Incident Overview
During cruise flight at approximately 2,000 feet above ground level, the pilot observed fluctuations in fuel flow, which were followed by a complete loss of engine power. In response, the pilot switched fuel tanks and set the mixture control to the FULL RICH position. He also kept the electric fuel pump activated and alternated the fuel boost pump switch between the HIGH and LOW positions. The engine would intermittently run for a few seconds before losing power again.
Forced Landing
Determining that the airplane could not reach the airport, the pilot executed a forced landing on an off-airport gravel bar.
Postaccident Inspection
A postaccident inspection revealed that the right fuel tank was empty, while the left fuel tank contained approximately 25 gallons of fuel. The engine was subsequently started and operated normally during testing.
Relevant Manual Information
The Cessna U206 pilot operating manual includes specific instructions for in-flight engine restart after running a fuel tank dry. It advises that upon the first indication of fuel pressure fluctuation or power loss, the pilot should immediately switch to a tank containing fuel. Then, the right half of the auxiliary fuel pump switch should be placed in the ON position momentarily (3 to 5 seconds) with the throttle at least half open. The manual warns that excessive use of the ON position at high altitude and full rich mixture can cause engine flooding, characterized by a short (1 to 2 seconds) period of power followed by a loss of power, which may be detected by a fuel flow indication with lack of power. If flooding occurs, the auxiliary fuel pump switch should be turned off, and normal propeller windmilling should restart the engine within 1 to 2 seconds.