# AD 68-17-08: Lower Wing Skin - Type: Airworthiness directive - Status: Current - Products: Boeing 707-100 Long Body, 707-100B Long Body, 707-100B Short Body, 707-200, 707-300 Series, 707-300B Series, 707-300C Series, 707-400 Series, 720 Series and 720B Series - Effective: April 1, 1972 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Large airplane - Amendment: 39-1420 - Registered aircraft: 6 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/0858ADA8EFDA3A5786256E0100546CFA.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/68-17-08 ## The airworthiness directive 68-17-08 BOEING: Amendment 39-640 as amended by Amendments 39-670, 39-852, 39- 891, and 39-923 is further amended by Amendment 39-1420. Applies to all Boeing 707/720 series aircraft listed in Boeing Service Bulletin 1995 (Revision 5) dated September 28, 1967 or later FAA approved revision. Compliance required as indicated. To detect cracking and prevent failure of the lower wing skin at front spar station 392, accomplish the following: (a) Inspect the lower wing skin of aircraft which have not been repaired by installation of the small repair doubler (identified on Page 25, Boeing Service Bulletin 1995, Revision 5), for cracks emanating from the two outboard fasteners of the splice plate tab as noted in Figure 1 of Boeing Service Bulletin 1995, (Revision 5 or later FAA approved revisions) by the use of either a dye penetrant or an eddy current inspection technique, or an equivalent inspection method approved by the Chief, Aircraft Engineering Division, FAA Western Region, atthe times specified in (h), (i), (j) or (k) as appropriate and, if cracks are found, repair prior to further flight per (f) or (g). (b) Inspect the lower wing skin of aircraft which have been repaired by installation of the small repair doubler in accordance with Boeing Service Bulletin 1995, within 1600 hours (for 720 Series) or 2000 hours (for 707 Series) after installation or within the next 400 hours (for 720 Series) or 600 hours (for 707 Series) time in service after the effective date of this AD, unless inspected within the previous 1200 (for 720 Series) or 1400 (for 707 Series) hours time in service and at intervals thereafter not to exceed 1600 (for 720 Series) or 2000 (for 707 Series) hours time in service, per (e). (c) Inspect the lower wing skin for cracks emanating from the attachments of the front spar support fitting as noted in Figure 1 of Boeing Service Bulletin 1995 (Revision 7) dated 20 August 1969 or later FAA-approved revisions, at the times specified in (h),(i), (j), or (k) as appropriate, and, if cracks are found, repair prior to further flights per (g). The initial inspection must be accomplished either by means of a dye penetrant technique or in accordance with the eddy current inspection technique described by S.B. 1995 (Revision 7) or later FAA-approved revisions, or an equivalent inspection approved by the Chief, Aircraft Engineering Division, FAA Western Region. The eddy current inspection technique described by S.B. 1995 (Revision 7) or later FAA-approved revision, or an equivalent FAA-approved inspection technique, must be used for all inspections thereafter. (d) On those aircraft which have not had the drag fitting trimmed and the fairing attach angle modified in accordance with Boeing Service Bulletin 1995 (Revision 7) or later FAA- approved revisions, within the next 400 hours (for 720 Series) or 600 hours (for 707 Series) time in service after the effective date of this AD and thereafter at intervals not to exceed 800 hours (for 720 Series) or 1,200 hours (for 707 Series) time in service, inspect for cracks in the lower wing skin, emanating from the forward fastener for the drag fitting and from the fasteners for the fairing attach angle as noted in Figure 1 of Boeing Service Bulletin 1995 (Revision 7) or later FAA-approved revisions, at the threshold times as specified in (h), (i), (j), or (k) as appropriate. The initial inspection must be accomplished either by means of a dye penetrant technique or by use of eddy current inspection techniques described in S.B. 1995 (Revision 7), or later FAA- approved revisions, or an equivalent inspection approved by the Chief, Aircraft Engineering Division, FAA Western Region. The eddy current inspection technique described by S.B. 1995 (Revision 7) or later FAA-approved revision, must be used for all inspections thereafter. If cracks are found around the fairing attach angle or emanating aft from the drag fitting fastener, rework the drag fitting, double, andskin prior to further flight in accordance with (g). If cracks are found emanating forward from the drag fitting fastener, rework the drag fittings, doubler and skin, prior to further flight in accordance with Boeing Service Bulletin 1995 (Revision 7) or later FAA-approved revision, or in accordance with an equivalent rework or modification approved by the Chief, Aircraft Engineering Division, FAA Western Region. (e) Inspect the lower wing skin covered by the small repair doubler for cracks by use of the x-ray inspection techniques noted in Boeing Service Bulletin 1995 (Revision 5 or later FAA- approved revisions) or an equivalent inspection technique approved by the Chief, Aircraft Engineering Division, FAA Western Region. Repeat inspections at intervals not to exceed 1600 hours (for 720 Series) or 2000 hours (for 707 Series) time in service. If