Imbalanced fuel flow: was Re: REFLECTOR:Low fuel light
Simon Aegerter
reflector@tvbf.org
Thu, 24 Jul 2003 17:25:55 +0200
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>I am still wondering if the left tank goes to 0
Chuck:
you land on an Interstate on ramp. Has been done before! The
following is from the NTSB:
-----------
On June 15, 1999, about 1004 eastern daylight time, a White Velocity
XL/RG, N19DW, registered to a private individual, operating as a
Title 14 Part 91 personal flight, crashed landed on an interstate
highway following a loss of engine power while attempting a forced
landing at the St. Lucie County International Airport, Fort Pierce,
Florida. Visual meteorological conditions prevailed and no flight
plan was filed. The aircraft sustained substantial damage and the
private-rated pilot, the sole occupant, was not injured. The flight
originated from Hollywood, Florida, about 34 minutes before the
accident.
Full narrative:
On June 15, 1999, about 1004 eastern daylight time, a White Velocity
XL/RG, N19DW, registered to a private individual, operating as a
Title 14 Part 91 personal flight, crashed landed on an interstate
highway following a loss of engine power while attempting a forced
landing at the St. Lucie County International Airport, Fort Pierce,
Florida. Visual meteorological conditions prevailed and no flight
plan was filed. The aircraft sustained substantial damage and the
private-rated pilot, the sole occupant, was not injured. The flight
originated from Hollywood, Florida, about 34 minutes before the
accident.
According to the pilot/builder, he was in cruise flight at 1,500 feet
msl, about 10 miles southwest of the St. Lucie County Airport. He was
maneuvering to attain a visual on his destination, a private
airstrip. Without warning, he experienced a rapid decrease of engine
power that activation of the electric fuel boost pump appeared to
remedy. One or 2 minutes later, the engine again lost power and he
noticed the fuel pressure gage indicating zero. He turned toward St.
Lucie County Airport, but when it became obvious to him that engine
power available would not sustain flight to the airport, he chose the
highway for a forced landing. The aircraft collided with pole-mounted
power transmission lines on approach to the highway about 4 miles
west of the St. Lucie County Airport, that caused a hard touchdown to
the pavement. He estimated that his fuel distribution at the
beginning of the flight to be 5 to 10 gallons in the right tank, 10
to 12 gallons in the left tank, and 3 gallons in the sump tank. He
further stated that he had recently replaced the factory-provided
wing tank fuel caps with a different set of caps about a week before
the accident. The new caps were not vented, and in retrospect, he
stated the caps did not feel as tightly sealed to the filler pipe
flange as the previous ones, but thought no more of it. He added that
he began to have fuel balance problems that he had not experienced
before, but did not make the connection.
According to St. Lucie County FAA Control Tower personnel, at 1002
the pilot radioed that he was a possible emergency due to low fuel
pressure and shortly thereafter, advised that he could not make the
field due to low power and was landing on I-95.
Subsequent examination of the wreckage and interview of the
pilot/builder by FAA personnel revealed that the aircraft is
configured with a 33-gallon fuel tank in each wing that gravity feeds
into a fuselage mounted 3-gallon sump tank and thence to the
aft-mounted engine via an electric driven boost pump. There is no
fuel selector valve on the aircraft. The fuel quantity indication
system consisted of graduations on a left and right sight-gage made
of clear flex-tubing spliced inline with fuel feed lines between the
wing tanks and the sump tank and routed into the cabin. Eight to nine
gallons of uncontaminated 100LL aviation fuel was contained in the
left wing/sump tank combination and no fuel was found in the right
tank, postcrash. The wreckage was subsequently moved to county
property where operational testing of the fuel system and engine was
conducted. The engine started with no problems and exhaust sound was
relatively smooth and consistent. High end rpm was not tested due to
propeller damage and imbalance.
The new fuel tank caps are shipped from the kit factory with
adjustment instructions attached, but the pilot does not remember
seeing them, (a copy of the instructions is included in this report).
