C-402 LEFT MAIN GEAR COLLAPSED AFTER TOUCHDOWN; AND THE PLT WAS UNABLE TO MAINTAIN DIRECTIONAL CONTROL. THE ACFT EXITED THE RWY; CAUSING THE RIGHT MAIN TO COLLAPSE.

Narrative

AFTER COMPLETING THE LNDG CHKLIST; I WAS CLRED TO LAND ON RWY 14 BY THE TWR. 3 GREEN WAS OBSERVED BY ME INDICATING THAT ALL THE GEAR WERE DOWN AND LOCKED. NO HORN WAS RINGING. MY APCH WAS NORMAL AND STABILIZED AT 120 KTS. AT TOUCHDOWN IN THE FLARE AT 95 KTS THE 2 MAIN GEAR TOUCHED DOWN ON THE RWY; THEN I LOWERED THE NOSEWHEEL ON THE RWY. AFTER THE NOSEWHEEL TOUCHED ON THE ROLLOUT ON THE RWY; MY L GEAR COLLAPSED CAUSING THE ACFT TO VEER L ABRUPTLY; CAUSING THE ACFT TO LEAVE THE RWY. BRAKES WERE APPLIED TO TRY MAINTAINING DIRECTIONAL CTL BUT WERE NOT EFFECTIVE. THE AIRPLANE CAME TO REST ON THE L SIDE OF RWY 14. THE MIXTURES WERE PULLED IMMEDIATELY TO SHUT DOWN THE ENGS AND THE SHUTDOWN CHKLIST WAS PERFORMED. AFTER EXITING THE ACFT; I OBSERVED DAMAGE TO BOTH PROPS OF THE ACFT. IT WAS RESTING ON ITS BELLY. THE R GEAR ALSO COLLAPSED AFTER THE CHAIN OF EVENTS. AFTER VACATING THE ACFT; EMER PERSONNEL CAME TO THE SCENE. THERE WERE NO INJURIES TO MYSELF AS A RESULT OF THIS INCIDENT. I WAS THE SOLE OCCUPANT IN THE ACFT. NO DAMAGE WAS OBSERVED TO THE CARGO THAT WAS ON BOARD THE ACFT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THAT MAINT INSPECTION REVEALED THE DOWNLOCK MECHANISM FOR THE LEFT MAIN GEAR FAILED AFTER A TOUCHDOWN. THE RIGHT GEAR SUBSEQUENTLY COLLAPSED FROM THE SOFT TERRAIN WHEN THE ACFT LEFT THE RWY.