Remarks: The compliance of this AD must be recorded in Aircraft Logbook, where applicable the requirements of this AD must be integrated into Aircraft Technical Documentation. Address inquiries concerning this AD to: Civil Aviation Authority, Airworthiness Division, Ruzyne Airport, 160 08 Prague 6, Czech Republic, tel: 420 2 33320922, fax: 420 2 20562270.

2000-26-05 BOEING: Amendment 39-12055. Docket 2000-NM-226-AD.

Applicability: Model 737-300, 737-400, 737–500, 747, 757-200, 757-300, 767-200, 767-300, and 767-300F series airplanes, certificated in any category, having the line numbers listed in the following table:

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 (b) 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.

To prevent potential ignition of fiberglass insulation in the environmental control system (ECS) ducts, which could propagate a small fire and lead to a larger fire, accomplish the following:

(a) Within 6 years after the effective date of this AD, rework ECS duct assemblies or replace existing duct assemblies with new or reworked duct assemblies, in accordance with Boeing Alert Service Bulletins 737-21A1129, 747-21A2416, 757-21A0084, 757-21A0085, or 767-21A0158; all including Appendices A and B; all dated June 29, 2000; as applicable.

Alternative Methods of Compliance
(b) 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 Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

NOTE 2: 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
(c) 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.

(d) The actions shall be done in accordance with Boeing Alert Service Bulletin 737-21A1129, including Appendices A and B; dated June 29, 2000; Boeing Alert Service Bulletin 747-21A2416, including Appendices A and B; dated June 29, 2000; Boeing Alert Service Bulletin 757-21A0084, including Appendices A and B; dated June 29, 2000; Boeing Alert Service Bulletin 757-21A0085, including Appendices A and B; dated June 29, 2000; or Boeing Alert Service Bulletin 767-21A0158; including Appendices A and B; dated June 29, 2000. 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.

(e) This amendment becomes effective on February 2, 2001.

FOR FURTHER INFORMATION CONTACT: James Cashdollar, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2785; fax (425) 227-1181.

Issued in Renton, Washington, on December 20, 2000.

John J. Hickey, Manager, Transport Airplane Directorate, Aircraft Certification Service.