Cessna U206E N9129M accident near Anchorage, Alaska

Probable cause

The pilot’s decision to depart with minimal fuel and his improper fuel management and engine restart procedures, which resulted in a loss of engine power due to fuel starvation. Contributing to the accident was the Pilot Operating Handbook did not provide the altitude or time that would be lost in the event of an engine restart.

NTSB analysis

The pilot was returning from a remote lodge when the airplane’s engine lost power, resulting in an off airport emergency landing. During the landing, the airplane nosed over. The pilot reported that prior to departure from the lodge, there were 26 gallons of fuel in the right main fuel tank, and 8 to 10 gallons in the left main fuel tank. He commonly used the fuel in the right tank for the flight, and the left tank fuel was the reserve supply. When the engine lost power, he switched fuel tanks, and held the emergency fuel boost pump on for about 3 seconds. When the engine did not respond, he moved the fuel lever back and forth, turned the boost pump on, and moved the fuel mixture control to the full rich position. Unable to restart the engine, he made an off airport emergency landing.

The right front seat passenger said that prior to takeoff, he asked the pilot if they had enough fuel, because all four fuel gauges were on or near the empty mark. An examination of the airplane revealed that the right main fuel tank was empty, and about 3 inches of fuel remained in the left main fuel tank. The left header tank was full, and the right header tank contained a small quantity of fuel and water. No mechanical anomalies were found with the fuel system. The engine was test run and it operated satisfactorily.

According to the airplane’s Pilot Operating Handbook (POH), the minimum fuel for the flight (without the required VFR reserve) would have been about 26.8 gallons. The POH treats the running of a fuel tank below a usable level in-flight as a normal operating procedure, but has very specific guidelines for engine restart. The pilot did not follow those procedures. The POH does not discuss the altitude lost or time required for a successful engine restart.

Considering the witnesses’ observations, the postaccident examination of the fuel system and the successful engine operation, it is likely that the pilot inadvertently ran the right main fuel tank below a usable level. Due to the low altitude, time available, and his incorrect restart procedure, he was unable to get the engine restarted to avoid an off-airport landing.

Eighty-nine fuel related accidents involving Cessna single-engine airplanes were reviewed, disclosing that 52 of those accidents were initiated by a fuel tank either being intentionally or unintentionally run below a usable level. All 89 accidents resulted from the pilot not being able to get the engine restarted. Of the major airplane manufacturers producing piston engine powered airframes, Cessna is the only one that places a loss of engine power due to intentionally running a fuel tank below a usable level in the “Normal” operating section of its POH.

Text from the NTSB. Open the NTSB docket for ANC11LA061 for the full record.