47-40-02 CONTINENTAL: (Was Mandatory Note of Airworthiness Directive Supplement Dated October 3, 1947.) Applies Only to the Following Models: Cessna 120 and 140, Commonwealth (Rearwin) 185, Superior (Culver) V and V2, Air Products (Erco) 415C, McClish (Funk) B85C, Universal (Globe) GC-1A, GC-1B, Silvaire (Luscombe) 8E, and Piper J3C-65, J4E, J5A Having Continental C75-12 or -12F Engines With Serial Numbers Below 1794-6-12 Except 1788-6-12: Airplanes Having Continental C85-12, -12F or -12FHJ Engines With Serial Numbers Below 20668-6-12 Except: 20656-6-12, 20658-6-12, 20659-6-12, 20661-6-12, and 20666- 6-12; Airplanes Having Continental C125-1 or -2 Engines With Serial Numbers Below 1046-6-12 Except: 1034- 6-12, 1037-6-12 Through 1042-6-12, and 1044-6-12.
Compliance required immediately if engine has attained or passed 600-hour major overhaul period, but in any event not later than December 31, 1947, or 600 hours of operation, whichever occurs first.
A certain percentage of piston pins installed in engines of the above numbers and distributed as replacement parts are subject to failure without warning. The weakness of these pins cannot be detected by normal inspection methods. Piston pin breakage can result in complete engine failure. It is the owner's responsibility to avoid this risk by making the following change at the earliest possible time.
Replace piston pin assembly No. 22248-A1 (0.6875-inch inside diameter) with thick wall piston pin assembly No. 25121-A1 or 25262-A1 (0.5945-inch inside diameter). Supplies of the heavy wall pins are adequate so that immediate replacement can be effected.
(Continental Service Bulletin No. M47-9 covers this same subject.)