Piper PA-25-235 N8808L accident near Boulder, Colorado

Probable cause

The pilot's failure to adequately monitor the airplane's actual fuel consumption rate, which resulted in a total loss of engine power due to fuel exhaustion.

NTSB analysis

The pilot reported that the accident occurred during his fifth glider aero-tow flight since the airplane had last been refueled. He stated that the aero-tow and glider release were uneventful. However, as he was returning to the departure airport, the engine began to run intermittently before it eventually experienced a total loss of engine power. During the subsequent forced landing, the airplane became entangled with a chain-link fence and impacted a road before it slid into a drainage ditch.

A postaccident examination of the airplane's single fuel tank established that it was undamaged and void of any usable fuel. Before the first flight of the day, the airplane was refueled, and the total usable fuel was about 32.5 gallons. The airplane recording tachometer indicated that 2.2 tachometer hours had been accumulated since that time. Although the airplane operator reported that, according to historical fueling and flight data, the airplane's average fuel consumption rate was about 10.2 gallons per tachometer hour, the calculated average fuel consumption rate was 14.8 gallons per tachometer hour since the last refueling. Although the total loss of engine power was caused by fuel exhaustion, the investigation could not determine the reason for the above-normal fuel consumption rate. However, if the pilot had determined the actual fuel consumption rate between flights, he should have identified that insufficient fuel was available to complete the accident flight.

Text from the NTSB. Open the NTSB docket for CEN14LA261 for the full record.