What was found
DURING O/H AND REPAIR CYCLES TO VALVE HOUSINGS, IT WAS NOTICED THAT AN INCREASED RATE OF GOVERNOR BEARING FAILURE IS OCCURRING. A SUBSEQUENT INDEPENDENT ENGINEERING LAB WAS CONTRACTED TO PERFORM AN EVALUATION AND A SUBSEQUENT REPORT WILL FOLLOW (PLEASE DISREGARD ITEM 7 ON THE REPORT AS IT MAY BE A SEPARATE BEARING) FAILURE OF THIS BEARING WHICH SUPPORTS THE SPEEDER SPRING AND FLYWEIGHT SIDE OF THE GOVERNOR RESULTS IN AN OUT OF LIMITS PROPELLER RPM FLUCTUATION WHICH LEADS TO IN-FLIGHT ENGINE SHUTDOWNS. IT IS SUSPECTED THAT THERE MAY BE A MFG FLAW LEADING TO PREMATURE BRINNELLING OF THE BEARING RACES, SPALLING, AND BEARING FAILURE. THESE PROPELLER VALVE HSGS ARE USED ON L-100 AND L-382 AIRCRAFT (CIVIL VARIANTS OF THE C-130).