AD 81-11-06 R1

81-11-06 R1 BOEING: Amendment 39-4121 as amended by Amendment 39-4178. Applies to all 707/720 series airplanes, certificated in all categories.

A. Inspect stringers 5 and 7 and the adjacent lower wing skin from WS 265 through 470 for cracks using the specified methods at the times indicated. Skins/stringers found cracked must be repaired prior to further flight in a manner approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region.

1. For 720/720B series airplanes:

Within 500 landings after the effective date of this Amendment and thereafter at intervals not to exceed 2,860 landings, conduct a low frequency eddy current inspection of the wing lower surface for cracks in the stringer/skin between wing stations 265 and 470 and stringers 5 and 7 in accordance with Boeing Service Bulletin A3395, Revision 2, dated October 10, 1980, or later FAA approved revisions, or in a manner approved by the Chief, Seattle Area Aircraft CertificationOffice.

2. For 707 series airplanes:

Inspect the wing lower surface for stringer/skin cracks between wing stations 265 and 470 and stringers 5 and 7. For the 707-300C airplanes, if ever used as a cargo airplane, inspect between wing Buttock Line 59.24 and wing station 470 and stringers 5 and 7. Inspect internally using high frequency eddy current or inspect externally using low frequency eddy current procedures as described in Boeing Service Bulletin A3395, Revision 3, dated July 17, 1981, or later FAA approved revisions or in a manner approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region. Inspect in accordance with the table noted below.

AIRPLANE THRESHOLD (Landings) WITHIN (Landings) UNLESS ACCOMPLISHED Within the last Landings) External/Internal Low Freq/High Freq REPEAT INTERVAL (Landings) External/Internal Low Freq/High Freq 707-100/200 26,000 500 2,000/5,500 2,500/6,000 707-300/400 20,000 500 1,450/4,500 1,950/5,000 707-300B 17,000 500 1,150/3,700 1,150/3,700 707-300C (PAX) 17,000 500 1,200/3,700 1,700/4,200 707-300C (CGO) 17,000 500 400/1,600 900/2,100

B. Airplanes may be flown to a maintenance base for repairs or replacement in accordance with FAR 21.197 and FAR 21.199.

Alternate methods of compliance may be used when approved by the Chief, Seattle Area Aircraft Certification Office, Northwest Region.

The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1).

All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to The Boeing Company, P.O. Box 3707, Seattle, Washington 98124. These documents also may be examined at FAA Northwest Region, 9010 East Marginal Way South, Seattle, Washington 98108.

NOTE: This supersedes AD 80-15-10 (Amdt. 39-3852; 45 FR 49910, July 28, 1980).

Amendment 39-4121 became effective June 29, 1981.

This Amendment 39-4178 becomes effective August 10, 1981.