Overview
A flight instructor and a pilot receiving instruction were conducting a simulated single-engine approach when the aircraft landed with the landing gear retracted, resulting in substantial damage.
Sequence of Events
According to the flight instructor, the pilot receiving instruction was performing a simulated single-engine approach. The instructor set the simulated failed engine to 15 inches of manifold pressure to facilitate easier communication with the pilot. The aircraft's landing gear warning horn is designed to sound if manifold pressure is set below 14 inches. The instructor did not verify that the landing gear was down and locked by checking the three green extended lights.
Just before landing, the instructor heard an audible alarm. He attributed this sound to the stall warning horn, though it was actually the landing gear warning horn. The pilot receiving instruction reported no recollection of hearing any audible alarm. The aircraft subsequently touched down with the landing gear retracted.
Damage
The accident resulted in substantial damage to the airplane's engines.
Instructor Report
The flight instructor reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.