C421 PLT DURING LNDG HAS THE L MAIN GEAR COLLAPSE AND DEPARTS THE RWY.

Narrative

NIGHT VMC WITH AN 8-10 KT XWIND L TO R FROM THE SW; I LINED UP ON A LONG FINAL APCH TO RWY 32 FROM THE S WITH ROUGHLY A 5 DEG CRAB ANGLE TO THE L. LNDG GEAR DOWN AND LOCKED; FINAL CHK COMPLETE; I CROSSED THE FENCE AND TRANSITIONED TO L WING LOW FOR THE XWIND. ALL INDICATIONS NORMAL I REDUCED THROTTLES; GENTLY FLARED; AND TOUCHED THE L MAIN GEAR WHEEL FIRST WHEREBY AN INSTANT SQUEAL OF THE TIRE SOUNDED FOLLOWED BY AN ABRUPT YAW TO THE L. I INSTINCTIVELY APPLIED R RUDDER; AT WHICH TIME ALL LNDG GEAR WHEELS WERE ON THE RWY; IN AN EFFORT TO KEEP THE AIRPLANE PROPERLY ALIGNED ON THE RWY. FOR A BRIEF MOMENT; THE PULL TO THE L SUBSIDED THEN IMMEDIATELY RETURNED; UNCTLABLE; AND FORCED THE AIRPLANE OFF THE L SIDE OF THE RWY. OFF THE RWY IN THE GRASS THE AIRPLANE SPUN APPROX 120 DEGS FROM RWY HDG AND SLID TO A STOP WITH THE L WING LOWER THAN THE R. I IMMEDIATELY COMMANDED 'GET OUT! GET OUT! GET OUT!' WHEREBY ALL 3 OCCUPANTS IN ADDITION TO MYSELF EXITED THE AIRPLANE THROUGH THE MAIN DOOR. UPON VERIFYING ALL OCCUPANTS SAFELY OUT OF THE AIRPLANE; I SCRAMBLED BACK IN TO CLOSE THE MIXTURE LEVERS AND THROW THE GANG BARS (BATTERY; ALTERNATORS; MAGNETOS). I SECURED THE AIRPLANE; AND LEFT WITH THE OTHERS.