ANC21LA033 · Cessna 140

The pilot reported that, after lining up on the final approach to landing and nearing the runway, he was unhappy with the approach, and elected to conduct a go-around. He applied full power, pushed in the carburetor heat, accelerated to 60 knots airspeed, and initiated a climb. When the airplane was about 100 ft above the treetops on the south end of the airport, the engine lost all power. He attempted to restart the engine but was not successful. The airplane touched down in an area of muskeg and bounced several times before it nosed over, sustaining substantial damage to the left lift strut.

The airplane Flight Manual, Power Plant Instrument, stated in part:

Fuel Quantity Gauge – Do not takeoff on a fuel tank less than ¼ full.

Examination of the wreckage by a mechanic found no anomalies to explain the loss of engine power and found the fuel selector placed to the right tank position. Although the right fuel gauge indicated less than 1/4 fuel, and the aircraft flight manual warned not to takeoff on a fuel tank less than 1/4 full, the fuel onboard at the time of the accident could not be determined due to the disposition of the wreckage. The airplane was equipped with 2 -12.5-gallon fuel tanks with left, right, or off, fuel selector positions.

According to a representative from the aircraft manufacturer, the fuel quantity limitation for takeoff was due to the location of the fuel pickup tubes in the fuel tanks. Fuel unporting was possible at takeoff and climb attitudes when the fuel was less than ¼ full. No markings were present on the fuel gauges to indicate a takeoff limitation when the fuel tank was less than ¼ full, which would be about 3.125 gal per fuel tank.

According to the operation manual for the airplane, a cruise power setting between sea level and 10,000 mean seal level would yield a fuel burn of about 4.2 gallons per hour. The pilot indicated that the 1.9-hour flight departed with 15 gallons of fuel and he performed numerous maneuvers during the flight. Flight track data showed the airplane’s altitude varied between 7,400 ft and 100 ft. A 4.2 gph fuel burn over a span of 1.9 hours equates to about 8 gallons of fuel burned, which would have left about 3.5 gal of fuel in each of the two wing fuel tanks if the fuel was used evenly between the two tanks.

Although a postaccident examination found some contaminates within the fuel system, the amount and size were not enough to cause a total loss of engine power. The temperature and dewpoint at the time of the accident placed the airplane on the edge of the regime for carburetor icing at glide power; however, carburetor icing is unlikely to have been an issue since the pilot applied carburetor heat during the approach to land. It is therefore likely that insufficient fuel remained for takeoff which resulted in unporting of the fuel pickups and a total loss of engine power.

Verbatim NTSB analysis and probable cause from the NTSB dataset