Pilot Debrief

CESSNA 152 near Eugene, OR — 2012-09-29

Final reportWPR12LA439
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Date
2012-09-29
Location
Eugene, OR, USA
Aircraft
CESSNA 152
Registration
N95840
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Cruise

Probable cause

A total loss of engine power due to fuel exhaustion during cruise flight for reasons that could not be determined because postaccident examination did not reveal any anomalies that would have resulted in the loss of engine power.

NTSB narrative

The flight instructor and the student pilot were part of a community college flight technology department, and the airplane was owned and maintained by the department. The flight instructor reported that, when he conducted the airplane's first flight of the day, he took off with the fuel tanks completely full. The airplane was then used for another flight; the airplane was operated for a total of 2.5 hours after the most recent refueling. Based on both that time and his visual inspection of the fuel tanks, the instructor determined that there was sufficient fuel for 2 more hours of flight, and he and the student pilot then departed in the airplane for some basic airwork. About 42 minutes into the flight, while returning to the airport for landing, the engine experienced a power loss, and the instructor conducted a forced landing in a field about 8 miles from the airport. Examination of the airplane revealed that the total quantity of fuel remaining onboard was about 1.5 gallons, which was the same as the manufacturer's designated amount of unusable fuel. A small quantity of fuel was observed in the lower cowl, but this appeared to be consistent with spillage from the carburetor as a result of the accident. No other evidence of any in-flight or postimpact fuel leaks was observed. Postaccident engine examination did not reveal any anomalies that would have contributed to the power loss. Review of the airplane's calculated average fuel consumption rates for several recent flights revealed that the rates were consistent with the manufacturer's published data. However, the calculated fuel consumption rate during the flights since the last refueling was significantly higher than other recent flights and the manufacturer's data. Despite the industry-accepted unreliability of fuel quantity indication observations, the instructor's observation of slightly less than half full tanks before the accident flight confirmed his calculations and would have resulted in 2 hours of flying time. These calculations and the instructor's observation support the validity of his preflight planning, decisions, and actions. Although uncertainties regarding initial fuel quantity, on-site spillage, and postaccident recovered fuel quantity reduced the fidelity of that calculated value, slightly more than half of the usable fuel would have to be unaccounted for, which seems unlikely. The available evidence was insufficient to enable a determination for the reason(s) for the fuel exhaustion and subsequent engine power loss.

Analysis

Primary failure mode
Fuel management
First missed decision gate
Visual check of fuel quantity before departure could have prevented the accident.

NTSB coding

Evidence available

  • 18 docket documents
View NTSB final reportView NTSB docket

Docket documents18

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