On November 20, 1998, at 1401 hours Pacific standard time, a Piper PA-30B, N7933Y, sustained substantial damage while attempting a simulated single engine landing at the Camarillo, California, airport. The pilot/owner was operating under the provisions of 14 CFR Part 91. The instructional flight departed Van Nuys, California, about 1300. The private, multiengine rated pilot sustained minor injuries; the instructor pilot was not injured. Visual meteorological conditions prevailed and no flight plan was filed. The pilot was seeking a commercial multiengine rating; he and the instructor had flown three previous flights together. After departure they proceeded to the practice area and conducted their training maneuvers for 10 to 15 minutes, and upon completion, they turned towards Camarillo for practice landings. En route to Camarillo the instructor reduced power on the right engine to simulate an engine failure. The aircraft entered the traffic pattern for runway 26. The pilot stated he felt the wind was strong. He thought he was wide turning base to final because of the wind, but that he was still in a good position to land. The instructor stated the aircraft was angling toward the runway on final but was in position to make a normal landing. The pilot flew the approach 10 miles per hour over the recommended approach speed of 90 miles per hour. He added 10 degrees of flaps. As the pilot was about to initiate his flare he became concerned that the aircraft would touchdown short of the displaced threshold. He added power to the left engine. The airplane immediately yawed to the right; the nose of the aircraft rose up and then fell down. The right wing struck the ground and the aircraft came to rest at the side of the overrun, short of the displaced threshold. Both sets of propeller blades were bent and both engine cowlings exhibited crush damage. The empennage, fuselage, and wings were buckled and crushed. The pilot had the airplane retrofitted with shoulder harnesses a few years prior to the accident and felt they were a positive factor regarding injuries. The pilot had 800 hours in this make and model. The instructor had a total of 56.6 hours in multiengine aircraft; 2.3 were in this make and model.