47-21-23 REPUBLIC: (Was Service Note 3 of AD-769-2.) Applies to Model RC-3 Aircraft with Engine Serial Numbers 23001 to 24083, Inclusive.
Compliance required before the next flight and after 5 hours of operation following each installation of fan.
Inspect the engine cooling fan capscrews for tightness. If tab locks are installed ascertain whether the locks are still in place. If the capscrews or the locks have loosened remove the capscrews, fan and pulley sheave. Clean and inspect parts for wear. Reassemble carefully using P/N 17778 drilled head capscrews with plain washers. Torque to 20 foot-pounds, operate engine up to 1,500 r.p.m. for 5 minutes, retorque and safety with 0.041-inch stainless steel wire. Visually inspect locking wire and capscrews after 5 hours of operation. Reassemble in this manner every time the fan is removed.
Obtain the new capscrews, washers, and wire from your Seabee distributor or the engine manufacturer.
(Franklin Service Bulletin No. 57 dated June 9, 1947, which supersedes Bulletin No. 50 covers this same subject.)