On May 9, 1997, approximately 1100 mountain daylight time, an Aeromot AMT-200 powered glider, N757DM, sustained substantial damage during a simulated forced landing at Vance Brand Airport, Longmont, Colorado. The commercial pilot/flight instructor and his student were not injured. The flight was operating under Title 14 CFR Part 91 when the accident occurred and no flight plan was filed. Visual meteorological conditions prevailed. According to the flight instructor, the student was flying and they had departed runway 29 at Vance Brand and were on a departure crosswind when he pulled the engine to idle to simulate an engine failure. The student set up for a landing on runway 11 and at approximately 3 to 5 feet above the ground at 55 knots, the student, instead of flaring for landing, put the stick full forward. The motor glider impacted the runway and sheared off the main landing gear. The aircraft slid down the runway and came to a stop. According to Thomas Brenza, of Enchantment Aero Services, who conducted repairs to the aircraft, the following repairs were accomplished: 1. Replace left and right main landing gear. 2. Replace left and right brake lines. 3. Repair propeller hub and replace propeller blades. 4. Repair finish crack in wing leading edge forward of the right main landing gear. 5. Repair puncture in right lower wing skin aft of landing gear and repair finish damage. 6. Repair finish cracks at inboard end of right aileron on lower left wing skin. 7. Repair delamination on right wing aft spar at root. 8. Inspect aileron hinge areas, both wings. 9. Inspect lift pins and spar pins, both wings. 10. Repair delamination and finish damage on lower left wing skin aft of main landing gear. 11. Repair finish cracks in left lower wing skin at inboard corner of aileron.