crack growth is found, repair prior to further flight in accordance with (g). (f) If the cracks fall within the crack length limitsoutlined in the paragraph titled "Installation of the small repair doubler," (Part II, Boeing Service Bulletin 1995, Revision 5 or later FAA-approved revisions) repair in accordance with that section of the bulletin or later FAA- approved revisions. Within 1600 hours (for 720 Series) or 2000 hours (for 707 Series) after installation of the doubler, inspect in accordance with (e). (g) Upon completion of any of the following modifications, the inspections required by this AD may be discontinued: (1) Installation of 65-56257-1-2 or 65-57788-1-2 doublers as appropriate, per Boeing Service Bulletin 1995 (Revision 5 or later FAA-approved revisions). (2) Boeing Service Bulletin 2484. (3) Boeing Service Bulletin 2487. (4) Installation of the 720 Wing Structural Improvement Program (Per Boeing Document 65-12700) accomplish at Boeing's Wichita facility. (5) An equivalent installation approved by the Chief, Aircraft Engineering Division, Western Region, FAA. (h) For those airplanes listed in Boeing Service Bulletin 1995 (Revision 5 or later FAA- approved revisions) Part I, and having less than 6000 (for 720 Series) or less than 10,000 (for 707 Series) hours time in service on the effective date of this AD, prior to the accumulation of 6800 (for 720 Series) or 11,200 (for 707 Series) hours time in service, respectively, and thereafter not to exceed 800 (for 720 Series) or 1200 (for 707 Series) hours time in service from the last inspection. (i) For aircraft listed in Boeing Service Bulletin 1995 (Revision 5 or later FAA- approved revisions) Part I, and having 6000 or more (in the case of 720 Series aircraft) or 10,000 or more (in the case of 707 Series aircraft) hours time in service on the effective date of this AD, within the next 400 (for 720 Series) or 600 (for 707 Series) hours time in service, unless accomplished within the last 400 (for 720 Series) or 600 (for 707 Series) hours time in service, and at intervals thereafter not to exceed 800 (for 720 Series) or 1200 (for 707 Series) hours time in service. (j) For aircraft listed in Boeing Service Bulletin 1995 (Revision 5 or later FAA- approved revisions) Part II, and having less than 10,000 (in the case of 720 Series) or less than 15,000 (in the case of 707 Series) hours time in service on the effective date of this AD, prior to the accumulation of 10,800 or 16,200 hours time in service, respectively, and thereafter at intervals not to exceed 800 (for 720 Series) or 1200 (for 707 Series) hours time in service from the last inspection. (k) For aircraft listed in Boeing Service Bulletin 1995 (Revision 5 or later FAA- approved revisions) Part II, and having 10,000 or more (in the case of the 720 Series) or 15,000 or more (in the case of the 707 Series) hours time in service on the effective date of this AD, within the next 400 (for 720 Series) or 600 (for 707 Series) hours time in service unless accomplished within the last 400 (for 720 Series) or 600 (for 707 Series) hours time in service, and at intervals thereafter not to exceed 800 (for 720 Series) or 1200 (for 707 Series) hours time in service. (l) Airplanes having cracks which require rework under this AD may be flown in accordance with FAR 21.197 with the concurrence of Chief, Aircraft Engineering Division, FAA Western Region, to a base where the rework can be accomplished. (m) Upon request of an operator, an FAA maintenance inspector, subject to prior approval of the Chief, Aircraft Engineering Division, FAA Western Region, may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period of the operator if the request contains substantiating data to justify the increase for such operator. Amendment 39-640 became effective September 23, 1968. Amendment 39-670 became effective October 18, 1968. Amendment 39-852 became effective November 1, 1969. Amendment 39-891 became effective December 16, 1969. Amendment 39-923became effective January 17, 1970. This Amendment 39-1420 becomes effective April 1, 1972. ## Affected data sheets (3) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS 4A21](https://openairdocs.org/tcds/4A21): The Boeing Company; names 4 of 4 models: 707-100B Short Body, 707-200, 707-100 Long Body, 707-100B Long Body - [TCDS 4A26](https://openairdocs.org/tcds/4A26): The Boeing Company; names 4 of 4 models: 707-300B Series, 707-400 Series, 707-300 Series, 707-300C Series - [TCDS 4A28](https://openairdocs.org/tcds/4A28): The Boeing Company; names 2 of 2 models: 720B Series, 720 Series ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 6 (6 by airframe model, 0 by engine model) - Makers: Boeing 6 Models with the most aircraft: - [Boeing 707-338C](https://openairdocs.org/model/boeing-707-338c): 2 aircraft (airframe model) - [Boeing 707-368C](https://openairdocs.org/model/boeing-707-368c): 1 aircraft (airframe model) - [Boeing 707-321B](https://openairdocs.org/model/boeing-707-321b): 1 aircraft (airframe model) - [Boeing 707-323B](https://openairdocs.org/model/boeing-707-323b): 1 aircraft (airframe model) - [Boeing 707-351B](https://openairdocs.org/model/boeing-707-351b): 1 aircraft (airframe model) All 5 models: https://openairdocs.org/ad/68-17-08/models.md Every aircraft: https://openairdocs.org/ad/68-17-08/aircraft.md Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.