What happened
Following several unsuccessful attempts to start the engines, a mechanic removed the 'P' leads on all magnetos. This action made it impossible to complete the required run-up checks. Shortly after the landing gear was retracted, the aircraft's velocity decreased. At approximately 200 feet MSL, the pilot performed a forced landing into a plowed field. The 6 male passengers on board were not injured. Passengers reported hearing the stall warning prior to the impact.
The investigation
Investigators confirmed engine continuity and performed differential compression checks. The results showed that four cylinders on the left engine and five cylinders on the right engine were below 60 PSI.
An examination of the ignition system revealed that the points on all magnetos were burned, and the left magneto on each engine failed to fire. All spark plugs showed evidence of wear and deposits in the electrodes. Specific failures were noted in the bottom plugs of the left engine (cylinders #3 and #5) and the right engine (cylinders #1, #3, #4, #5, and #6), as well as the top plugs of the right engine (cylinders #5 and #6).
Additionally, the fuel control unit throttle body on the left engine was found to be unclamped at the turbocharger. At the time of the event, the aircraft was carrying 120 gallons of fuel, and the density altitude was calculated at 2,600 feet.