AD 73-07-01

73-07-01 GENERAL DYNAMICS: Amdt. 39-1608. Applies to Model 340, 440 and C- 131E and all such model airplanes converted to turbopropeller power in accordance with STC SA1096WE and SA4-1100 known as Model 640 and Model 580, respectively, certificated in all categories.

Compliance as indicated required on all airplanes with 30,000 hours or more total time in service unless already accomplished.

To detect cracks in the wing front spar lower caps, accomplish the following:

(1) As soon as practicable, but not to exceed 10 hours' time in service following the effective date of this AD, if the airplane is to be flown, visually inspect, on a daily basis, from the exterior of the wing, both left and right wing front spar lower caps in areas adjacent to each side of main landing gear drag strut attachment fittings for cracks until inspection in (2) below is accomplished.

(2) Within the next 100 hours' time in service after the effective date of this A.D., unless already accomplished within the last 500 hours' time in service, and thereafter at intervals not to exceed 600 hours' time in service from the last inspection, accomplish the following:

(a) Gain access to the wing interior in the area described in (1) above by removal of lower wing skin access cover.

(b) Perform inspection described in (1) above from the interior of the wing.

(3) If cracks are found as the result of the inspections described in (1) or (2) above, repair before further flight in a manner approved by the Chief, Aircraft Engineering Division FAA Western Region.

This amendment becomes effective March 26, 1973.