Airworthiness Directive · Amendment 39-11502 · Boeing Model 747 Series Airplanes
Boeing Model 747 Series Airplanes
Model 747-100B, -200, -300, and SP series airplanes, equipped with Rolls Royce RB211-524B2, C2, and D4 engines; certificated in any category, as listed in the following service bulletins:
Boeing Alert Service Bulletin 747-78A2148, dated June 1, 1995;
Boeing Service Bulletin 747-78A2148, Revision 1, dated July 20, 1995;
Boeing Service Bulletin 747-78-2136, dated May 11, 1995; and
Boeing Service Bulletin 747-78-2156, dated October 31, 1996.
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 series airplanes. That AD currently requires repetitive inspections and tests of the thrust reverser control and indication system on each engine, and corrective actions, if necessary; installation of a terminating modification; and repetitive operational checks of that installation, and repair, if necessary. This amendment is prompted by the results of a safety review, which revealed that in-flight deployment of a thrust reverser could result in significant reduction in airplane controllability. The actions specified in this AD are intended to ensure the integrity of the fail-safe features of the thrust reverser system by preventing possible failure modes, which could result in inadvertent deployment of a thrust reverser during flight, and consequent reduced controllability of the airplane. This action identifies certain repetitive operational checks that were inadvertently omitted from the existing AD, and revises certain procedures for accomplishment of the operational checks and certain follow-on corrective actions.
Required as indicated, unless accomplished previously.
To prevent inadvertent deployment of a thrust reverser during flight and consequent reduced controllability of the airplane, accomplish the following:
Restatement of Requirements of AD 99-18-03
Repetitive Inspections and Tests
(a) Within 90 days after September 15, 1999 (the effective date of AD 99-18-03, amendment 39-11269): Perform the applicable inspections and tests of the thrust reverser control and indication system on each engine, in accordance with Part III.A. through III.G. of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-78A2148, dated June 1, 1995, or Boeing Service Bulletin 747-78A2148, Revision 1, dated July 20, 1995. Repeat the applicable inspections and tests thereafter at intervals not to exceed 18 months, until accomplishment of paragraph (c) of this AD.
Corrective Actions
(b) If any inspection or test required by paragraph (a) of this AD cannot be successfully performed as specified in the service bulletin, or if any discrepancy is detected during any inspection or test, prior to further flight, repair in accordance with Boeing Alert Service Bulletin 747-78A2148, dated June 1, 1995, or Boeing Service Bulletin 747-78A2148, Revision 1, dated July 20, 1995. Additionally, prior to further flight, any failed inspection or test required by paragraph (a) of this AD must be repeated and successfully accomplished.
Modification
(c) Within 36 months after September 15, 1999: Install an additional locking system on the thrust reversers in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-78-2156, dated October 31, 1996. Prior to or concurrent with accomplishment of Boeing Service Bulletin 747-78-2156, dated October 31, 1996: Accomplish Boeing Service Bulletin 747-78-2136, dated May 11, 1995; and Rolls-Royce Service Bulletins RB.211-71-B545, Revision 2, dated August 8, 1997, RB.211-71-B551, Revision 1, dated March 20, 1998, and RB.211-78-B552, dated June 21, 1996.
Accomplishment of these actions constitutes terminating action for the repetitive inspections and tests required by paragraph (a) of this AD.
Operational Checks
(d) Within 3,000 flight hours after accomplishing the modification required by paragraph (c) of this AD, or within 1,000 flight hours after September 15, 1999, whichever occurs later: Perform operational checks of the number 2 and number 3 gearbox locks and of the air motor brake, in accordance with the procedures described in Appendix 1 (including Figure 1) of this AD. Repeat the operational checks thereafter at intervals not to exceed 3,000 flight hours.
Corrective Actions
(e) If any operational check required by paragraph (d) of this AD cannot be successfully performed as specified in the procedures described in Appendix 1 (including Figure 1) of this AD, or, if any discrepancy is detected during any operational check, prior to further flight, repair in accordance with the procedures specified in the Boeing 747 Airplane Maintenance Manual. Additionally, prior to further flight, any failed operational check required by paragraph (d) of this AD must be repeated and successfully accomplished. Continue to repeat the operational checks thereafter at intervals not to exceed 3,000 flight hours.
