Stupid question: water in fuel

Yes, this is a stupid question, and somewhat off topic for IFR.

But I get better answers here than elsewhere.

Question:

Why is it that devices to separate water from fuel are quite
common cars (my F-350 truck has one), but such a device, which
could save lives in an airplane, is not offered for airplanes ?
Even as a retrofit ?

Why is it that devices to separate water from fuel are quite
common cars (my F-350 truck has one), but such a device, which
could save lives in an airplane, is not offered for airplanes ?
Even as a retrofit ?

To this and other similar questions, the general answer is weight, cost,
and reliability.

Weight - all the gadgets and gizmos weigh something, and this gets
removed from your useful load. If all the safety features people wanted
were included, the airplane would never fly. I guess that would be
pretty safe. Cars don't have to fly, so they can be as heavy as it
takes - a few pounds here and there don't really make a difference. But
in the air they do.

Cost - mainly certification cost, since any newfangled gizmo has to go
through the FAA wringer to ensure that there are no unexpected
surprises. Whether this is actually effective or not is subject to
debate (witness the homebuilt arena) but it is necessary.

Reliability - it's another gizmo to go TU, with unpleasant side effects.
Cars can pull over when they break. Planes can't. In the case of
this particular item (fuel/water separators), it would still not relieve
the pilot of the necessity to check for water in the gas, since we all
know that things that "shouldn't" happen, do anyway.

Jose
--
Money: what you need when you run out of brains.
for Email, make the obvious change in the address.

You can use a GATS jar for checking your fuel. It has a screen that
removes water when you pour back into the tank.

My guess is that water separator are rather new, and the volume doesn't
justify anyone producing a certified unit for aircraft?

On Fri, 14 Oct 2005 13:28:51 -0700, Scott Moore
wrote:

Yes, this is a stupid question, and somewhat off topic for IFR.

But I get better answers here than elsewhere.

Question:

Why is it that devices to separate water from fuel are quite
common cars (my F-350 truck has one), but such a device, which
could save lives in an airplane, is not offered for airplanes ?
Even as a retrofit ?

I wasn't aware that there are any airplanes without water separators.

My Cherokee has quick drains on each tank and each fuel manifold to
check and drain any accumulated water. Checking for water is a
preflight item. Before the fuel enters the carburetor it goes through
a gascolator to separate dirt and water, which can also be tested with
a quick drain. And of course the last chance is the carburetor bowl
itself, which no one ever seems to check at annual, no matter how much
I insist, but there's a drain plug nevertheless.

Most other airplanes I've looked at seem similarly equipped. I believe
the thesis for this topic is flawed.

I never bother checking for water in the fuel on my car. There's no
provision for checking the car for water anyway without disassembling
stuff.

RK Henry

paul kgyy wrote:
You can use a GATS jar for checking your fuel. It has a screen that
removes water when you pour back into the tank.

My guess is that water separator are rather new, and the volume doesn't
justify anyone producing a certified unit for aircraft?


Not new at all. They've been used on diesel engines for at least 25
years. I had a water trapping filter on my fuel pump tank when I owned
a 182 and ran auto gas in it. I definitely didn't want to be adding
water to the tanks beyond what they might collect naturally, although, I
never found water in the fuel in 6 years of flying. However, I was
always expecting it given that the 67 had fuel bladders which were known
for having wrinkles that could trap large amounts of water and let it
loose at inopportune times. My partner and I always did a vigorous wing
rock before draining the sumps, however, we never found anything. We
did have the flush fuel cap upgrade which was supposed to greatly reduce
the change of water ingestion.

I'm not sure why they aren't used on airplanes, other than they add
cost, weight, and another item to get certified. Also, although I never
saw the problem on the diesels I used to operate, it may be that the
filter has a nasty failure mode if it collects enough water. For
example, maybe they clog completely. I don't know, just wondering if
there isn't some downside like that which obviates the benefit for
airplane use.

Matt

Scott Moore wrote:
Yes, this is a stupid question, and somewhat off topic for IFR.

But I get better answers here than elsewhere.

Question:

Why is it that devices to separate water from fuel are quite
common cars (my F-350 truck has one), but such a device, which
could save lives in an airplane, is not offered for airplanes ?
Even as a retrofit ?


Your F350 is a diesel. Gas engines in cars and trucks don't have water
seperators. Cars and trucks don't have a way to test the fuel like
aircraft.

My 1983 Ford F-250 diesel truck has a water seperator.

My 1983 Ford F-250 diesel truck has a water seperator.

On 10/14/2005 6:40 PM, Newps wrote:


Scott Moore wrote:
Yes, this is a stupid question, and somewhat off topic for IFR.

But I get better answers here than elsewhere.

Question:

Why is it that devices to separate water from fuel are quite
common cars (my F-350 truck has one), but such a device, which
could save lives in an airplane, is not offered for airplanes ?
Even as a retrofit ?


Your F350 is a diesel. Gas engines in cars and trucks don't have water
seperators. Cars and trucks don't have a way to test the fuel like
aircraft.


My 1993 Ford Clubwagon XLT 350 (E350) has a water separator. It's
a 5.8L V8 Gas engine.

--
Mark Hansen, PP-ASEL, Instrument Airplane
Sacramento, CA

I've never encountered water in a/c fuel either. However, I did in an
auto once and I wonder how a water separator would have handled it.

I filled up an almost empty '95 Caravan with fuel that had a great deal
of water in it. The van died before turning out of the station. After
damning my luck at a breakdown on a raining winter evening 100s of miles
from home, we looked for a meal and a hotel. Then I noticed that there
were several people milling about the interstate exit, on foot! No one
walks anywhere in January at an interstate exit. Further observation
found that a number of cars were parked irregularly all over the place.

I put 2 and 2 together and immediately went in the station and suggested
that water was in the fuel and that the pumps needed to be closed. The
confused teenager handling the desk didn't know what to do so insisted
she call the owners and I went out and hung signs closing the station.

Anyway, I concluded that the problem resulted from semi-melted ice all
over the parking lot. They were damming up the cold rain and the water
ran into the tanks during a fill or otherwise overcame whatever
protection is normally in place. Ever seen 3 guys chain smoke while
draining fuel tanks into 55 gallon drums.

How would water sparators work with an 'enormous' quantity of water in
the fuel?

Jose wrote:
Why is it that devices to separate water from fuel are quite
common cars (my F-350 truck has one), but such a device, which
could save lives in an airplane, is not offered for airplanes ?
Even as a retrofit ?


To this and other similar questions, the general answer is weight, cost,
and reliability.

Weight - all the gadgets and gizmos weigh something, and this gets
removed from your useful load. If all the safety features people wanted
were included, the airplane would never fly. I guess that would be
pretty safe. Cars don't have to fly, so they can be as heavy as it
takes - a few pounds here and there don't really make a difference. But
in the air they do.

Cost - mainly certification cost, since any newfangled gizmo has to go
through the FAA wringer to ensure that there are no unexpected
surprises. Whether this is actually effective or not is subject to
debate (witness the homebuilt arena) but it is necessary.

Reliability - it's another gizmo to go TU, with unpleasant side effects.
Cars can pull over when they break. Planes can't. In the case of
this particular item (fuel/water separators), it would still not relieve
the pilot of the necessity to check for water in the gas, since we all
know that things that "shouldn't" happen, do anyway.

Jose