Flight Information
The airplane, flown by a commercial pilot and carrying three passengers, departed in day visual meteorological conditions for a local flight over rugged mountainous terrain. The purpose of the flight was to meet up with a motor glider and make "flybys" of the glider. The glider pilot was giving a ride to the airplane pilot's friend.
Events Leading to Accident
The glider pilot reported that the airplane made two passes by the glider. During the second pass, the airplane was in coordinated flight with flaps up, either level or descending slightly. The glider was at an altitude of about 8,900 feet with a ground speed of about 57 knots. The glider pilot lost sight of the airplane as it proceeded north into a cirque or bowl formed by a mountain range (peak elevation about 9,600 feet) running north to south and a transverse range (peak elevation 8,916 feet) running west and then hooking south. The glider pilot and passenger did not witness the accident. About 90 seconds later, the glider entered the bowl and the pilot executed a left 180-degree turn at altitudes of 9,100 to 9,200 feet, encountering an air mass sinking about 100 to 200 feet per minute.
Passenger Account
The surviving passenger, seated in the left rear seat, reported that as the airplane made the second pass on the glider, the stall warning indicator sounded. The pilot dropped the nose to level out, and the stall warning indicator stopped sounding. The passenger then heard a high-pitched whine similar to a noise heard during preflight check, which he thought was the flap motor, but he saw that the flaps were not moving. He could not see the pilot moving the flap control, and neither the pilot nor the other passengers made comments about the flaps. The pilot then initiated a descending left turn. During this turn, the pilot looked over his shoulder and said, in a normal tone of voice, "hang on, we might get a couple of trees on this one." It was about 10 to 15 seconds from when the stall warning horn stopped sounding until impact with trees.
Post-Accident Examination
Distribution of wreckage indicated the airplane impacted trees on the transverse ridge at an elevation of 8,553 feet on a southwesterly heading and traveled about 360 feet before coming to rest. Examination of the airframe and engine revealed no evidence of discrepancies that would have prevented normal operation. The flaps were found in the retracted position. Functional testing of the flaps was precluded by impact and fire damage. The pilot who flew the airplane just prior to the accident flight stated that she experienced no problems and that the flaps worked normally. About 11 days after the accident, the surviving passenger reported no problems during runup or takeoff. About 8 weeks later, he told his attorney that he recalled the pilot mentioned before takeoff that the flaps were not working.