What was found
(CAN) ON TOUCHDOWN CREW FELT LEFT GEAR COLLAPSE & HEARD PROP BLADE STRIKING RWY.GO AROUND COMPLETED, BUT ON SUBSEQUENT LDG GEAR WAS NOT LOCKED DOWN LEFT MAIN GEAR PIVOTED REARWARDS ALLOWING LEFT WING TIP & BLADES OF LEFT PROP TO CONTACT GROUND. A/C STOPPED 50 TO 100 FEET OFF RWY. BOTH LEFT MAIN GEAR DRAG BRACE AFT LOWER LINKS HAD FAILED. LAB ANALYSIS FOUND BRACES FAILED AS A RESULT OF OVERLOAD FORCES IMPOSED BY A PROBABLE HARD LANDING.