Accident Sequence
Mechanics at the airport reported that during the takeoff ground roll, the aircraft's right engine backfired and emitted black smoke. The takeoff roll was approximately 80% longer than normal, and witnesses observed the aircraft stagger off the ground, maintaining slow speed and never exceeding 100 feet above ground level. The pilot informed the tower of the need to return to the runway. Shortly after, witnesses saw the aircraft enter a steep left turn, which appeared to result in a stall, and then it crashed into tennis courts.
Investigation Findings
Examination of the wreckage revealed evidence that the right engine had lost power. A modification kit for the fuel injector reference air lines had been incorrectly installed, allowing an unfiltered air source. Spectral analysis of residue from the right engine turbocharger compressor showed the same composition as the alternate air door seal, and traces of this material were found in the fuel injector reference air line. All five occupants were killed.
Probable Cause
The official probable cause is the pilot's failure to attain adequate airspeed before maneuvering (turning) back toward the airport, resulting in a loss of aircraft control. A contributing factor was improper maintenance or installation of a fuel injector reference air line, which allowed contamination of the injectors and loss of power in the right engine.