What was found
DURING NORMAL CRUISE FLT, PILOT NOTICED AN UNUSUAL VIBRATION COMING FROM THE RT ENGINE. SHUT DOWN ENGINE AS A PRECAUTION AND MADE A SINGLE ENGINE LANDING. MAINTENANCE REMOVED SPINNER FROM THE RT PROPELLER AND FOUND THAT THE REVERSE CONTACT SLEEVE HAD BACKED OUT APPROX. .2500 INCH. PROP CYLINDER WAS REMOVED AND REVERSE CONTACT SPRING WAS INSPECTED AND FOUND TO BE OK. CYLINDER WAS REINSTALLED AND AIRCRAFT WAS GROUND RUN TO OPS CHECK, FOUND ALL INDICATIONS AND OPERATIONS NORMAL. AIRCRAFT WAS RETURNED TO SERVICE AND TEST FLOWN AND NO VIBRATIONS WERE DETECTED.