AD 68-10-04 ACTIVE

68-10-04 GENERAL DYNAMICS: Amendment 39-597 as amended by Amendment 39- 1305 is further amended by Amendment 39-2247. Applies to Models 340, 440, and C-131E airplanes including those using turbo propeller power.

Compliance required as indicated.

Due to several reports of cracks in the front spar lower rail which can result in failure of the outboard wing, accomplish the following:

(a) For airplanes with 23,500 or more hours time in service on the effective date of this AD, inspect each front spar lower rail per (c) within the next 300 hours time in service, unless already accomplished within the last 700 hours time in service, and thereafter at intervals not to exceed 1000 hours time in service from the last inspection, and, if cracks are found, repair per (d) before further flight (except that the airplane may be flown in accordance with FAR 21.197 to a base where the repair can be accomplished).

(b) For airplanes with less than 23,500 hours time in service on the effective date of this AD, inspect each front spar lower rail per (c) before the accumulation of 23,800 hours time in service, and thereafter at intervals not to exceed 1000 hours time in service from the last inspection, and, if cracks are found, repair per (d) before further flight (except that the airplane may be flown in accordance with FAR 21.197 to a base where the repair can be accomplished).

(c) Remove the wig leading edge and visually inspect the wing front spar lower rail between wing stations 240 and 490 for cracks.

NOTE: During the inspection required by (c), pay particular attention to the areas immediately adjacent to the leading edge joints at wing stations 248, 264, 363 and 484. All reported cracks have originated in the rail forward flange at or near the leading edge attach screw holes.

(d) If a crack is confined to the wing front spar lower rail, repair in accordance with General Dynamics/Convair Service Engineering Report No. 057-0/67-340-64/440-64/640-35, (Revision 1 or later FAA approved Revision) or a method approved by the Chief, Aircraft Engineering Division, Federal Aviation Administration, Western Region. If a crack extends beyond the spar rail into adjacent components, repair in accordance with a method approved by the Chief, Aircraft Engineering Division, FAA Western Region.

(e) The repetitive inspections required in (a) and (b) may be discontinued when all cracks, if any, have been repaired per (d) and, unless already accomplished per (d), a reinforcing strap has been installed per details (a) and (b), Figure 1, of General Dynamics/ Convair Service Engineering Report No. 057-0/67-340-64/440-64/640-35 or a rework approved by the Chief, Aircraft Engineering Division, FAA Western Region has been accomplished.

(f) Upon request of the operator, an FAA Air Carrier Maintenance Inspector, subject to prior approval of the Regional Director, 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 that operator.

Amendment 39-597 became effective on May 14, 1968.

Amendment 39-1305 became effective October 8, 1971.

This amendment 39-2247 becomes effective July 30, 1975.