Fuselage Lap Joints

Category - Airframe
Effective Date - 12/14/1998
 Recurring - No
Supersedes - N/A
 Superseded by - N/A
Amendment 39-10932.
Docket 98-NM-319-AD

Applicability: Model 727 series airplanes, line positions 1 through 849 inclusive; that have been converted from a passenger-carrying to a cargo-carrying ("freighter") configuration, or to a passenger- and cargo-carrying ("combi") configuration; certificated in any category.

Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise 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 (g) 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.

To prevent corrosion and subsequent fatigue cracking of the fuselage skin lap joints, which could result in rapid decompression of the airplane, accomplish the following:

(a) Within 60 landings after the effective date of this AD, perform a detailed internal visual inspection to detect cracking, corrosion, or delamination of the fuselage skin lap joints where those lap joints are covered by external doublers at stringers S-4L, S-10L, S-19L, and S-26L from body station 360 to 740; in accordance with task numbers C53-224-01 and C53-111-01 of Boeing Document D6-54929, "Aging Airplane Corrosion Prevention and Control Program, Model 727," Revision A, dated July 28, 1989. The lap joints must be completely exposed to perform the inspection.

(1) If no cracking, corrosion, or delamination is found, repeat the inspection required by paragraph (a) of this AD thereafter at intervals not to exceed 60 landings until the modification required by paragraph (b) of this AD is accomplished.

(2) If any crack, corrosion, or delamination is found, prior to further flight, repair damaged structure in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Thereafter, repeat the inspection required by paragraph (a) of this AD at intervals not to exceed 60 landings until the modification required by paragraph (b) of this AD is accomplished.

(b) Modify the fuselage skin lap joints where those lap joints are covered by external doublers at stringers S-4L, S-10L, S-19L, and S-26L from body station 360 to 740 by removing the external doublers; and by separating and reworking the joint in accordance with Part IV, Figure 4, of the Accomplishment Instructions of Boeing Service Bulletin 727-53-0072, Revision 5, dated June 1, 1989, except that blind fasteners shall not be installed. Before oversizing the fastener holes as part of the modification, perform a high frequency eddy current inspection of the holes to detect cracking, in accordance with the service bulletin; and, prior to further flight, repair any cracking in accordance with a method approved by the Manager, Seattle ACO. When reassembling the lap joint, all three rows of fasteners must penetrate all layers of the lap joint, including the upper skin, lower skin, and the doublers; and the stringers and tripler, as applicable. Accomplish the modification at the latest of the times specified in paragraphs (b)(1), (b)(2), and (b)(3) of this AD.

(1) Prior to the accumulation of 28,000 total landings.

(2) Within 250 landings after the effective date of this AD.

(3) Within 120 days after the effective date of this AD.

Note 2: Installation of protruding head fasteners in the upper row of fasteners of the lap joint in itself does not constitute accomplishment of the modification.

(c) For airplanes on which the cargo door itself was manufactured using the original fuselage skin, paragraphs (a) and (b) of this AD also apply to the lap joint(s) in the door structure.

(d) Accomplishment of the modification required by paragraph (b) of this AD constitutes terminating action for the inspections required by paragraph (a) of this AD, and constitutes an acceptable alternative method of compliance with paragraph F. of AD 91-06-06 for the affected area.

(e) Contrary provisions of AD 91-06-06 notwithstanding, this AD allows continued operation of the subject airplanes following the effective date of this AD in accordance with the terms of this AD, provided that the modification required by AD 91-06-06 has been accomplished on all lap joints other than those in the area of the main deck cargo door.

(f) For any airplane that, as of the effective date of this AD, is being, or will be converted from a passenger-carrying to a cargo-carrying ("freighter") configuration, or to a passenger-and cargo-carrying ("combi") configuration: After the effective date of this AD, no such airplane shall be returned to service following such conversion unless the modification required by paragraph (b) of this AD has been accomplished on that airplane.

(g) 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 ACO. 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 3: Alternative methods of compliance, approved previously in accordance with AD 91-06-06, amendment 39-6921, are not considered to be approved as alternative methods of compliance with this AD.

Note 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

(h) 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.

(i) The actions shall be done in accordance with Boeing Service Bulletin 727-53-0072, Revision 5, dated June 1, 1989; and Boeing Document D6-54929, "Aging Airplane Corrosion Prevention and Control Program, Model 727," Revision A, dated July 28, 1989.

(1) The incorporation by reference of Boeing Service Bulletin 727-53-0072, Revision 5, dated June 1, 1989, is approved by the Director of the Federal Register, in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.

(2) The incorporation by reference of Boeing Document D6-54929, "Aging Airplane Corrosion Prevention and Control Program, Model 727," Revision A, dated July 28, 1989, was approved previously by the Director of the Federal Register as of December 31, 1990 (55 FR 49258, November 27, 1990).

(3) 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.

(j) This amendment becomes effective on December 14, 1998, to all persons except those persons to whom it was made immediately effective by telegraphic AD T98-23-51, issued on November 27, 1998, which contained the requirements of this amendment.

Issued in Renton, Washington, on December 1, 1998. John J. Hickey, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.