NTSB Identification: LAX06FA075.
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Accident occurred Saturday, December 31, 2005 in Valley Center, CA
Probable Cause Approval Date: 08/30/2007
Aircraft: Beech V35A, registration: N7944R
Injuries: 3 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The airplane collided with terrain following a loss of control during the takeoff/initial climb. This airplane was the last of five airplanes that were traveling to another airport for the group's overnight trip. Witnesses heard a loud bang as the airplane reached about 800 feet above ground level (agl). They observed the airplane roll once or twice as the nose went down. The airplane came to rest with the tail in an avocado tree and was largely consumed by fire. Investigators could not establish control continuity due to the extensive mechanical and thermal damage. Investigators disassembled the fuel manifold valve. The screen, interior, and the line going to the pressure gauge had a thin coating of a viscous amber substance that had a strong, foul odor. The most likely source of the residue appeared to be biological contamination of the fuel, based on the major peaks in the gas chromatography with a mass spectrometer detector (GC/MS) spectra for the fatty acids and fatty nitriles having even numbers of carbon atoms. None of the additives or sealants approved by Teledyne Continental Motors appeared in the GC/MS identification, and it did not appear that the compounds identified in the spectra could be simple breakdown or combustion products of the approved additives or sealants. The substance did not clog the valve or screen. The fuel nozzles were open. Investigators found no anomalies that would have prevented normal operation or production of rated power.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

the pilot's failure to maintain an adequate airspeed margin following a loss of engine power in the takeoff initial climb, resulting in a stall/spin. While the laboratory tests indicated the presence of an unknown biological contaminant in the fuel manifold valve, the amount of contamination could not be established and thus the underlying reason for the loss of engine power was not determined.

Full narrative available

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