CHI06LA069 · Zilz Zenith CH801

The experimental amateur-built airplane contacted trees and a power pole during an off-airport forced landing following a loss of engine power. The pilot said the airplane was on its third flight since he finished building it. The purpose of the flight was to test and record engine performance at various power settings. He stated that during the flight the fuel pressure dropped below 2 pounds per square inch (psi) and the engine stopped running. He stated he was able to restart the engine, but it failed to produce power. The pilot turned toward the airport, but he did not have enough altitude to make it back, so he elected to land in a pasture with a row of trees bordering the edge of the field. The pilot stated he did not see the power lines above the trees until he was at an altitude, which was insufficient to clear the lines. He elected to fly through the tree line in order to avoid contacting the power lines. The airplane contacted a power line pole and trees prior to coming to rest in the field. Inspection of the engine and airplane failed to reveal any failure/malfunction which would have resulted in the loss of engine power. The pilot reported that he believes the loss of engine power was a result of vapor lock. He reported the gascolator is located near one of the exhaust pipes and that the loss of power occurred during a flight condition, which would have created reduced cooling through the engine cowling and increased exhaust temperatures.

Verbatim NTSB analysis and probable cause from the NTSB dataset