Accident Overview
During a local area aircraft checkout flight, the aircraft remained low and the pilot informed the tower of a fuel problem. The pilot attempted to return to the airport but collided with power lines approximately 1.5 miles north of the airfield.
Aircraft and Modifications
The aircraft had been modified with higher horsepower engines and turbochargers equipped with manual wastegates. The engines were restricted to a maximum manifold pressure of 29.5 inHg.
Preflight Fueling
In preparation for a trip, the aircraft had been fueled twice the day before with aviation-grade 100LL fuel. A postaccident fuel sample tested negative for jet fuel contamination.
Engine Examination
Examination of the engines revealed evidence of severe detonation. During the postaccident inspection of the aircraft systems, the manual wastegates were found partially closed. In this position, the wastegates can provide additional manifold pressure, potentially exceeding engine limitations.
Probable Cause
The official probable cause was stated as the pilot's failure to properly use the manual turbocharger wastegates and to monitor the manifold pressure during takeoff.