Incident Overview
Shortly after leveling off at 14,000 feet, the left engine of a twin-engine airplane ceased operating. The pilot initiated a diversion to Tampa, Florida. Approximately 34 minutes later, the right engine also lost power. During the subsequent forced landing, the airplane collided with the roof of a covered sidewalk and then struck trees.
Left Engine Examination
A teardown inspection of the left engine revealed that the seal between the exhaust flange and the turbocharger had not been installed. Additionally, a bolt clamp was found to be only finger tight. The absence of the seal allowed heat to melt the insulation on the wiring harness and the magneto grounding leads, grounding both 'p' leads.
Right Engine Failure Circumstances
The pilot reported that after losing the left engine, he initiated a crossfeed from the left fuel tank to the right engine. After approximately 20 minutes of single-engine flight in this configuration, the right engine also stopped.
Flight Manual Guidance
The airplane's flight manual explicitly states that in the event of one engine failure, the pilot should land as soon as possible. Furthermore, the manual warns that when operating on one engine with crossfeed active, absolutely coordinated flight must be maintained to prevent the fuel pickup tube in the tank from becoming unported when the tank is not full.
Probable Cause (Official Findings)
The inflight failure of the left engine was caused by inadequate maintenance and inspection by company maintenance personnel, resulting in heat-damaged magneto leads due to a missing exhaust flange-to-turbocharger seal. The inflight power loss of the right engine was caused by the pilot's failure to follow the procedures in the airplane operating handbook and land as soon as possible, leading to fuel starvation of the right engine. Darkness was a related factor.