Pilot miscalculates fuel

This September 2010 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.

Aircraft: Cessna 172. Injuries: 2 Fatal, 1 Serious. Location: Chatsworth, Ga. Aircraft damage: Destroyed.

What reportedly happened: A private pilot and CFII filed an IFR flight plan. The pilot calculated a fuel burn rate of nine gallons per hour. Approximately two hours and 30 minutes after departure, the pilot canceled his IFR flight plan with the ATC without giving a reason and changed his destination airport. One minute later, he reported engine failure.

Witnesses in the vicinity of the crash site said the airplane’s engine was not running as it flew overhead at tree-top level before making a steep right turn and crashing into trees.

No mechanical malfunctions were found. Both fuel tanks were intact. The right tank contained one quart of fuel. The left tank had 2.5 gallons of fuel, two of which were considered unusable fuel.

Review of the airplane logbooks revealed the engine had been increased to 160 horsepower, which resulted in an increase in airplane’s fuel burn rate. The modification had been done eight years before the accident by Supplemental Type Certificate. A copy of the STC was not located in the airplane wreckage.

The registered owner reported the pilot had received instruction on the STC, however, no documentation was provided substantiating this instruction. The owner further stated the STC only increased the fuel burn rate for the first five minutes of flight at takeoff power. Review of the engine Operator’s Manual revealed the maximum fuel usage at full power is about 13.6 gallons per hour. At 82% power, the fuel burn rate is about 11.25 gallons per hour.

Probable cause: The pilot’s inadequate flight planning and in-flight fuel management, resulting in a total loss of engine power due to fuel exhaustion. Contributing to the accident was the operator’s failure to ensure aircraft records pertaining to engine modifications and fuel burn rates were available to flight crew members.

For more information: NTSB.gov. NTSB Identification: ERA10FA502

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