SMA TWIN'S GEAR COLLAPSES ON LNDG PROC ROLLOUT ON TOUCH AND GO. ACFT DAMAGED.

Narrative

ON JUN/XX/93 AT APPROX XY40 PM LCL TIME; I ARRIVED AT GRAND AIRE IN MONROE; MI; FOR THE PURPOSE OF RECEIVING FLT INSTRUCTION IN AN SMA TWIN. A CFIIME; HAD MET US AT THE AIRPLANE AND AFTER I HAD COMPLETED MY NORMAL PREFLT INSPECTION WE DISCUSSED WHAT WOULD BE COVERED DURING THE LESSON. THE LESSON WOULD START WITH A COUPLE OF NORMAL TKOFS AND LNDGS THEN WE WOULD COVER SIMULATED ENG FAILURE PROCS. THE FIRST 2 NORMAL LNDGS WERE TOUCH-AND-GO'S AND WERE COMPLETED WITHOUT INCIDENT. THE THIRD LNDG WAS WITH A SIMULATED ENG FAILURE AND WAS COMPLETED TO A FULL STOP WITHOUT INCIDENT. THE FOURTH AND FIFTH LNDGS WERE ALSO SIMULATING AN ENG FAILURE; HOWEVER; THESE WOULD BE TOUCH- AND-GO'S. THE FOURTH LNDG WAS ALSO COMPLETED WITHOUT INCIDENT. DURING THE FIFTH APCH AND LNDG THE WHEELS TOUCHED DOWN WITHIN THE TOUCHDOWN ZONE ON THE RWY AND THERE WAS NOTHING UNUSUAL NOTED. HOWEVER; WHILE THE ACFT WAS ROLLING DOWN THE RWY; STILL DECELERATING; AT APPROX 60 MPH AND 300-500 FT BEYOND THE TOUCHDOWN POINT; I NOTICED WHAT FELT LIKE THE L MAIN WHEEL HAD RUN OVER A POTHOLE. A SPLIT SECOND AFTER THIS THE L SIDE OF THE ACFT DROPPED SHARPLY AND STRUCK THE GND. APPROX 1 SECOND LATER THE NOSE AND R SIDE COLLAPSED AS WELL. THE ACFT SKIDDED DOWN THE RWY COMING TO A STOP IN BTWN THE CTRLINE AND THE R RWY EDGE LINE. AFTER A COMPLETE STOP WE IMMEDIATELY EVACED THE ACFT AND NO INJURIES WERE SUSTAINED.