THE PLT WAS RETURNING TO LAND AFTER HAULING SKYDIVERS. HE RPRTD THAT WHILE ON A SHORT FINAL APCH TO LAND ON RWY 31 WITH 20 TO 30 DEG OF FLAPS EXTENDED, THE ACFT ENTERED A HIGH SINK RATE IN GUSTY WIND CONDITIONS. HE SAID THAT HE LOWERED THE NOSE TO INCREASE SPEED & THAT HE PLANNED TO ARREST THE SINK RATE IN THE FLARE, BUT THEN 'THE BOTTOM FELL OUT' & THE ACFTCOLLIDED WITH THE GROUND IN A NOSE LOW ATTITUDE. THE FLT MANUAL RECOMMENDED THAT IF THE RWY LENGTH PERMITTED, CROSSWIND LANDINGS SHOULD BE PERFORMED WITH THE FLAPS RETRACT. THE MANUFACTURER ESTIMATED THAT 560 FT WOULD HAVE BEEN REQUIRED TO LAND THE ACFT ON A HARD SURFACE WITH NO WIND & 40 DEG OF FLAPS. THE RWY LENGTH WAS 2800 FT. THE PLT RPRTD THE WIND WAS VARIABLE FROM 240 TO 270 DEG WITH GUSTS TO 20 KTS. APRX 20 MI SOUTHEAST AT SHAW AFB, THE 1655 EDT WIND WAS RPRTD TO BE FROM 260 DEG AT 20 GUSTING 28 KTS.