Aviation Accident Summaries

Aviation Accident Summary CHI98LA352

IRISH HILLS, MI, USA

Aircraft #1

N447FC

Fieseler Flugzeugbau F-156C-1

Analysis

The World War II vintage airplane's engine experienced a total loss of power shortly after takeoff. During the forced landing, the airplane collided with electrical power lines and the ground. The pilot said the airplane's engine had been experiencing vapor lock problems in the past and that the engine had quit in the same manner as before. The airplane's fuel tank had leaked about 25-gallons of fuel on the ground after the accident had occurred. According to the pilot, the airplane's side cowling assemblies were taken off when the outside air temperature (OAT) exceeded 45-degrees Fahrenheit. This was supposed to eliminate the vapor lock potential. The OAT on the day of the accident was 80- degrees Fahrenheit. The airplane's side cowling had been removed before the accident flight. No other mechanical anomalies were found that would identify why the engine experienced a total loss of power.

Factual Information

On September 20, 1998, at 1015 eastern standard time, a Fiesler F-156C-1 Storch, N447FC, piloted by a private pilot, was substantially damaged during a collision with electrical power lines and the ground while maneuvering during a forced landing approach. The pilot reported the engine experienced a total loss of power during the airplane's initial climb out from takeoff. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 personal flight was not operating on a flight plan. The pilot and passenger reported no injuries. The flight departed from a restricted landing area near Onsted, Michigan, exact time unknown. According to the pilot's written statement, "Past the end of the runway and above the trees, the engine lost power... ." He said he was unable to identify any engine sound changes because of the headphones he was wearing. The pilot's wife said the airplane began climbing above the trees "...but then we did not continue to climb... " The on-scene investigation revealed about 35 gallons of fuel was in the fuel tanks. According to the Lenawee County Michigan, Sheriff's Office, about 25 gallons leaked from the right wing's fuel tank. According to the Federal Aviation Administration Principal Maintenance Inspector (PMI), the pilot stated the airplane's engine had been experiencing vapor lock problems before the accident flight. The pilot said this was a design problem that is usually corrected by removing the side cowling from the airplane's 4-piece cowl structure. The pilot said the airplane was operated in this manner during World War II. He provided photographs showing the airplane with and without the side cowling installed. According to the PMI, the pilot said the vapor lock problem had caused the engine to quit in the past. The vapor lock problems occur when the outside air temperature (OAT)is above 45-degrees fahrenheit, according to the pilot. The side cowls were removed from the airplane before the accident flight. The PMI said the OAT was 80-degrees at the time of the accident. No mechanical anomalies were found that would identify why the airplane experienced a total loss of engine power.

Probable Cause and Findings

the pilot selected to operate the airplane with a known deficiency. A factor in this accident was the vapor lock experienced by the engine's carburetor.

 

Source: NTSB Aviation Accident Database

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