TALKEETNA, AK, USA
N126KT
Cessna TU206
In cruise flight, about 2,000 feet above ground level, the pilot noticed fuel flow fluctuations, followed by a total loss of engine power. He switched fuel tanks, and placed the mixture control to the FULL RICH position. The pilot kept the electric fuel pump activated, alternately placing the fuel boost pump switch in the HIGH position, and then the LOW position. The pilot described the engine as alternately running for a few seconds, then losing power. He determined the airplane would not reach the airport, so he performed a forced landing on an off airport gravel bar. Postaccident inspection revealed the right fuel tank was empty, and the left fuel tank contained about 25 gallons of fuel. The engine was started and operated normally. The Cessna U206 pilot operating manual states: 'To ensure a prompt engine restart in-flight after running a fuel tank dry, immediately switch to the tank containing fuel at the first indication of fuel pressure fluctuation and/or power loss. Then place the right half of the auxiliary fuel pump switch in the ON position momentarily (3 to 5 seconds) with the throttle at least 1/2 open. Excessive use of the ON position at high altitude and full rich mixture can cause flooding of the engine as indicated by a short (1 to 2 seconds) period of power followed by a loss of power. This can be detected by a fuel flow indication accompanied by a lack of power. If flooding does occur, turn off the auxiliary fuel pump switch, and normal propeller windmilling should start the engine in 1 to 2 seconds.'
On June 29, 1999, about 1630 Alaska daylight time, a Cessna TU206 airplane, N126KT, sustained substantial damage during a forced landing about four miles northwest of the Talkeetna Airport, Talkeetna, Alaska. The commercial pilot and the four passengers aboard were not injured. The airplane was being operated by K2 Adventures, Inc., of Talkeetna, under 14 CFR Part 135, as a local air tour flight. The flight departed Talkeetna at 1505. Visual meteorological conditions prevailed at the time of the accident, and a company VFR flight plan was filed. The pilot told the NTSB investigator-in-charge (IIC) during a telephone interview on June 29, that the flight was about 14 miles northwest of the airport, in cruise flight at 2,000 feet above ground level. The pilot said he noticed fuel flow fluctuations, followed by a total loss of engine power. He stated that he switched the fuel selector valve handle to the left fuel tank position, and turned on the electric fuel boost pump. He said that he kept the electric fuel pump activated, alternately placing the fuel boost pump in the HIGH position, then the LOW position. The pilot indicated that he kept the mixture control in the FULL RICH position, and did not turn the electric boost pump switch to the OFF position. He described the engine as alternately running for a few seconds, and then losing power. The pilot determined he would not reach the airport, and selected an off airport gravel bar for a forced landing. The airplane touched down on the gravel, and came to rest on the river bank, damaging the underside of the fuselage. The airplane was airlifted to the Talkeetna Airport on June 30, where it was inspected by a company mechanic and an FAA airworthiness inspector. The fuel selector valve handle was found selected to the left fuel tank position. The right fuel tank was empty, and the left fuel tank contained about 25 gallons of fuel. The engine was started and operated normally. The fuel boost pump operated in both the HIGH and LOW position. The fuel system was pressurized by the electric fuel boost pump with the engine not operating, and no fuel leaks were observed. The Cessna U206G Pilot Operating Handbook, section 7, page 7-26, contains the following statement: "To ensure a prompt engine restart in-flight after running a fuel tank dry, immediately switch to the tank containing fuel at the first indication of fuel pressure fluctuation and/or power loss. Then place the right half of the auxiliary fuel pump switch in the ON position momentarily (3 to 5 seconds) with the throttle at least 1/2 open. Excessive use of the ON position at high altitude and full rich mixture can cause flooding of the engine as indicated by a short (1 to 2 seconds) period of power followed by a loss of power. This can be detected by a fuel flow indication accompanied by a lack of power. If flooding does occur, turn off the auxiliary fuel pump switch, and normal propeller windmilling should start the engine in 1 to 2 seconds."
The pilot not following emergency procedures, and improper use of the electric fuel boost pump, while attempting to restart the engine in flight. A factor associated with this accident was the inadequate fuel consumption calculations by the pilot.
Source: NTSB Aviation Accident Database
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