What was found
(CAN) CREW SELECTED GEAR DOWN FOR LANDING. NOSE AND RT MAIN INDICATED LOCKED DOWN. LT MAIN EXTENDED BUT DID NOT INDICATE A LOCKED POSITION. ON TOUCHDOWN LT MAIN COLLAPSED. VISUAL INSPECTION OF LANDING GEAR AND DRAG BRACE ASSY REVEALED THE DRAG BRACE DOWNLOCK HOOK FAILED. THIS HOOK HOLDS THE DRAG BRACE IN THE LOCKED DOWN POSITION AND ALSO ACUATES THE DOWN POSTION MICROSWITCH FOR THE COCKPIT INDICATION AND TERMINATES THE HYD MOTOR AND PUMP OPERATION.