Cessna 150L N1364Q accident near Columbia, California

Probable cause

The flight instructor's decision to attempt takeoff with an engine discrepancy and subsequent failure to abort takeoff when the airplane did not attain adequate airspeed during the initial climb, resulting in an aerodynamic stall. Contributing to the accident was the partial loss of engine power.

NTSB analysis

The flight instructor reported that the student pilot had recently purchased the airplane and that they intended to test fly it within the traffic pattern. Prior to departure, he noted that the wind was about 10-15 knots and favored a 2,600-foot-long turf runway. The instructor stated that he initiated a short field takeoff by holding the brakes, using 10 degrees of flaps, and applying full throttle. He recalled that the engine only produced 2,050 rpm, and that he expected the rpm to increase as he released the brakes. During the takeoff roll, the instructor felt that the tall grass slowed the acceleration of the airplane before it lifted off the ground at 55 miles per hour. He lowered the nose to gain airspeed in ground effect, but the airplane was not accelerating. Due to upward sloping terrain with trees and power lines in the flight path of the airplane, he turned left to avoid the obstacles. During the turn, the angle of bank increased due to a wind gust and the airplane stalled, entered a spin to the left, and impacted the ground in a nose low attitude. Examination of the airframe revealed no anomalies. Examination of the engine revealed that the number two cylinder top and bottom spark plugs were fouled with carbon deposits. These spark plugs would not have fired, resulting in a loss of power from the number two cylinder. The aircraft owner's manual states that during the initial takeoff phase the pilot should verify full throttle operation and that the engine should run smoothly and turn approximately 2,500 to 2,600 rpm with carburetor heat off.

Text from the NTSB. Open the NTSB docket for LAX08LA108 for the full record.