AD 89-20-04

89-20-04 BOEING: Amendment 39-6326. (Docket No. 89-NM-152-AD) Applicability: Model 727 series airplanes, line numbers 001 through 047, certificated in any category.

Compliance: Required as indicated, unless previously accomplished.

To prevent rapid decompression of the airplane, accomplish the following:

A. Within the next 15 days after receipt of AD T89-14-51, dated June 30, 1989, conduct an internal detailed visual inspection for cracks of the fuselage skin at lap joints located at stringer (S) 14L from body station (BS) 440 to BS 720, and at S-14R from BS 440 to BS 540, in accordance with the following instructions:

1. Remove seats, sidewall lining, and insulation as required to gain access to the internal portion of the fuselage skin at lap joints S-14L from BS 440 to BS 720, and at S-14R from BS 440 to BS 540.

2. Accomplish a detailed visual inspection of the fuselage skin along the bottom fastener row of the lap joint.

NOTE: The fastenerrow is immediately below the stringer.

3. Confirm all cracks with dye penetrant inspection or high frequency eddy current inspection.

4. If any cracks are detected, repair prior to further flight, in accordance with Boeing Drawing Number 65C35368 or 65C35369.

B. Within the next 500 landings after conducting the inspection required by paragraph A., above, or ten days after the effective date of this AD, whichever occurs later, accomplish the inspection specified in either paragraph B.1. or B.2., below:

1. Conduct a high frequency eddy current (HFEC) inspection as follows:

a. Remove seats, sidewall lining, and insulation as required to gain access to the internal portion of the fuselage skin at lap joints S-14L from BS 440 to BS 720, and at S-14R from BS 440 to BS 540.

b. Conduct an HFEC inspection of the lap joints, in accordance with the Accomplishment Instructions in Boeing Alert Service Bulletin 727-53A0200, Revision 1, dated July 20, 1989.2. Conduct a low frequency eddy current (LFEC) inspection of the lap joints, in accordance with the Accomplishment Instructions in Boeing Alert Service Bulletin 727-53A0200, Revision 1, dated July 20, 1989.

C. Repeat the inspections required by paragraph B., above, at the following intervals:

1. If the immediately preceding inspection was conducted using HFEC techniques, conduct the next inspection within 2,000 landings.

2. If the immediately preceding inspection was conducted using LFEC techniques, conduct the next inspection within 1,000 landings.

D. If any cracks are detected, repair prior to further flight, in accordance with Boeing Drawing 65C35368 or 65C35369. This repair constitutes terminating action for the inspections required by paragraph B.2. or C., above, in the areas repaired.

E. Modification of the lap joints at S-14L from BS 440 to BS 720, and at S-14R from BS 440 to BS 540, in accordance with Boeing Drawing 65C35402 constitutes terminating action for the repetitive inspections required by paragraphs C.1. and C.2., above.

F. An alternate means 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.

NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector (PMI), who will either concur or comment and then send it to the Manager, Seattle Aircraft Certification Office.

G. 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.

All persons affected by this directive who have not already received the appropriate service information from the manufacturer may obtain copies upon request to Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124. This information may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 17900 Pacific Highway South, Seattle, Washington, or Seattle Aircraft Certification Office 9010 East Marginal Way South, Seattle, Washington.

This AD supersedes Telegraphic Airworthiness Directive T89-14-51, issued on June 30, 1989. This amendment (39-6326, AD 89-20-04) becomes effective on October 6, 1989.