AD 92-02-13

92-02-13 BOEING: Amendment 39-8149. Docket No. 91-NM-168-AD.

Applicability: Model 747 series airplanes; as listed in Boeing Alert Service Bulletin 747- 21A2312, and in Boeing Service Bulletin 747-21-2317, both dated May 30, 1991, certificated in any category.

Compliance: Required within the next 60 days after the effective date of this AD, unless previously accomplished.

To reduce the potential for an uncontrollable fire in the aft lower lobe compartment, accomplish the following:

(a) Install a decompression panel and flapper valve in accordance with Boeing Alert Service Bulletin 747-21A2312 or Boeing Service Bulletin 747-21-2317, both dated May 30, 1991, as applicable.

(b) An alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate.

NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Seattle ACO.

(c) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.

(d) The installation required by this AD shall be done in accordance with Boeing Alert Service Bulletin 747-21A2312, dated May 30, 1991; or Boeing Service Bulletin 747-21- 2317, dated May 30, 1991. 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. Copies may be inspected at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington, or at the Office of the Federal Register, 1100 L Street N.W., Room 8401, Washington, D.C.

(e) This amendment (39-8149, AD 92-02-13) becomes effective on March 25, 1992.