there are some distinct differences between avgas and auto
fuel. Not only are the specifications on the quality of avgas
more stringent, but avgas is more stable over time, and less
prone to the production of gum- and varnish-like deposits
that can plague fuel systems. Is there a lesson here? As the
pilot in the Luscombe accident recommends using fresh
fuel and, “Completely drain old fuel from the tank at the
end of the flying season.”
Without a doubt, a little bit of preventive maintenance
can go a long way in preventing fuel-contamination
accidents, as the pilot of a Bellanca 14-13-2 learned after a
short yet harrowing flight in Ellijay, Georgia. The pilot had
flown over his home and was headed back to the airport
at 3,200 feet mean sea level when the engine lost power.
He managed to get it restarted several times, but each time
it ran just briefly before quitting again. He chose a field in
which to make a forced landing but was unable to clear a
tree line. He crashed into the trees and came to rest inverted
in a private driveway.
The investigation found a number of discrepancies. First,
the aircraft was equipped with a number of automotive
(read that “non-approved”) components, including the
starter relay, battery, and fuel boost pump. While the
pilot had been using auto fuel, there was no evidence
that the aircraft was approved for such. According to the
NTSB report, “Examination of the fuel system including
disassembly of the carburetor, gascolator, and boost pump
found contamination of both the gascolator and boost
Crossword Puzzle Solution
(from page 65)
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pump. The contamination consisted of insect parts and
a sandy substance similar to dirt. The sandy substance
was observed caked and blocking the stand pipe in the
fuel gascolator, which would have prevented fuel from
reaching the carburetor resulting in a loss of engine
power.” Surprisingly, the aircraft had undergone an annual
inspection the month prior to the accident, and the aircraft
had only been flown 4. 4 hours since that time. Perhaps the
inspection wasn’t quite as thorough as it could have been.
Ice Contaminates, Too
Pilots should also remember that when temperatures drop
below freezing, fuel contamination can take the form of
ice crystals that block fuel filters and restrict fuel flow. Such
was the case for the 23,000-hour, airline transport pilot of
a Cessna 150 who departed Port Elsner Airport (75WA), a
private grass airstrip in White Salmon, Washington, on a
sunny, yet chilly February morning. A witness who was
hiking in the area watched the bright yellow aircraft take
off. Seconds later, the engine noise stopped, and she turned
to see the aircraft stall and crash. The wreckage was located
about 500 feet west of the end of Runway 17, and the pilot
was seriously injured in the crash.
Apparently the aircraft had been parked outside, and
heavy rains had occurred over the past several days. The
investigation revealed that there was water mixed with
the fuel in the carburetor, and “approximately one to two
tablespoons of frozen water were found in the fuel strainer.”
