What was found
NLG COLLAPSED ON LANDING, AFT END OF NOSE GEAR ACTUATOR ATTACHES TO BRACKET. THIS IS RIVETED THRU FIREWALL TO NOSE GEAR MOUNT FITTING. RIVETS WORKED FROM FORWARD/AFT PUSHING MOTION OF NOSE GEAR ACTUATOR, ELONGATING, THEN SHEARING OFF RIVETS. ACTUATOR WENT TO FULLY EXTENDED POSITION, BUT DID NOT CAUSE NOSE GEAR DRAG LINK TO GO TO OVER-CENTER POSITION, AS SHEARED OFF RIVETS PREVENTED IT FROM GETTING GOOD PUSH, AND OVER-CENTER ACTION OCCURING. NOSE GEAR COLLAPSED WHEN WEIGHT OF AC WENT ONTO NON-OVER CENTER DRAG LINK. ELONGATED AND SHEARED OFF SITUATION GOES UNDETECTED AS RIVETS ARE COVERED ON SIDE OF TUNNEL BY MATERIAL GLUED TO TUNNEL WHERE CO-PILOTS LT FOOT WOULD NORMALLY BE. NEED AD