What happened
During the descent phase of the flight, the aircraft's right engine experienced a sudden loss of power. In response, the pilot feathered the propeller and notified Air Traffic Control of the situation. While the crew was in the process of diverting to an alternate airport, the left engine also failed. The pilot attempted to restore power to the left engine by cycling the boost pump between high and low settings, but these actions failed to resolve the issue. The pilot did not feather the left engine's propeller.
The aircraft ultimately came to rest on an overpass that was currently undergoing construction. Following the impact, structural damage to the airframe resulted in a fuel leak, though it was noted that the aircraft had sufficient fuel remaining at the time of the incident.
Findings
An investigation into the right engine failure revealed that a flexible duct connecting the turbocharger to the plenum chamber had separated because of a loose clamp. During subsequent engine testing, it was observed that the induction air hose could be pulled away, and the engine ran poorly due to an excessively rich mixture. While the right engine's failure was linked to this mechanical issue, investigators were unable to determine the specific reason for the power loss in the left engine.