SMA HAS LNDG GEAR COLLAPSE ON LNDG.

Narrative

ON AN EXTENDED DOWNWIND TO FFL; I EXTENDED ONE NOTCH OF FLAPS AS THE ACFT SPD DECELERATED TO FLAP RANGE. IMMEDIATELY FOLLOWING; I MOVED THE GEAR SELECTOR SWITCH TO THE DOWN POS AND HEARD THE GEAR CYCLE NORMALLY FOLLOWED BY ILLUMINATION OF THE GREEN GEAR DOWN LIGHT (ACFT HAS ONLY 1 GEAR DOWN LIGHT). THE APCH PROCEEDED NORMALLY TO BASE AND FINAL WITH FULL FLAPS EXTENDED AND A NORMAL APCH SPD OF 80 MPH. IT IS IMPORTANT TO NOTE THAT THE GEAR DOWN LIGHT WAS CHKED AN ADDITIONAL 2 TIMES DURING THE APCH AND WAS FOUND ILLUMINATED THROUGHOUT THE APCH. CONTINUING TO THE ROUNDOUT AND FLARE THERE WAS A XWIND FROM THE R SO A SIDESLIP WITH R WING DOWN WAS FLOWN INTO THE FLARE. THE R MAIN GEAR TOUCHED DOWN FIRST FOLLOWED BY THE STALL WARNING HORN. THE L WING SETTLED AND EVENTS PROCEEDED QUICKLY. THE L MAIN GEAR AND NOSE GEAR WERE NOT DOWN AND LOCKED AND R MAIN GEAR FOLDED BACK UP AS THE ACFT SLID STRAIGHT DOWN THE RWY ON ITS BELLY FOR 200-250 FT. ALL ON BOARD EXITED SAFELY AFTER THE ACFT STOPPED. IN SHORT; THERE WAS NEVER ANY INDICATION THAT THE GEAR WAS NOT DOWN AND LOCKED. THE LNDG GEAR/WARNING SYS SIMPLY MALFUNCTIONED CATASTROPHICALLY.