WPR18LA166 · Cessna 421C C

During takeoff on a night aerial observation flight, the pilot reported that the airplane did not accelerate adequately, and he chose to abort the takeoff. The airplane continued off the end of the runway and came to rest in a field about 750 ft past the departure end, resulting in substantial damage to the wings and fuselage. Examination revealed that the left engine turbocharger compressor air duct was disconnected from the throttle body. The right engine's engine-driven fuel pump was contaminated with water and debris and would not produce normal pressures and flow; however, whether these anomalies were present at the time of the accident or occurred as a result of or after the accident could not be determined. There were no other anomalies observed that would have precluded normal engine operation. Review of performance information revealed that, given the airplane's weight and atmospheric conditions at the time of the accident, the pilot had adequate runway available to accelerate the airplane to a decision speed, abort the takeoff, and stop on the remaining runway. Airport surveillance video revealed that the pilot did not activate the pilot-controlled runway lighting before takeoff, and tire skid marks on the runway were consistent with heavy braking within the last 200 ft of the runway's paved surface. The circumstances of the accident are consistent with the pilot's delayed decision to abort the takeoff. The pilot's failure to activate the runway lighting system before takeoff likely contributed to the accident by reducing his ability to judge the airplane's acceleration with respect to the runway distance remaining and abort the takeoff in a timely manner upon recognizing an anomaly.

Verbatim NTSB analysis and probable cause from the NTSB dataset