All three tanks are vented to the outside atmosphere, but inspection
of the total vent system revealed some plumbing component's inside
diameter measurements to be as small as .18 inch. Pressurizing either
wing tank with air revealed that the fuel vent system could not
adequately equalize the pressure, and air bypass at the loosest
fitting fuel cap occurred. It is reasoned that the opposite would
also take effect, i.e. a negative pressure as occurs above the wing
during flight would also cause air bypass, (siphoning of air) out of
the wing tank through the loose fitting cap. The net effect would be
a low pressure or vacuum created in the wing fuel tank that would
interfere with gravity feed into the sump tank and eventual fuel
starvation. The factory provides, as an option to the basic airplane
kit at additional cost, a "low fuel" warning light for the sump tank,
but this airplane was not so equipped.
As a result of this occurrence, flight testing was performed at the
Velocity Aircraft Factory, Sebastian, Florida, using loose-fitting
fuel tank caps in an attempt to duplicate the conditions present
during the accident. It was revealed that the wing tanks did, in
fact, stop their gravity feed and the sump tank quantity started
decreasing when using the loose cap. As a result of the testing, the
factory is experimenting with replacing the 1/4 inch fuel vent tubing
with 3/8 inch tubing in the wing tanks. Additionally, the factory
eliminated the sump fuel vent in favor of an air bleed-off valve or
"burp" valve for use during pilot's preflight walk-around inspection.
The factory has also issued an alert via newsletter to all kit owners
concerning the hazards of using loose-fitting wing tank fuel caps.
Applicable excerpts from that newsletter are included in this report.
-----------------
That should answer a couple of questions...
Best
Simon
--
Simon Aegerter, Wollerau, Switzerland
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--></style><title>RE: Imbalanced fuel flow: was Re: REFLECTOR:Low
fuel l</title></head><body>
<blockquote type="cite" cite>I am still wondering if the left tank
goes to 0</blockquote>
<div><br></div>
<div>Chuck:</div>
<div><br></div>
<div>you land on an Interstate on ramp. Has been done before! The
following is from the NTSB:</div>
<div><br></div>
<div>-----------</div>
<div><font face="Times" size="+2" color="#000000">On June 15, 1999,
about 1004 eastern daylight time, a White Velocity XL/RG, N19DW,
registered to a private individual, operating as a Title 14 Part 91
personal flight, crashed landed on an interstate highway following a
loss of engine power while attempting a forced landing at the St.
Lucie County International Airport, Fort Pierce, Florida. Visual
meteorological conditions prevailed and no flight plan was filed. The
aircraft sustained substantial damage and the private-rated pilot, the
sole occupant, was not injured. The flight originated from Hollywood,
Florida, about 34 minutes before the accident.</font><br>
<font face="Times" size="+2" color="#000000"></font></div>
<div><font face="Times" size="+2" color="#0000FF">Full
narrative:</font></div>
<div><font face="Times" size="+2" color="#000000"><br>
On June 15, 1999, about 1004 eastern daylight time, a White Velocity
XL/RG, N19DW, registered to a private individual, operating as a Title
14 Part 91 personal flight, crashed landed on an interstate highway
following a loss of engine power while attempting a forced landing at
the St. Lucie County International Airport, Fort Pierce, Florida.
Visual meteorological conditions prevailed and no flight plan was
filed. The aircraft sustained substantial damage and the private-rated
pilot, the sole occupant, was not injured. The flight originated from
Hollywood, Florida, about 34 minutes before the accident.<br>
According to the pilot/builder, he was in cruise flight at 1,500 feet
msl, about 10 miles southwest of the St. Lucie County Airport. He was
maneuvering to attain a visual on his destination, a private airstrip.
