What happened
On September 26, 2015, at 12:22 central daylight time, a Zodiac CH 601 HD aircraft, registration N401, crashed in a wooded area near St. Charles Airport (LS40) in Ama, Louisiana. The flight was a local personal trip under Part 91 regulations, and no flight plan had been filed.
GPS data from a Garmin Aera 500 recovered from the wreckage showed the aircraft began its takeoff roll on runway 17 at 12:21:18. During the takeoff roll, the aircraft reached a maximum groundspeed of 84 knots. After departing, the groundspeed fluctuated between 45 and 96 knots as the pilot turned to a southwesterly heading. At 12:22:32, the aircraft made a right turn toward the northwest. The final recorded GPS data point at 12:22:37 indicated the aircraft was at an altitude of 66 feet with a groundspeed of only 15 knots.
The aircraft struck the ground in an 80-degree nose-down attitude. The wreckage was located the following day near the departure end of runway 17. The pilot sustained 1 fatal injury.
The investigation
Investigators examined the engine and airframe for mechanical failures. The engine, a 65-horsepower Lycoming O-235-C1, showed no mechanical malfunctions or failures that would have prevented normal operation. While the propeller assembly showed signs of little to no rotation at the time of impact, the engine's internal components, including the cylinders and valve train, were found to be in functional condition.
Examination of the fuel system revealed the fuselage fuel tank was empty and partially crushed. A hole was noted in the fuel strainer/gascolator screen, and a bolt was found obstructing the opening of a fuel vent tube. However, no mechanical failure was identified as the definitive cause of a power loss.
An autopsy of the pilot revealed atherosclerotic cardiovascular disease, including 60% narrowing of the left anterior descending coronary artery and a scar from a previous heart attack. While these conditions could have led to an acute cardiac event, investigators could not definitively determine if medical incapacitation contributed to the accident, noting that the evidence of engine power loss did not specifically support an incapacitating event.
Findings
- The aircraft's impact attitude and wreckage configuration were consistent with a left spin following an aerodynamic stall.
- The pilot failed to maintain sufficient airspeed and exceeded the aircraft's critical angle of attack.
- The investigation could not determine the specific reason for the loss of engine power.
- Weather conditions at the time were conducive to serious carburetor icing at descent power, though the aircraft was operating at takeoff power.