BFO84FU002

The plt of the ultralight vehicle, a student, was in radio contact with his instructor thru use of a portable hand-held UHF transceiver. About 10 min after takeoff, the instructor asked him to return to the airstrip for a practice power off landing. During the apch, when the vehicle was about 1/2 mi from the strip at 600 to 800 ft AGL, the instructor asked him to reduce the power to idle. The instructor had heard the power reduction to about 50% when he observed the nose of the vehicle pitch down. From his position, the vehicle appeared to flip over, similar to an outside loop, but with no loss of alt. (The operator believed there might have been a rapid nose down, then nose up pitch which appeared to be a tumble.) Immediately after the vehicle returned to an upright position, the wings foldedupward, then the ultralight entered a descent & crashed. No evidence of fatigue or pre-accident malfunction was found. Apathological exam revealed evidence of coronary artery disease & angina. Medical examiner suspected physical impairment.