Accident Sequence
The pilot aborted the first takeoff because the engine was running rough. After performing a run-up and determining that the engine seemed normal, the pilot returned for another takeoff. Following liftoff, the engine began to lose rpm, and the pilot had difficulty gaining altitude. At about 100 feet above ground level, the pilot turned toward a grassy area parallel to the runway. The aircraft collided with trees and came to rest upright on the ground.
Post-Accident Examination
The Safety Board conducted a run-up of the engine. No abnormal sounds were noted at 2,000 rpm, but at full throttle, the engine began to run rough and the fuel pressure gauge indicated at or near the low scale.
Examination of the fuel system revealed that the aircraft has a separate fuel shutoff valve independent of the fuel selector. The shutoff valve is operated by a control knob near the pilot's right knee. It was noted that the fuel shutoff valve follower handle was partially closed at the valve while the control knob was in the ON position. The firewall-mounted clamp that secures the cable housing was loose, and the cable housing was able to slide back and forth in the clamp. The valve could be hand actuated from the on to off position without any significant movement of the control knob.
Maintenance History
Airworthiness Directive 70-24-04 concerning the fuel shutoff valve was complied with in 1984 by installation of Cessna Kit No. SK117-10. The fuel shutoff control knob is required to be safetied in the 'on' position. No safety wire was in place, and no hole was drilled in the subject knob to accommodate the wire.
Additional Engine Tests
With the fuel shutoff valve properly configured and in the full on position, another engine run-up was conducted to full power with and without the auxiliary fuel pump.