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Posted by "Robert Froelich" <w73rcd@earthlink.net>:
Background: I landed my TSIO550B lancair IV in a field one year ago,
walked away but the aircraft was destroyed. Since then I have been
asking how did it happen to a pilot with 44 years of flying experience,
trained at Flightcraft Inc to fly the lancair, with over 4000 hours in
piston aircraft and with 7000 hours spent building, studying, and learning
all about the aircraft. What was missing?
Reference: Product Defects that Cause Airplane Accidents by Norman Birch,
August 1992, Item e. ..Poorly Designed Engine Fuel Systems.. "Some engines
are equipped with a fuel injection system that is very sensitive to the
fuel pressure from the electric boost pump in the airplane’s fuel system.
When these low pressure fuel injection systems are subject to the output
pressure of the boost pump it causes the engine to flood and quit."
Reference: Journal of Air Law and Commerce, 18th annual Symposium, March
1-3, 1984, Dallas, Texas page 164, Section VI -- Fuel Injection, paragraph
3. "Alas, the same can not be said about the other common form of fuel
injection. It is crude in the extreme. No attempt is made to measure the
airflow to the engine. It is designed to simply pump fuel into the engine
in proportion to the mechanical position of the throttle. A simple manual
mixture control, again no more sophisticated than a faucet is used by the
pilot to keep the engine running." Page 167 "...It is apparent that
development of fuel systems ceased many years ago. Most current hardware
would have been quite familiar, if not by part number, at least by design
concept and sophistication in the 1930s. Placards and owner manual
supplements do not make good designs, they cover up existing bad ones."
The first concerns, I am aware of, about the fuel injection system occurred
in the 1960's by Cessna 210 owners, bonanza owners and the air
force flying the T-34 (air force version of the bonanza). I have talked
with pilots who remember some of the discussions along with discussions in
the American Bonanza Society publications concerning the un-metered fuel
pressure.
Reported Experiences:
1). How many times have you had a continental fuel injected engine stop on
landing roll out? It happened to me many times in bonanzas until I learned
that the engine needed more air to keep it running than it received when
the throttle was closed for landing and the rpm dropped.
2). What happens when you turn on the electric boost pump low or high
during pre-flight engine checks? At 4230 foot field elevation with the
engine at idle or just above idle, the electric fuel pump would kill my
TSIO550B engine.
3). One pilot reported to me that a friend was descending at 23,000 feet in
a lancair IV, had clouds ahead, retarded the throttle, got under the
clouds, advanced the throttle to learn that the engine was dead. He was
able to restart the engine by pulling the mixture all of the way off ...the
procedure used on the ground to start a flooded engine.
4). I accidently hit the electric fuel pump switch to high while reaching
into the back seat at 24,000 feet and the engine quit. Turning off the
pump with the propeller still turning, allowed the engine to return to a
normal air/fuel mixture and restart.
5). Lance Neibauer told me that he had an engine failure on final when he
had forgotten to turn off the low boost pump during descent. Turning it
off allowed the engine to restart.
6). A Cessna 210 was lost going into Deer Valley Airport, AZ last October
9, 2000 from engine failure on final which sounds to me like engine
flooding.
7). The following was reported here by AVIDWIZ concerning N424E:
"Inspection of the cockpit showed that the mags had been turned off and the
high boost and low boost were both in the on position." -- "The FAA
Investigator loosened the fuel line which attached to the spider valve as
well as the gascolator and found fuel in both with the spider valve fuel
still under pressure." -- an aside: The FAA inspector shortly after landing
in the field found fuel in the line to my engine's spider.
My understanding is that we have never been trained to recognize engine
flooding in flight despite that fact that it can and does occur.
Summary: I believe N424E’s engine flooded on descent. One partial solution
is to place a bendix fuel injection system on the engine. I have heard of
bonanza pilots placing bendix systems on smaller continental engines. Has
anyone placed a bendix system on a 550 engine? If so, I want to know how
it was done.
A second solution is my new rule: NEVER REDUCE THE MANIFOLD PRESSURE MORE
THAN 3 INCHES EVERY 30 SECONDS.
Bob
--- Robert Froelich
--- w73rcd@earthlink.net
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LML website: http://www.olsusa.com/mkaye/maillist.html
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Please send your photos and drawings to marvkaye@olsusa.com.
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