What was found
PILOT REPORTED THAT ON MLG EXTENSION THE CREW HEARD THE MOTOR RUN FOR APPROX 15 SECONDS THEN THE CB NEXT TO THE GEAR HANDLE POPPED. RAN CHECKLIST & MANUALLY EXTENDED GEAR, ALL INDICATIONS WERE NORMAL. REPLACED THE RT MLG UPLOCK SWITCH & RIGGED IAW TC 1900-3260.00, ALL OPERATIONS CHECKED GOOD.