Incident Overview
During an IFR training flight, a Gulfstream American AA-5B experienced a loss of engine power and collided with a tree short of the runway. The flight instructor had just switched fuel tanks when the engine began to run rough and subsequently stopped. Efforts to restart the engine were unsuccessful.
Preflight Inspection
The private pilot undergoing instrument training conducted the preflight inspection without the aid of the aircraft operator's manual. Notably, the pilot did not check the left and right wing fuel sump drains during the inspection.
Fuel Contamination Findings
Following the incident, fuel samples were taken from the right and left wing tank fuel sumps, as well as from the fuel line between the fuel pump and the carburetor. Laboratory analysis of the fuel line sample revealed it contained 12.6% water by volume. Additionally, the right fuel sump sample contained traces of water. A sample taken from the refueling truck did not show any impurities.