Accident Details
A private pilot with 300 hours of flight experience reported that the airplane entered an un-commanded nose-down pitch and banked to the left while established on final approach to runway 16. The pilot and passenger were seriously injured in the subsequent accident.
Engine Examination
Post-accident examination of the 180-horsepower engine did not reveal any mechanical anomalies that could have prevented normal engine operation. The fuel cells were breached; however, according to the operator, the airplane had departed with a full load of fuel. The engine tachometer indicated a flight duration of 36 minutes.
Weather and Icing Conditions
A weather reporting station located 30 miles south of the accident site reported winds from 120 degrees at 9 knots, gusting to 14 knots at the time of the accident. An icing probability chart indicated that the weather conditions were favorable for the probability of "serious" carburetor icing at glide power. Examination of the airplane and engine revealed that the carburetor heat control was in the "off" or "cold" position.
Injuries
Both the pilot and the passenger sustained serious injuries.