AD 99-25-13 C1

This document corrects two typographical errors that appeared in airworthiness directive (AD) 99-25-13 that applies to all Boeing Model 777-200 and -300 series airplanes. That AD currently requires revising the Limitations Section of the Airplane Flight Manual to prohibit the dispatch of certain airplanes under certain conditions. That AD 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 document corrects incorrect paragraph references. This correction is necessary to ensure that operators accomplish the appropriate requirements of the AD.

Final rule; correction.

99-25-13 C1 Boeing: Amendment 39-11456. Docket 99-NM-323-AD.\n\n\tApplicability: 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.\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 (f) 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.Compliance: Required as indicated, unless accomplished previously.\n \n\tTo 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:\n\nRevisions to the Airplane Flight Manual\n\n\t(a) For all airplanes: Within 14 days after the effective date of this AD, 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.\n\n\t"Dispatch of the airplane with an engine-mounted backup generator having a sheared shaft is prohibited.\n\n\tFollowing 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."\n\nProhibited Servicing or Replacement\n\n\t(b) For all airplanes: As of14 days after the effective date of this AD, 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.\n\nOne-Time Actions for Rolls-Royce Engines\n\n\t(c) For airplanes equipped with Rolls-Royce Trent 800 series turbofan engines: Within 14 days after the effective date of this AD, 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.\n\n\tNote 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.\n\nInspections and Corrective Actions\n\n\t(d) Within 14 days after the effective date of this AD, and thereafter prior to each flight: Accomplish paragraph (d)(1), (d)(2), or (d)(3) of this AD, as applicable.\n\nRolls-Royce Engines\n\n\t(1) For airplanes equipped with Rolls-Royce Trent 800 series turbofan engines, accomplish paragraphs (d)(1)(i) and (d)(1)(ii) of this AD.\n\n\t(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.\n\n\t(ii) 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, 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) or 2.a.(2), as applicable, in accordance with that service letter.\n\nGeneral Electric Engines\n\n\t(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) or 1.a.(2), as applicable, in accordance with the service letter.\n\nPratt & Whitney Engines\n\n\t(3) For Model 777 series airplanes equipped with Pratt & Whitney PW4000 series turbofan engines: If the status message "ELEC BACKUP GENL(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-24-025, dated August 18, 1999, in accordance with that service letter.\n\n\t(i) 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.\n\n\t(ii) 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.\n\nFlight Test After Replacement of Backup Generators\n\n (e) For all airplanes: 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 (e)(1) and (e)(2) of this AD at the times specified in those paragraphs.\n\n\t(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.\n\n\t(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 paragraph (d)(1), (d)(2), or (d)(3) of this AD, as applicable.\n\nAlternative Methods of Compliance\n\n\t(f) 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.\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(g) Special 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(h) Except as provided by paragraphs (a) and (d)(3)(i) of this AD, the actions shall be done in accordance with Rolls-Royce Service Bulletin RB.211-72-C813, Revision 1, dated July 16, 1999; Boeing Service Letter 777-SL-24-023-B, dated August 16, 1999; Boeing Service Letter 777-SL-24-024, dated August 16, 1999; or Boeing Service Letter 777-SL-24-025, dated August 18, 1999; as applicable. This incorporation by reference was approved previously by the Director of the Federal Register as of December 23, 1999 (64 FR 68618, December 8, 1999). 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 (i) The effective date of this amendment remains December 23, 1999.

Airworthiness Directive (AD) 99-25-13, amendment 39-11456, applicable to all Boeing Model 777-200 and -300 series airplanes, was published in the Federal Register on December 8, 1999 (64 FR 68618). That AD requires revising the Limitations Section of the Airplane Flight Manual to prohibit the dispatch of certain airplanes under certain conditions. That AD 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. That AD was prompted by reports of inflight shutdowns due to sheared backup generator shafts. The actions specified by that 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.\n\nNeed for the Correction\n\n\tInformation obtained recently by the FAA indicates that paragraph (e) of AD 99-25-13 contains two typographical errors. That paragraph specifies "paragraphs (c)(1) and (c)(2)" as the appropriate paragraph references for the action required after replacement of the backup generators.\n\n\tThe FAA has determined that a correction to AD 99-25-13 is necessary. The correction to paragraph (e) of that AD will specify "paragraphs (e)(1) and (e)(2)" as the appropriate paragraph references.\n\nCorrection of Publication\n\n\tThis document corrects the errors and correctly adds the AD as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13).\n\n\tThe AD is reprinted in its entirety for the convenience of affected operators. The effective date of the AD remains December 23, 1999.\n\n\tSince this action only corrects typographical errors, it has no adverse economic impact and imposes no additional burden on any person. Therefore, the FAA has determined that notice and public procedures are unnecessary.\n\nList of Subjects in 14 CFR Part 39\n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.\n\nAdoption of the Correction\n\n\tAccordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:\n\nPART 39-AIRWORTHINESS DIRECTIVES\n\n\t1. The authority citation for part 39 continues to read as follows:\n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701.\n\nSec. 39.13 (Corrected)\n\n\t2. Section 39.13 is amended by correctly adding the following airworthiness directive (AD):