Engine detonation leads to power line collision during checkout flight

1 fatality • Palm Springs, United States of America • Landing (descent or approach)

A modified aircraft experienced severe engine detonation during a local checkout flight, resulting in a collision with power lines shortly after takeoff.

What happened

During a local area flight intended for an aircraft checkout, a pilot encountered significant engine issues shortly after departure. While maintaining a low altitude, the pilot notified the control tower regarding a fuel-related problem. In an effort to address the situation, the pilot attempted to return to the airfield, but the aircraft struck power lines approximately 1.5 miles north of the airport.

Findings

Post-accident inspections of the engines identified that severe detonation had taken place. Although the aircraft had been refueled with 100LL aviation gasoline twice the previous day in preparation for an upcoming trip, subsequent testing of a fuel sample showed no evidence of contamination by jet fuel.

Investigation into the aircraft's mechanical state revealed that the aircraft had undergone modifications, including the installation of turbochargers and higher horsepower engines equipped with manual wastegates. During the examination of the aircraft systems, investigators discovered that the manual wastegates were in a partially closed position. This specific setting is capable of increasing manifold pressure beyond standard limits, as the engines are designed with a maximum restriction of 29.5 inHg.

Probable cause

The engine experienced severe detonation likely caused by increased manifold pressure resulting from the manual wastegates being set in a partially closed position.

Frequently asked questions

What happened in the 1998-10-01 Rockwell Grand Commander 680 accident near Palm Springs, United States of America?

A modified aircraft experienced severe engine detonation during a local checkout flight, resulting in a collision with power lines shortly after takeoff.

Were there any fatalities in the 1998-10-01 Rockwell Grand Commander 680 accident?

The accident was fatal, resulting in 1 fatality.

What aircraft was involved and where did it happen?

The accident on 1998-10-01 involved a Rockwell Grand Commander 680, registration N5YZ, operated by Desert Aircraft Sales, at Palm Springs, United States of America.

What was the probable cause of the accident?

The engine experienced severe detonation likely caused by increased manifold pressure resulting from the manual wastegates being set in a partially closed position.

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