What was found
LANDING GEAR MOTOR WOULD TRIP CIRCUIT BREAKER DURING ALL ATTEMPTS AT LOWERING LANDING GEAR. EMERGENCY PROCEDURES FOR LANDING GEAR EXTENSION FAILURE AND MANUAL GEAR EXTENSION UNSUCCESSFUL RESULTING IN A GEAR-UP LANDING. ON INSPECTION OF LANDING GEAR COMPONENTS AND ATTEMPT TO LOWER THE LANDING GEAR ON THE GROUND, LANDING GEAR MOTOR CONTINUED TO TRIP THE CIRCUIT BREAKER EVEN AFTER BEING RESET. IT WAS OBSERVED THAT THE MLG ACTUATOR ARMS WENT OVER-CENTER. ARMS WERE PRIED APART TO MANUALLY EXTEND THE GEAR. IT IS SUSPECTED THAT THE RELAY IN THE LANDING GEAR MOTOR IS DEFECTIVE AND CAUSED THE LANDING GEAR EXTENSION FAILURE DUE TO ITS INABLILITY TO ACT AS A BRAKING MECHANISM FOR THE MLG ACTURATOR ARMS AND THE SUBSEQUENT OVER-CENTER SITUATION LOCKING THE ARMS AND PREVENTING A SUCCESSFUL LANDING GEAR EXTENSION.