What was found
WHEN LANDING GEAR WAS SELECTED DOWN, THE GEAR FAILED TO EXTEND NORMALLY. LANDING GEAR CIRCUIT BREAKER HAD TRIPPED. MANUAL GEAR EXTENSION PROCEDURE WAS USED. PILOT MADE AN UNEVENTFUL LANDING. INSPECTION REVEALED THAT THE LANDING GEAR MOTOR RELAY HAD HIGH RESISTENCE, CAUSING THE TIME-RELAY CIRCUIT TO OPEN THE CIRCUIT BREAKER.