54-01-02: Stop Levers

54-01-02 HAMILTON STANDARD: Applies to Hamilton Standard Reversing Propellers Models 43D, 43E, 34D, 34E, 232 and 242 Incorporating Low Pitch Stop Assemblies With Wedge Return Springs; and Models 43E, 34D, 232 and 242 Incorporating Low Pitch Stop Assemblies With Wedge Inserts, on Boeing 377, Convair 240 and 340 Series, Douglas DC-6 Series, Lockheed 49 Series, Martin 202 and 404 Series Aircraft. Compliance required as indicated. Investigations of three recent incidents in commercial service in which the propeller inadvertently reversed during approach, have indicated the possibility that the low pitch stop wedge, under vibratory conditions, can move forward from its position under the stop levers, allowing the propeller to travel into the reverse range upon governor demand for lower pitch. Therefore, to minimize the forward forces applied against the stop wedge by piston-to-stop-lever contact at the low pitch position, it is necessary to remove the 2 degree pitch angle fromthe stop lever and wedge contact surfaces. Prior to June 1, 1954, rework all low pitch stop levers and wedges as specified in Hamilton Standard Service Bulletin No. 273 and its Supplement No. 273A. This supersedes AD 53-15-01.