60-10-04 LOCKHEED: Amdt. 138 Part 507 Federal Register May 3, 1960. Applies to All Models 049, 149, 649, 749, 1049, and 1649 Series Aircraft.
Compliance required as indicated.
A crack was found in the segment ring of the fuselage aft pressure bulkhead. The crack, approximately 37 inches long, was in the top left section of the ring, extending from a point right of center. As a result of investigation of the failure, the following must be accomplished on all aircraft with more than 30,000 hours' time in service.
(a) Within the next 180 hours' time in service, unless already accomplished within the last 4,500 hours' time in service, and every 4,500 hours' time in service thereafter, inspect the entire peripheral ring of the aft pressure bulkhead at the bend radius adjacent to the skin using one of the following methods or equivalent:
(1) Radiographic inspection.
(2) Pressurize the cabin to a minimum of 2 p.s.i. Apply soap solution to the rear face of thering and examine for leakage. This will require removal of the sealing compound.
(b) If cracks are found, they must be repaired in accordance with FAA approved manufacturer's instructions. Pressurized flight is prohibited until cracks are repaired.
(c) When any part of the aft pressure bulkhead peripheral ring is replaced by a new part, inspection of the new part per (a) is not required until the new part has accumulated 30,000 hours' time in service.
(d) Upon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, 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.
(Lockheed Service Letter FS/240954 covers this subject.)
Revised July 11, 1961.
Revised March 9, 1962.