Accident Overview
A Certified Flight Instructor (CFI) was providing multiengine instruction to a pilot. The flight was in the traffic pattern at approximately 800 feet above ground level (agl) after completing several touch-and-go landings.
Simulated Engine Failure Procedure
The CFI reported that his standard method for setting up practice engine-out landings involved closing the mixture on one engine, allowing the student to control the airplane and simulate feathering the propeller, then returning the mixture to full rich and verifying engine operation. This procedure was typically performed on the downwind leg, and the landing was completed with the simulated inoperative engine at idle.
The Accident Sequence
On the downwind leg, the CFI closed the mixture on the left engine. During the turn from base leg to final approach, the pilot turned the airplane to the left, and airspeed decreased. The airplane then rolled sharply to the left and lost altitude. The CFI responded by reducing both throttles and regained control of the airplane at the moment it collided with the roof of a house. The airplane then bounced across the roof of a second house and came to rest on top of a third house.
Regulatory Guidance
The Federal Aviation Administration recommends that in-flight simulated engine failures at altitudes below 3,000 feet agl be introduced only by reduction of the throttle, not by closing the mixture.
Post-Crash Inspection
A post-crash inspection of the engine and airframe revealed no anomalies that would have prevented normal operation.