Cessna C175A N6868E accident near Groveland, California

Probable cause

A total loss of engine power due to fuel starvation as a result of a blocked fuel line that was improperly fabricated by the pilot. Also causal was the pilot's excessive ground speed during the taxi tests that resulted in an inadvertent takeoff.

NTSB analysis

The pilot, who was also a certificated airframe and powerplant mechanic, was conducting a series of high-speed taxi tests after installing a recently purchased engine. While performing the tests, the airplane's ground speed became excessive and it encountered a gust of wind. The airplane unintentionally became airborne and continued to climb. The pilot attempted to return back to the airport but the engine experienced a total loss of power. The airplane subsequently collided with a telephone pole and descended nose-low onto the road below. A Federal Aviation Administration inspector performed a postaccident examination of the airframe and engine. During the disassembly of the fuel line connecting the gascolator to the carburetor, he observed a condition inside the line known as a "flapper valve" at both end fittings. The inspector stated that this was the fuel line that the pilot had recently fabricated. He stated that the "flapper valve" condition can occur as a result of the end fittings being installed without using a mandrel, where the fitting edge cuts the inside of the hose creating a valve-like piece that obstructs fuel flow.

Text from the NTSB. Open the NTSB docket for LAX08LA118 for the full record.