AD 46-13-04

46-13-04 DOUGLAS: (Was Service Note 10 of AD-618-3 and Service Note 11 of AD-669-3.) Applies to All DC3 Models Except Conversions From the C-47 Series.

1. Inspect visually for cracks all landing gear rear brace strut fittings, P/N 230659, that have not been removed and magnetically inspected at last airplane overhaul. This inspection should be accomplished prior to next flight.

2. If crack is less than 1/8-inch long it may be ground or filed out, being careful to remove all marks and scratches, without removing the fitting, until the next overhaul. If cracks are found to be longer than 1/8 inch, the fitting must be removed and repaired in accordance with paragraph 3 below.

3. Cracks in weld area can be repaired by grinding away all existing weld and rewelding. If cracks extend through spacer plate, the spacer plate may be cut back beyond the end of crack, all old weld removed, and a new section of spacer plate lap welded to the remaining portion of the spacer plate and then seam welded to the side plates. Cracks extending through the side plates for a maximum of 1/4 inch may be repaired by grinding a "V" on the outside surface of the plate to a minimum of 1/16 inch beyond the end of the cracks and welding. The weld must be ground smooth.

4. If fitting is removed, rivets may be replaced with spacers and 3/16-inch AN bolts having a ream fit through the bulkhead and fitting in order to facilitate installation.

5. In order to insure that parts in the airplane continue to remain satisfactory for service, the following inspection procedure should be followed:

(a) Visually inspect landing gear rear brace strut fitting at periods not to exceed 1,000 hours.

(b) Remove and magnetically inspect rear brace strut fitting at each major overhaul.

(The inspection and repair outlined above are covered by Douglas Service Bulletin No. 233, Section IV.).

The inspections outlined above will not be necessary when the landing gear rear brace strut fitting, P/N 230659, is replaced by the new fitting, P/N 4341810.

(Supplement to Douglas Service Bulletin No. 233, as revised October 24, 1946, covers this same subject.)