AD 92-13-08

92-13-08 BOEING: Amendment 39-8278. Docket No. 92-NM-13-AD.

Applicability: Model 747-400 series airplanes; as listed in Boeing Alert Service Bulletin 747-38A2090, dated November 21, 1991; certificated in any category.

Compliance: Required within 12 months after the effective date of this AD, unless accomplished previously.

To prevent fires in the drain mast internal space, accomplish the following:

(a) Install shields with sealant over the mid and aft drain masts in accordance with Boeing Alert Service Bulletin 747-38A2090, dated November 21, 1991.

(b) Install moisture resistant and thermal insulation tape around the forward drain tube and heater elements on the mid and aft drain masts in accordance with Boeing Alert Service Bulletin 747-38A2090, dated November 21, 1991.

(c) 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. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Seattle ACO.

NOTE: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Manager, Seattle ACO.

(d) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.

(e) The installations shall be done in accordance with Boeing Alert Service Bulletin 747-38A2090, dated November 21, 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, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington; or at the Office of the Federal Register, 1100 L Street NW., Room 8401, Washington, DC.

(f) This amendment becomes effective on August 5, 1992.