BEECH 58TC — Mesa, CO

What happened

The pilot departed on a personal flight that was the first flight after completion of the airplane’s most recent annual inspection. Recorded air traffic control communications revealed that pilot had climbed through 11,000 ft for 14,000 ft. The flight track showed that, after the airplane reached 14,000 ft, it descended about 1,000 ft, climbed to 15,000 ft, and then descended rapidly toward terrain. The airplane impacted a rocky mountainside about 25 nautical miles north of the departure airport.

The wreckage debris path was about 30 ft long and consisted mostly of paint chips, shards of windscreen, various small debris, and a large outboard section of the right wing that had separated on impact. The empennage was distorted to the left and remained partially attached to the rear fuselage. The bottom of the airplane exhibited impact damage and scoring from the rocky terrain. The left engine was mostly separated from the leftwing nacelle, and the right engine remained attached to the right-wing nacelle. All six propeller blades were relatively undamaged and did not exhibit leading-edge damage or scoring, which was consistent with minimal, if any, rotation during impact. The right engine compartment, propeller blades, and right-side nose compartment were covered in a layer of engine oil. The engine throttle levers were found near the idle position, and the mixture and propeller control levers were found near the forward position. The pilot’s seatbelt and shoulder harness were not latched during the accident and the pilot was ejected from the airplane.

On the right engine, the oil line from the turbocharger wastegate control valve outlet to the inlet side of the turbo pressure controller was loose at the wastegate outlet end. Also on the right engine, the propeller governor had fractured near the mounting base and remained attached to the mounting pad, but three of the four mounting nuts were loose. According to a discrepancy in the maintenance records from the most recent annual inspection, oil was found around the right engine propeller governor. Although the corrective action noted in the maintenance records was to remove the left engine propeller governor and install a new gasket, the mechanics indicated that the reference to the left engine was likely an inadvertent error and that they actually replaced the gasket on the right engine. However, the right engine propeller governor was not properly reinstalled. It is also likely that the turbocharger oil line was not properly tightened. These loose connections likely resulted in a loss of oil during the flight, which led to a loss of engine power.

The pilot likely experienced difficulty handling the airplane during the emergency and lost control of the airplane.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.