On April 29, 1993, a Grumman G-164A (registration N9696) operated by Coates Flying Service, Inc. was involved in an aviation accident near Hamilton, AL. Investigators recorded the probable cause as: The engine failure was caused by fuel exhaustion resulting from a higher-than-expected fuel burn rate required to maintain a ground speed of 100 knots. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot was forced to perform an emergency landing in a forested area after the engine quit due to fuel exhaustion during a ferry flight.
What happened
During a ferry flight, approximately one hour and forty-two minutes into the trip, the engine of the aircraft stopped running. The pilot reported that the failure was caused by fuel exhaustion. Following the loss of power, the pilot performed a forced landing into a forested area, where the aircraft collided with trees and terrain. At the start of the flight, the pilot had calculated that there were approximately two hours and twenty minutes of fuel available on board.
The investigation
The investigation focused on the discrepancy between expected fuel consumption and actual usage. While the operator provided fuel burn data from previous flights, that data was based on a ground speed of approximately 78 knots using 2,000 RPM and 28 inches of manifold pressure. However, investigators determined that the average ground speed during this specific accident flight was approximately 100 knots. This higher speed would have necessitated a higher engine power setting, thereby increasing the rate of fuel consumption. Additionally, an examination of the aircraft wreckage showed no evidence of any fuel leak.
Probable cause
The engine failure was caused by fuel exhaustion resulting from a higher-than-expected fuel burn rate required to maintain a ground speed of 100 knots.