49-40-02 PRATT & WHITNEY: Applies to Double Wasp CA Series (-3, -5, -15, -18) and Military R-2800-C Series (-22, -22W, -34, -34W, -57, -73, -77, -81, -83, -85) Engines.
To be accomplished at next overhaul but in no case later than March 1, 1950.
To preclude the possibility of complete loss of power as a result of failure of the supercharger impeller thrust bearing, the engine must be modified to incorporate a new thrust plate P/N 127770 with larger (No. 51) oil feed holes. Also P/N 84012 thrust spacer must be reworked to incorporate circumferential oil skates. Details off this modification and rework are given in Pratt & Whitney Service Bulletin No. 892, Revision B.
As a precautionary measure, it is recommended that the engine be operated with minimum use of high ratio supercharger and that particular attention be directed toward keeping oil sludge to a minimum until the above modification has been accomplished.