AN ATX FRTR PLT DAMAGED HIS ACFT WHEN HE DRIFTED OFF THE SIDE OF THE RWY.

Narrative

I NOTICED A BIT OF DRIFT TOWARD THE L SIDE OF THE RWY. SMALL CORRECTION RECTRED THE ACFT'S POS. PWR REDUCTION; ROUNDOUT AND FLARE ALL NORMAL. FIRST INDICATION OF TROUBLE WAS AN UNEXPECTED LENGTHY FLOAT TIME. BY THE TIME I NOTICED THE ACFT'S MOVEMENT TOWARD THE L SIDE RWY LIGHTS; I WAS PRACTICALLY ON THE RWY AND AT THE LNDG STALL. MY FIRST REACTION WAS FULL THROTTLE AND HIGHER NOSE UP PITCH. THIS ALLOWED ME TO MISS THE FIRST RWY LIGHT IN MY PATH. I STILL HAD NOSE UP PITCH AND WAS NOW TRYING TO GRADUALLY BANK TO THE R TO REACH THE RWY SURFACE. MY R MAIN WENT THROUGH A SNOW BANK CAUSING MY L MAIN AND NOSEWHEEL TO CONTACT THE SNOW AS WELL. THE AIRPLANE CAME TO A COMPLETE STOP WITH THE R WINGTIP APPROX 25 FT L OF THE L SIDE RWY LIGHTS. NOSEWHEEL WAS BROKEN OFF. NOSE STRUT WAS BENT UNDER BELLY. LOWER COWLING WAS CRUMPLED. PROP BLADES CURLED BACK. PWR HAD BEEN REDUCED WHEN GND CONTACT WAS OBVIOUSLY GOING TO OCCUR. I AM UNSURE OF TOTAL ENG DAMAGE. AFTER THE WRECK; I CHKED MY PLANNING AND FOUND AN ERROR IN MY WT AND BAL COMPUTATIONS. MY INITIAL COMPUTATION GAVE ME A CALCULATED RAMP WT OF 3793 LBS. MY ERROR WAS USING 2283 LBS AS THE BASIC EMPTY WT OF THE AIRPLANE. THIS WAS THE BASIC EMPTY WT OF AN ACFT I HAD RECENTLY EXCHANGED. THE ACTUAL BASIC EMPTY WT WAS 2386 LBS. THIS WAS A DIFFERENCE OF OVER 100 LBS AND PUT THE ACFT 81 LBS OVER LIMIT ON THE TAXI ROLL AND TKOF. THIS EXTRA WT COULD HAVE AND PROBABLY WAS A FACTOR IN MY INABILITY TO CLB OUT ON THE GAR ATTEMPT.