Airworthiness Directive · Amendment 39-11803 · Boeing Model 777-200 and -300 Series Airplanes
Boeing Model 777-200 and -300 Series Airplanes
Model 777-200 and -300 series airplanes equipped with Rolls-Royce Trent 800, General Electric GE90, or Pratt & Whitney PW4000 series turbofan engines; 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) 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 all Boeing Model 777-200 and -300 series airplanes, that currently requires revising the Limitations Section of the Airplane Flight Manual (AFM) to prohibit the dispatch of certain airplanes under certain conditions. That amendment also requires repetitive inspections to ensure correct operation of the backup generators; and, for certain airplanes, a one-time inspection to detect damage of the engine external gearbox; and corrective actions, if necessary. This amendment continues the AFM and inspection requirements and expands certain corrective action requirements. This amendment is prompted by reports of inflight shutdowns due to sheared backup generator shafts. The actions specified in this AD are intended to prohibit the dispatch of an airplane with an engine-mounted backup generator having a sheared shaft; and to detect and correct damage to the engine, which could result in inflight shutdowns.
To prohibit dispatch of an airplane with an engine-mounted backup generator having a sheared shaft; and to detect and correct damage to the engine, which could result in inflight shutdowns; accomplish the following:
(a) For all airplanes: Within 14 days after December 23, 1999 (the effective date of AD 99-25-13 C1, amendment 39-11456), revise the Limitations Section of the FAA-approved Airplane Flight Manual (AFM) to include the following information. This may be accomplished by inserting a copy of this AD in the AFM.
Dispatch of the airplane with an engine-mounted backup generator having a sheared shaft is prohibited.
Following replacement of the backup generator on both the left and right engines, extended twin-engine operations (ETOPS) flight is prohibited until a non-ETOPS flight of at least one hour in duration is accomplished.
(b) For all airplanes: As of 14 days after December 23, 1999, the servicing of both the left and right backup generators or replacement of both backup generators with new or serviceable components by the same individual prior to the same flight is prohibited.
(c) For airplanes equipped with Rolls-Royce Trent 800 series turbofan engines: Within 14 days after December 23, 1999, determine whether the status message “ELEC BACKUP GEN L(R)” and the maintenance message “Backup generator L(R) has a sheared shaft” have occurred within the last 250 flight hours prior to the effective date of this AD. If these messages have occurred during that time, accomplish follow-on corrective actions, as applicable, at the times specified in paragraphs C.1.(c) and D. of Rolls-Royce Service Bulletin RB.211-72-C813, Revision 1, dated July 16, 1999, in accordance with the procedures specified in the service bulletin.
Note 2: Boeing Service Letter 777-SL-24-023-B, dated August 16, 1999, references Rolls-Royce Service Bulletin RB.211-72-C813, Revision 1, dated July 16, 1999, as an additional source of service information to accomplish certain actions required by this AD.
Inspections and Corrective Actions: Pratt & Whitney Engines
(d) For Model 777 series airplanes equipped with Pratt & Whitney PW4000 series turbofan engines: Within 14 days after December 23, 1999, and thereafter prior to each flight, if the status message “ELEC BACKUP GEN L(R)” is active, prior to further flight, inspect the Maintenance Access Terminal (MAT) for certain maintenance messages indicating a sheared shaft or low oil pressure, in accordance with Step 1.a. of Boeing Service Letter 777-SL-24-025, dated August 18, 1999.
(1) If any of the specified maintenance messages is active, prior to further flight, remove and replace the backup generator in accordance with Airplane Maintenance Manual (AMM) 24-25-01-000-801 or 24-25-01-400-801, as applicable.
(2) If the backup generator shaft is found to be sheared, or either of the low oil pressure messages are active, prior to further flight, accomplish the corrective actions specified in Step 1.a.(1) of Boeing Service Letter 777-SL-24-025, dated August 18, 1999, in accordance with that service letter.
(e) For airplanes equipped with Pratt & Whitney PW4000 series turbofan engines: As of 14 days after December 23, 1999, following any replacement of the backup generator on both the left and right engines, accomplish paragraphs (e)(1) and (e)(2) of this AD at the times specified in those paragraphs.
(1) Prior to any ETOPS flight, conduct a non-revenue test flight of at least one hour in duration, or a non-ETOPS flight that is either a non-revenue or revenue flight of at least one hour in duration.
(2) Prior to further flight after accomplishment of the action required by paragraph (e)(1) of this AD: Verify accomplishment of the maintenance actions required by paragraphs (d), (d)(1), and (d)(2) of this AD, as applicable.
(f) Within 14 days after the effective date of this AD, and thereafter prior to each flight: Accomplish paragraphs (f)(1) or (f)(2) of this AD, as applicable.
(1) For airplanes equipped with Rolls-Royce Trent 800 series turbofan engines: Accomplish paragraphs (f)(1)(i) and (f)(1)(ii) of this AD.
(i) Inspect the Electrical Maintenance Page of the engine indicating and crew alerting system (EICAS), and perform follow-on corrective actions, as applicable, at the times specified in and in accordance with the procedures specified in Boeing Service Letter 777-SL-24-023-B, dated August 16, 1999.
(ii) If the status message “ELEC BACKUP GEN L(R)” is active: Prior to further flight, inspect the MAT for certain maintenance messages indicating a sheared shaft or low oil pressure, as specified in Step 2.a. of Boeing Service Letter 777-SL-24-023-B, dated August 16, 1999; and accomplish the corrective actions specified in Steps 2.a.(1) and 2.a.(2) of the service letter, as applicable, in accordance with that service letter.
(2) For airplanes equipped with General Electric GE90 series turbofan engines: If the status message “ELEC BACKUP GEN L(R)” is active, prior to further flight, inspect the MAT for certain maintenance messages indicating a sheared shaft or low oil pressure, as specified in Step 1.a. of Boeing Service Letter 777-SL-24-024, dated August 16, 1999; and accomplish the corrective actions specified in Steps 1.a.(1) and 1.a.(2) of the service letter, as applicable, in accordance with the service letter.
(g) For airplanes equipped with Rolls-Royce Trent 800 and General Electric GE90 series turbofan engines: As of 14 days after the effective date of this AD, following any replacement of the backup generator on both the left and right engines, accomplish paragraphs (g)(1) and (g)(2) of this AD at the times specified in those paragraphs.
(1) Prior to any ETOPS flight, conduct a non-revenue test flight of at least one hour in duration, or a non-ETOPS flight that is either a non-revenue or revenue flight of at least one hour in duration.
(2) Prior to further flight after accomplishment of the action required by paragraph (g)(1) of this AD: Verify accomplishment of the maintenance actions required by paragraph (f)(1) or (f)(2) of this AD, as applicable.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Aircraft
