57-13-01 COLONIAL: Applies to All Model C-1 Aircraft.
Compliance required within next 10 hours of operation or July 15, 1957, whichever occurs first unless already accomplished, and every 100 hours' operation thereafter.
Inspect with 10-power glass the engine pylon side strut attaching fittings (P/N 3208-10) for cracks in the weld areas. (Inspection may be readily accomplished after removal of the fairing cuff, P/N 5400-33.) Fittings with cracks originating across the edge may be salvaged for use if the crack can be removed by grinding to a maximum depth of 1/16 inch measured in from the edge. Fittings with cracks located in areas other than the edge or in excess of the salvage limits must be replaced.
(Colonial Service Bulletin No. 4 revision 1 dated May 22, 1957, covers this same subject.)