Airworthiness Directive · Amendment 39-11833 · Boeing Model 747-200 and -300 Series Airplanes Equipped with General Electric CF6-80C2 Series Engines
Boeing Model 747-200 and -300 Series Airplanes Equipped with General Electric CF6-80C2 Series Engines
Model 747-200 and -300 series airplanes equipped with General Electric Model CF6-80C2 series engines with Power Management Control engine controls, certificated in any category.
Note 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 (h)(1) 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.
This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 747-200 and -300 series airplanes, that currently requires various inspections and functional tests to detect discrepancies of the thrust reverser control and indication system, and correction of any discrepancy found. This amendment requires installation of a terminating modification, and repetitive functional tests of that installation, and repair, if necessary. This amendment is prompted by the results of a safety review of the thrust reverser systems on Model 747 series airplanes. The actions specified by this AD are intended to ensure the integrity of the fail safe features of the thrust reverser system by preventing possible failure modes in the thrust reverser control system that can result in inadvertent deployment of a thrust reverser during flight.
To ensure the integrity of the fail safe features of the thrust reverser system by preventing possible failure modes in the thrust reverser control system that can result in inadvertent deployment of a thrust reverser during flight, accomplish the following:
(a) Within 90 days after April 13, 1995 (the effective date of AD 95-06-01, amendment 39-9171), perform tests of the position switch module and the cone brake of the center drive unit (CDU) on each thrust reverser, and perform an inspection to detect damage to the bullnose seal on the translating sleeve on each thrust reverser, in accordance with paragraphs III.A. through III.C. of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-78A2130, dated May 26, 1994. Repeat the tests and inspection thereafter at intervals not to exceed 1,000 hours time-in-service until the functional test required by paragraph (d) of this AD is accomplished.
(b) Within 9 months after April 13, 1995, perform inspections and functional tests of the thrust reverser control and indication system in accordance with paragraphs III.D. through III.F., III.H., and III.I. of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-78A2130, dated May 26, 1994. Repeat these inspections and functional tests thereafter at intervals not to exceed 18 months.
(c) If any of the inspections and/or functional tests required by paragraphs (a) and (b) of this AD cannot be successfully performed, or if any discrepancy is found during those inspections and/or functional tests, accomplish either paragraph (c)(1) or (c)(2) of this AD.
(1) Prior to further flight, correct the discrepancy found, in accordance with Boeing Alert Service Bulletin 747-78A2130, dated May 26, 1994. Or
(2) The airplane may be operated in accordance with the provisions and limitations specified in an operator's FAA-approved Minimum Equipment List (MEL), provided that no more than one thrust reverser on the airplane is inoperative.
(d) Within 1,000 hours time-in-service after the most recent test of the CDU cone brake performed in accordance with paragraph (a) of this AD, or within 650 hours time-in-service after August 25, 1999 (the effective date of AD 99-15-08, amendment 39-11227), whichever occurs first: Perform a functional test to detect discrepancies of the CDU cone brake on each thrust reverser, in accordance with Boeing Service Bulletin 747-78A2166, Revision 1, dated October 9, 1997, or paragraph III.B. of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-78A2130, dated May 26, 1994. Repeat the functional test thereafter at the interval specified in paragraph (d)(1) or (d)(2) of this AD, as applicable. Accomplishment of such functional test constitutes terminating action for the repetitive test of the CDU cone brake required by paragraph (a) of this AD; the position switch module tests and the bullnose seal inspections continue to be required as specified in paragraph (a) of this AD.
(1) For airplanes equipped with thrust reversers NOT modified in accordance with Boeing Service Bulletin 747-78-2144, Revision 1, dated April 11, 1996: Repeat the functional test at intervals not to exceed 650 hours time-in-service.
(2) For airplanes equipped with thrust reversers modified in accordance with Boeing Service Bulletin 747-78-2144, Revision 1, dated April 11, 1996: Repeat the functional test at intervals not to exceed 1,000 hours time-in-service.
(e) If any functional test required by paragraph (d) of this AD cannot be successfully performed, or if any discrepancy is found during any functional test required by paragraph (d) of this AD, accomplish either paragraph (e)(1) or (e)(2) of this AD.
(1) Prior to further flight, correct the discrepancy found, in accordance with Boeing Service Bulletin 747-78A2166, Revision 1, dated October 9, 1997, or paragraph III.B. of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-78A2130, dated May 26, 1994. Or
(2) The airplane may be operated in accordance with the provisions and limitations specified in the operator's FAA-approved MEL, provided that no more than one thrust reverser on the airplane is inoperative.
(f) Accomplish the requirements of paragraphs (f)(1) and (f)(2) of this AD at the times specified in those paragraphs. Accomplishment of the actions required by paragraph (f)(1) of this AD constitutes terminating action for the requirements of paragraphs (a), (b), (d), and (e) of this AD.
(1) Within 36 months after the effective date of this AD, accomplish the requirements of paragraphs (f)(1)(i) and (f)(1)(ii) of this AD.
(i) Install an actuation system lock bracket and fastening hardware to each thrust reverser in accordance with the Accomplishment Instructions of Lockheed Martin Service Bulletin 78-1007, Revision 1, dated March 18, 1997, or Middle River Aircraft Systems Service Bulletin 78-1007, Revision 2, dated March 10, 1998.
(ii) Install an actuation system lock (also called an electro-mechanical lock or electro-mechanical brake) on each thrust reverser in accordance with the Accomplishment Instructions of Lockheed Martin Service Bulletin 78-1020, Revision 2, dated March 20, 1997, or Middle River Aircraft Systems Service Bulletin 78-1020, Revision 3, dated March 16, 1998.
(2) Prior to or concurrent with the accomplishment of the requirements of paragraph (f)(1)(ii) of this AD, perform the thrust reverser wiring modifications of the wings, strut, and fuselage, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-78-2144, Revision 1, dated April 11, 1996.
(g) Within 1,000 hours time-in-service after accomplishment of paragraph (f) of this AD, or within 1,000 hours time-in-service after the effective date of this AD, whichever occurs later: Perform a functional test to detect discrepancies of the CDU cone brake and actuation system lock on each thrust reverser, in accordance with Appendix 1 of this AD. Prior to further flight, correct any discrepancy detected and repeat the functional test of that repair, in accordance with the procedures described in the Boeing 747 Maintenance Manual. Repeat the functional tests thereafter at intervals not to exceed 1,000 hours time-in-service.
(h)(1) An 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.
(2) Alternative methods of compliance, approved previously in accordance with AD 99-15-08, amendment 39-11227, are approved as alternative methods of compliance with the corresponding requirements specified in this AD.
Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.
