What was found
AFTER COMPLIANCE WITH SB M20-282 AND THE CORRESPONDING SI 102000-1901 REV 2 THE NO-BACK CLUTCH SPRING MECHANISM WAS ALLOWING THE ACTUATOR TO (BACK UP) UNDER NORMAL LOADS. IT WAS FOUND THAT EXCESSIVE FRICTION BETWEEN THE INPUT/DRIVE GEAR ASSY AND THE OUTPUT/DRIVEN GEAR ASSY CAUSES THEM TO (LOCK) TOGETHER AND THEREFORE ROTATE SIMULTANEOUSLY. UNDER THIS CONDITION THE NO-BACK CLUTCH SPRING WILL SLIP AND NOT LOCK PROPERLY. TWO CAUSES OF THE EXCESSIVE FRICTION WERE NOTED. IF THE POINT OF CONTACT IS A THE LARGER DIAMETER HUBS INSTEAD OF THE SMALLER DIAMETER GEAR SHAFTS. IF GEAR SHAFT ASSY IS PRELOADED TO THE MAX ACCEPTABLE LIMIT AS DEFINED IN THE ABOVE TWO BULLETINS.