Incident Overview
A flight instructor (CFI) was conducting a Biennial Flight Review (BFR) for the owner of a tailwheel-equipped airplane. The owner’s BFR was not current, and the airplane’s last annual inspection had lapsed. Before the flight, the owner filled the airplane’s fuel tanks from a personal fuel tank that contained a mixture of 25 percent aviation fuel and 75 percent automotive fuel.
Flight and Engine Failure
The owner reported draining the airplane’s fuel tanks before the flight and did not notice any contamination. An engine run-up was completed with no deficiencies, and the fuel selector was positioned to the left tank. After takeoff, when the airplane reached about 400 feet above ground level, the engine began to lose power and run roughly.
Emergency Landing
The owner selected an emergency landing area in a location with small trees and brush. The airplane collided with several trees, resulting in damage to the fuselage and wings.
Postaccident Examination
A postaccident examination of the airplane revealed water in the carburetor and the left wing fuel tank. An analysis of fuel from the owner’s storage tank failed the specifications for aviation gasoline.