Within 18 months or 4,500 flight hours after the effective date of this AD, whichever occurs first, accomplish the "Thrust Control Cable Inspection Procedure" specified in Appendix 1. (including Figure 1) of this AD to verify the integrity of the thrust control cables. Prior to further flight, repair any discrepancy found, in accordance with the procedures described in the Boeing 767 Maintenance Manual. Repeat the inspection thereafter at intervals not to exceed 18 months or 4,500 flight hours, whichever occurs first. \n\n\t(b)\tFor airplanes identified in Boeing Service Bulletin 767-76-0010, Revision 1, dated February 20, 1992: Within 18 months or 4,500 flight hours after the effectivedate of this AD, whichever occurs first, replace the two non-metallic pulleys of the thrust control cable that are located in the leading edge of the wing adjacent to the left and right engine strut with aluminum pulleys; and re-rig the thrust control cables; in accordance with the service bulletin. \n\n\tNOTE 2: Accomplishment of the replacement specified in Boeing Service Bulletin 767-76-0010, dated April 19, 1985, is acceptable for compliance with the replacement required by paragraph (b) of this AD. \n\nAlternative Methods of Compliance \n\n\t(c)\tAn alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO. \n\n\tNOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\nSpecial Flight Permits \n\n\t(d)\tSpecial flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. \n\nIncorporation by Reference \n\n\t(e)\tThe replacement and re-rigging specified in paragraph (b) of this AD shall be done in accordance with Boeing Service Bulletin 767-76-0010, Revision 1, dated February 20, 1992. 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 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\n\t(f)\tThis amendment becomes effective on November 22, 1999. \n\n\t\t\t\t\tAPPENDIX 1. \n\n\t\t\t\tTHRUST CONTROL CABLE \n\t\t\t\tINSPECTION PROCEDURE \n\n1.\tGeneral \n\n\tA.\tClean the cables, if necessary, for the inspection, in accordance with Boeing 767 Maintenance Manual 12-21-31. \n\n\tB.\tUse these procedures to verify the integrity of the thrust control cable system. The procedures must be performed along the entire cable run for each engine. To ensure verification of the portions of the cables which are in contact with pulleys and quadrants, the thrust control must be moved by operation of the thrust and/or the reverse thrust levers to expose those portions of the cables. \n\n\tC.\tThe first task is an inspection of the control cable wire rope. The second task is an inspection of the control cable fittings. The third task is an inspection of the pulleys. \n\nNote: These three tasks may be performed concurrently at one location of the cable system on the airplane, if desired, for convenience. \n\nNote: For the purposes of this procedure, a detailed visual inspection is defined as: "An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required." \n\n2.\tInspection of the Control Cable Wire Rope \n\n\tA.\tPerform a detailed visual inspection to ensure that the cable does not contact parts other than pulleys, quadrants, cable seals, or grommets installed to control the cable routing. Look for evidence of contact with other parts. Correct the condition if evidence of contact is found. \n\n\tB.\tPerform a detailed visual inspection of the cable runs to detect incorrect routing, kinks in the wire rope, or other damage. Replace the cable assembly if: \n\n\t\t(1)\tOne cable strand had worn wires where one wire cross section is decreased by more than 40 percent (see Figure 1), \n\n\t\t(2)\tA kink is found, or \n\n\t\t(3)\tCorrosion is found. \n\n\tC.\tPerform a detailed visual inspection of the cable: To check for broken wires, rub a cloth along the length of the cable. The cloth catches on broken wires. \n\n\t\t(1)\tReplace the 7x7 cable assembly if there are two or more broken wires in 12 continuous inches of cable or there are three or more broken wires anywhere in the total cable assembly. \n\n\t\t(2)\tReplace the 7x19 cable assembly if there are four or more broken wires in 12 continuous inches of cable or there are six or more broken wires anywhere in the total cable assembly. \n\n3.\tInspection of the Control Cable Fittings \n\n\tA.\tPerform a detailed visual inspection to ensure that the means of locking the joints are intact (wire locking, cotter pins, turnbuckle clips, etc.). Install any missing parts. \n\n\tB.\tPerform a detailed visual inspection of the swaged portions of swaged end fitting to detect surface cracks or corrosion. Replace the cable assembly if cracks or corrosion are found. \n\n\tC.\tPerform a detailed visual inspection of the unswaged portion of the end fitting. Replace the cable assembly if a crack is visible, if corrosion is present, or if the end fitting is bent more than 2 degrees. \n\n\tD.\tPerform a detailed visual inspection of the turnbuckle. Replace the turnbuckle if a crack is visible or if corrosion is present. \n\n4.\tInspection of Pulleys \n\tA.\tPerform a detailed visual inspection to ensure that pulleys are free to rotate. Replace pulleys which are not free to rotate.