AD 2000-20-20 Airworthiness Directives; Boeing Model 747-400 Series Airplanes

Models named: 747-400 series. Read the applicability below — it usually turns on serial or part numbers too.

Model 747-400 series airplanes, having line numbers 696 through 1187 inclusive, certificated in any category; equipped with Honeywell inertial reference units (IRU). 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 (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.

Required as indicated, unless accomplished previously. To prevent loss of multiple IRU's in flight, which could result in the loss of navigation data, and compromise the ability of the flight crew to maintain the safe flight and landing of the airplane, accomplish the following: Replacement (a) Within 18 months after the effective date of this AD, remove the left, center, and right IRU's, and install modified IRU's, in accordance with Boeing Alert Service Bulletin 747-34A2638, Revision 1, dated April 8, 1999. Note 2: Removal of existing left, center, and right IRU's and replacement with modified IRU's in accordance with Boeing Alert Service Bulletin 747-34A2638, dated January 29, 1999, is considered acceptable for compliance with paragraph (a) of this AD. Spares (b) As of the effective date of this AD, no person shall install an IRU having Boeing part number S242T101-110, S242T101-111, or S242T101-112, on any airplane. Alternative Methods of Compliance (c) 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. Operators shall submit their requests through an appropriate FAA Principal Avionics Inspector, who may add comments and then send it to the Manager, Seattle ACO. Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. Special Flight Permits (d) 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. Incorporation by Reference (e) The replacement shall be done in accordance with Boeing Alert Service Bulletin 747-34A2638, Revision 1, dated April 8, 1999. 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. (f) This amendment becomes effective on November 22, 2000. Issued in Renton, Washington, on October 6, 2000. Donald L. Riggin, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 00-26308 Filed 10-17-00; 8:45 am] BILLING CODE 4910-13-P