Factual report: Pilots distracted by electrical failure
Cessna 510 Mustang, Carlsbad, Calif., April 19, 2008–According to the NTSB, the probable cause of the Mustang’s runway overshoot was the pilot’s misjudgment
of speed and distance. Factors were his failure to follow the autopilot preflight test- fail checklist and his distraction with a flickering primary flight display screen.
Approaching McClellan-Palomar Airport, the pilot selected vertical speed mode
on the autopilot. On descent, the copilot’s primary flight display began to flicker. Then the left PFD flashed a PFT (preflight test fail) alert, indicating that the autopilot had disconnected. With heavy control forces, the pilot found the electric pitch trim was not operating. The airplane briefly encountered IFR conditions then broke out. On landing, the Mustang was about 15 knots faster than the correct landing speed and touched down halfway down the runway. The pilot made an intentional 180- degree turn to avoid going off the end of the runway and ground-looped. The Mustang came to rest in dirt south of the runway with its main landing gear collapsed. No one was injured in the accident.
The pilot said he never attempted to reset the autopilot, which was designed
for an automatic disengagement when there is a system failure, invalid sensor data or yaw damper failure. The manufacturer’s current emergency procedures checklist states that if the autopilot warning (red PFT warning on the PFD) illuminates, the pilot should reset the associated circuit breaker to clear the fault.