Bullard, TX, USA
N8879S
CESSNA 150F
Following a full-stop landing and a back taxi to the runway, the flight instructor and a student pilot planned to conduct a soft-field takeoff to prepare the student for his private pilot test flight. Although there were no witnesses to the takeoff, an automobile dash camera video showed the airplane flying just above tree tops and then entering a right turn. During the turn, the left wing and the nose of the airplane dropped, which was consistent with a stall and an initial spin. The airplane then descended and impacted the ground. The available evidence did not indicate which pilot was flying the airplane at the time of the accident, but it is likely that the student pilot was flying at the time. Postaccident examination of the airplane and engine revealed no anomalies that would have precluded normal operation. The carburetor heat control was found in the off position, which was the correct position for takeoff. The temperature and dew point at the time of the accident were in a range of susceptibility for moderate icing at cruise power settings and serious icing at descent power settings. Although the airplane was at takeoff power when the accident occurred, a partial loss of engine power likely occurred due to carburetor icing, which might have accumulated while the airplane was operating at a lower power setting on the ground before the accident takeoff. The partial loss of engine power resulted in reduced airplane performance and the pilot's inability to maintain adequate airspeed, which then resulted in an exceedance of the airplane's critical angle-of-attack and a subsequent aerodynamic stall.
On August 1, 2017, about 1515 central daylight time, a Cessna 150F, N8879S, impacted terrain following a loss of control during initial climb after takeoff from runway 12 at the Tarrant Field Airport (6X0), near Mount Selman, Texas. The flight instructor received minor injuries and the student pilot received serious injuries. The airplane impacted nose down and received substantial damage to the forward fuselage and wings. The aircraft was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed for the flight, which was not on a flight plan. The flight originated from Tyler Pounds Regional Airport (TYR), Tyler, Texas, about 1445. The flight instructor reported that the flight was to prepare the student pilot for his private pilot test flight. They departed TYR and flew to 6X0, making one full-stop landing followed by a taxi back to the end of the runway for a soft-field takeoff. The flight instructor had no memory of the accident takeoff, although he surmised that there could have been a loss of engine power. An automobile equipped with a dash camera, traveling south on highway 69, east of 6X0, captured the final moments of the flight including the impact. A review of the video, revealed the airplane entering the right frame of the video, just above tree top level. The airplane travels to the left and starts to make a right turn. The wing flaps were not fully retracted, but the amount of deflection could not be determined from the video. During the turn, the left wing and nose of the airplane drop, and the airplane descends into the ground. The airplane struck the ground just east of the highway in a left wing low, nose low attitude, coming to a rest facing north. The airplane was removed from the scene, and a postaccident examination of the airplane under the supervision of Federal Aviation Administration Inspectors was conducted. The wings and empennage were removed during recovery. Many of the control cables were either cut or disconnected at various turnbuckles; however, flight control continuity was established from the cockpit to the flight control surfaces. The flap actuator position corresponded to a 10° flap deflection. Dirt type sediment was observed in the bottom of the fuel strainer bowl along with evidence of corrosion. Fuel system continuity was confirmed from each wing root to the fuel strainer and the fuel selector valve was in the on position. Each fuel tank finger screen was clear of debris. The carburetor heat control was found in the off position. Examination of the engine confirmed compression, valve action of all valves, and spark from both magnetos during engine rotation. The carburetor mounting flange was impact separated from the induction assembly. The carburetor remained attached to the separated flange and the mixture and throttle control cables remained attached to the carburetor. The throttle valve was observed in the full open position and the mixture was full rich. The accelerator pump did not spray fuel into the carburetor throat upon throttle actuation. Disassembly of the carburetor revealed dirt and sediment in the bowl, but no obstruction of the fuel metering port was observed. The accelerator pump had rust on its base. No anomalies were found with respect to the airframe or engine that would have precluded normal operation. The temperature and dew point recorded at the Cherokee County Airport (JSO), about 14 miles south of the accident site were 23° and 21° Celsius, respectively. According to a carburetor icing probability chart published by Flight Safety Australia, the recorded temperature and dew point were in a range of susceptibility for moderate icing at cruise power settings and serious icing at descent power settings.
The partial loss of engine power due to carburetor icing and the pilot's inability to maintain adequate airspeed during the soft-field takeoff, which resulted in an exceedance of the airplane's critical angle-of-attack and an aerodynamic stall.
Source: NTSB Aviation Accident Database
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