The pilot reported that, on short final, the airspeed was about 65 to 70 knots with full flaps, and he observed the 2 light precision approach path lights indicating 2 white lights. The left wing dropped, and he did not hear the stall warning horn. The left main landing gear touched down hard, the right main landing gear collapsed, and the airplane veered off the runway to the right. The pilot reported that the airplane hit an "air pocket" and crashed. A witness, located on the ramp, observed the accident airplane head-on coming in very low and slow. He saw the airplane aerodynamically stall and the right wing dropped. The right wing impacted the ground, followed by the right landing gear and then the nose landing gear. The landing gear assemblies separated from the airplane which skidded to an abrupt halt. The airplane sustained substantial damage to both wings. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. The pilot did not submit the NTSB Form 6120.1 Pilot/Operator Aircraft Accident/Incident Report.