AD 74-03-04

74-03-04 GENERAL DYNAMICS: Amdt. 39-1781. Applies to Model 240 series and T- 29B airplanes including those modified for Turbo-propeller power per STC SA1054WE certificated in all categories.

Compliance required as indicated.

To detect cracks in the Pilot and Copilot direct vision window frame castings, P/N's 240- 3110314-6 and -7 (hereinafter referred to as the casting) which could result in failure in flight and consequent rapid decompression, accomplish the following:

(a) Inspect each casting with 4500 or more hours' time in service on the effective date of this AD for cracks in accordance with (c), below, within the next 250 hours' time in service after the effective date of this AD unless already accomplished within the last 750 hours' time in service, and thereafter at intervals not to exceed 1000 hours' time in service from the last inspection.

(b) Inspect each casting with less than 4500 hours' time in service on the effective date of this AD for cracks inaccordance with (c), below, prior to the accumulation of 4750 hours' time in service and thereafter at intervals not to exceed 1000 hours' time in service from the last inspection.

(c) Inspect the castings in accordance with Paragraph 2B of General Dynamics Service Bulletin 600 (240D), S.B. No. 53-2A, dated December 21, 1973, or later FAA-approved revisions, or by a method approved by the Chief, Aircraft Engineering Division, FAA Western Region.

(d) If a crack is found, comply with (1) or (2), below, as appropriate:

(1) If the crack completely severs the frame at any point, replace the casting with a new part, P/N 240-3110314-6 or -7, prior to further flight, except that the airplane may be flown with a zero differential cabin pressure in accordance with FAR 21.197 to a base where the replacement can be accomplished.

(2) If the crack does not completely sever the frame at any point, replace the casting with a new part, P/N 240-3110314-6 or -7, within 250 hours' time in service after crack discovery, except that, until such time as the casting is replaced, the following shall apply:

(i) The airplane must be operated at a zero differential cabin pressure.

(ii) Prior to take off after crack discovery, an operating limitation in the form of a placard must be installed in clear view of the pilot stating: "Operation Limitation. Pressurized Flight Prohibited."

(e) Operators who have not kept records of hours' time in service of individual castings shall substitute hours' time in service of the airplane in lieu thereof.

(f) Upon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Aircraft Engineering Division, FAA Western Region, may adjust the compliance times herein if the request contains substantiating data to justify the increase for that operator.

This amendment becomes effective on February 4, 1947.