What was found
(CAN) DURING APPROACH THE DROOP COMPENSATOR SYSTEM FAILED TO RESPOND AND ENGINE RPM INCREASED AS THE COLLECTIVE WAS LOWERED. PILOT ADJUSTED ENGINE RPM USING THE ELECTRICAL TRIM SYSTEM, (BEEP SWITCH). SUBSEQUENT INSPECTION FOUND THAT THE ENGINE GOVERNOR CONTROL, SAFETY BELL CRANK SHEAR RIVET, HAD SHEARED. NO BINDING COULD BE FOUND IN THE GOVERNOR CONTROL SYSTEM LINKAGES. FAILURE OF THE SHEAR RIVET IS LIKELY THE RESULT OF FATIGUE.