Without warning, he experienced a rapid decrease of engine power that
activation of the electric fuel boost pump appeared to remedy. One or
2 minutes later, the engine again lost power and he noticed the fuel
pressure gage indicating zero. He turned toward St. Lucie County
Airport, but when it became obvious to him that engine power available
would not sustain flight to the airport, he chose the highway for a
forced landing. The aircraft collided with pole-mounted power
transmission lines on approach to the highway about 4 miles west of
the St. Lucie County Airport, that caused a hard touchdown to the
pavement. He estimated that his fuel distribution at the beginning of
the flight to be 5 to 10 gallons in the right tank, 10 to 12 gallons
in the left tank, and 3 gallons in the sump tank. He further stated
that he had recently replaced the factory-provided wing tank fuel caps
with a different set of caps about a week before the accident. The new
caps were not vented, and in retrospect, he stated the caps did not
feel as tightly sealed to the filler pipe flange as the previous ones,
but thought no more of it. He added that he began to have fuel balance
problems that he had not experienced before, but did not make the
connection.<br>
According to St. Lucie County FAA Control Tower personnel, at 1002 the
pilot radioed that he was a possible emergency due to low fuel
pressure and shortly thereafter, advised that he could not make the
field due to low power and was landing on I-95.<br>
Subsequent examination of the wreckage and interview of the
pilot/builder by FAA personnel revealed that the aircraft is
configured with a 33-gallon fuel tank in each wing that gravity feeds
into a fuselage mounted 3-gallon sump tank and thence to the
aft-mounted engine via an electric driven boost pump. There is no fuel
selector valve on the aircraft. The fuel quantity indication system
consisted of graduations on a left and right sight-gage made of clear
flex-tubing spliced inline with fuel feed lines between the wing tanks
and the sump tank and routed into the cabin. Eight to nine gallons of
uncontaminated 100LL aviation fuel was contained in the left wing/sump
tank combination and no fuel was found in the right tank, postcrash.
The wreckage was subsequently moved to county property where
operational testing of the fuel system and engine was conducted. The
engine started with no problems and exhaust sound was relatively
smooth and consistent. High end rpm was not tested due to propeller
damage and imbalance.</font></div>
<div><font face="Times" size="+2" color="#000000">The new fuel tank
caps are shipped from the kit factory with adjustment instructions
attached, but the pilot does not remember seeing them, (a copy of the
instructions is included in this report). All three tanks are vented
to the outside atmosphere, but inspection of the total vent system
revealed some plumbing component's inside diameter measurements to be
as small as .18 inch. Pressurizing either wing tank with air revealed
that the fuel vent system could not adequately equalize the pressure,
and air bypass at the loosest fitting fuel cap occurred. It is
reasoned that the opposite would also take effect, i.e. a negative
pressure as occurs above the wing during flight would also cause air
bypass, (siphoning of air) out of the wing tank through the loose
fitting cap. The net effect would be a low pressure or vacuum created
in the wing fuel tank that would interfere with gravity feed into the
sump tank and eventual fuel starvation. The factory provides, as an
option to the basic airplane kit at additional cost, a "low fuel"
warning light for the sump tank, but this airplane was not so
equipped.<br>
As a result of this occurrence, flight testing was performed at the
Velocity Aircraft Factory, Sebastian, Florida, using loose-fitting
fuel tank caps in an attempt to duplicate the conditions present
during the accident. It was revealed that the wing tanks did, in fact,
stop their gravity feed and the sump tank quantity started decreasing
when using the loose cap. As a result of the testing, the factory is
experimenting with replacing the 1/4 inch fuel vent tubing with 3/8
inch tubing in the wing tanks. Additionally, the factory eliminated
the sump fuel vent in favor of an air bleed-off valve or "burp"
valve for use during pilot's preflight walk-around inspection. The
factory has also issued an alert via newsletter to all kit owners
concerning the hazards of using loose-fitting wing tank fuel caps.
Applicable excerpts from that newsletter are included in this
report.</font></div>
<div>-----------------</div>
<div><br></div>
<div>That should answer a couple of questions...</div>
<div><br></div>
<div>Best</div>
<div>Simon</div>
<x-sigsep><pre>--
</pre></x-sigsep>
<div>Simon Aegerter, Wollerau, Switzerland</div>
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