What was found
(CAN) UPON TAKEOFF THE CREW REPORTED THAT THE RT GEAR WOULD NOT REMAIN LOCKED. ACFT RETURNED TO BASE AND UPON MX INSPECTION IT WAS FOUND THAT THE UP-LOCK HOOK BEARING AND ATTACHING HARDWARE WERE MISSING. IT WAS ALSO NOTED THAT THE UP-LOCK HOOK SHAFT ATTACH POINTS HAD BEEN MARRED. THIS LEADS US TO BELIEVE THAT THE BEARING WAS INSTALLED AND EITHER THE BEARING OR BOLT FAILED. FAILED PARTS WERE REPLACED - GEAR SWINGS CARRIED OUT AND ACFT RETURNED SERVICE.