AD 61-06-03

61-06-03 DOUGLAS: Amdt. 264 Part 507 Federal Register March 11, 1961. Applies to All DC-7 and DC-7B Aircraft, Fuselage Numbers 1 to 720 Inclusive, Having in Excess of 8,000 Hours' Time in Service.

Compliance required as indicated.

There have been thirteen (13) reported cases of upper front spar cap cracking on DC-7 Series aircraft. Cracking usually occurs in spar cap tangs in the area of the Station 60 attachments and progresses chordwise. In addition, service experience has shown that the temporary repair of the above difficulty per Douglas Rework Drawing 5611387 does not have the service life originally anticipated. As a result of this service experience, the upper and lower, front and center spar caps in the area of wing Station 60, with special attention to the spar cap tangs between wing Stations 55 and 65, must be visually or radiographically inspected for cracks as follows:

(a) The upper and lower, front and center spar caps must be inspected within the next 450 hours' time in service unless already accomplished. Aircraft inspected prior to issuance of this AD must also comply with the repetitive inspections, rework and/or repairs specified in (b), (c), (d), and (e).

(b) The upper front and center spar caps must be reinspected at intervals not to exceed 1,600 hours' time in service.

(c) The lower front and center spar caps must be reinspected at intervals not to exceed 3,250 hours' time in service.

(d) If cracks are found, FAA approved permanent rework or temporary repair of the spar cap is required prior to further flight except ferry flight in accordance with provisions of CAR 1.76. Temporary repairs may be made per Douglas Rework Drawing 5611387, or FAA approved equivalent, providing crack limitations as established on this drawing have not been exceeded. Douglas DC-7 Service Bulletin No. 167 revised June 3, 1960, contains an FAA approved permanent rework consisting of Kit X plus the appropriate kits from the following list as indicated on Page 4 of the service bulletin: A, B, C, D, E, S, U, H, J, K, L.

(e) Aircraft incorporating a temporary repair must be reinspected at intervals not to exceed 750 hours' time in service pending the accomplishment of an FAA approved permanent rework. Permanent rework must be accomplished within 4,200 hours' time in service after incorporating the temporary repair.

(f) The special inspections specified in this AD are no longer required after an FAA approved permanent rework is accomplished.

(Douglas DC-7 Service Bulletin No. 167 revised June 3, 1960, covers this subject.)

This directive effective April 11, 1961.

Revised May 6, 1961.