What was found
AIRCRAFT LANDED ON RUNWAY 1 WITH WIND FROM THE NW AT 18 TO 23 KNOTS. AT TOUCH-DOWN, LT MAIN GEAR ROTATED 90 DEGREES AND SKIDDED UNTIL ACFT STOPPED NEAR LT SIDE OF RUNWAY. BOLT AN175-20, BUSHING 5041013-1, NUT AN310-5, AND WASHERS WERE STILL ATTACHED TO UPPER LINK ASSY, P/N 5141005-7. WASHER, P/N 5045018-2, HAD SHEARED THE OUTER PORTION AND ALLOWED NUT, P/N AN310-5, TO PULL THROUGH LOWER LINK ASSY, P/N 5141005-7, LETTING LOWER STRUT/WHEEL TO TURN 90 DEGREES. WASHER, P/N 5045018-2, DID APPEAR TO HAVE PRIOR WEAR. SUBMITTER SUSPECTS POOR PRE-FLIGHT INSP, LANDING TECHNIQUE, AND/OR LACK OF PROPER MAIN.