AD 92-24-07

92-24-07 BOEING: Amendment 39-8412. Docket No. 92-NM-38-AD.

Applicability: Boeing Model 747-300, 747-400, and 747-100B series airplanes delivered with stretched upper decks, and Boeing Model 747 series airplanes modified to have stretched upper decks; as listed in Boeing Service Bulletin 747-53-2327, dated December 5, 1991; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent reduced controllability of the airplane as a result of failure of the upper floor beams and probable interference with the control cables, accomplish the following:

(a) Conduct a high frequency eddy current inspection of the Body Station (BS) 860 and BS 980 upper deck floor beams to detect cracks, in accordance with Boeing Service Bulletin 747-53-2327, dated December 5, 1991, at the applicable time specified in subparagraph (a)(1) or (a)(2) of this AD. If cracks are found as a result of this inspection, prior to further flight, repair in a manner approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate.

(1) For Boeing Model 747-300, -400, and -100B series airplanes delivered with stretched upper decks: Prior to the accumulation of 20,000 flight cycles, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later.

(2) For Boeing Model 747 series airplanes modified to have stretched upper decks: Prior to the accumulation of 20,000 flight cycles after incorporation of the stretched upper deck modification, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later.

(b) If no cracks are found as a result of the inspection required by paragraph (a) of this AD, reinforce the BS 860 and BS 980 upper deck floor beams in accordance with Boeing Service Bulletin 747-53-2327, dated December 5, 1991, at the applicable time specified in subparagraph (b)(1) or (b)(2) of this AD.

(1) For Boeing Model 747-300, -400, and -100B series airplanes delivered with stretched upper decks: Prior to the accumulation of 20,000 flight cycles, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later.

(2) For Boeing Model 747 series airplanes modified to have stretched upper decks: Prior to the accumulation of 20,000 flight cycles after incorporation of the stretched upper deck modification, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later.

(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, 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.

NOTE: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the 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 inspection and reinforcement shall be done in accordance with Boeing Service Bulletin 747-53-2327, dated December 5, 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 98124-2207. 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 December 15, 1992.