Water in the fuel

On Mar 15, 10:37 pm, george wrote:
In the Ag world they never park up with anything but full tanks.
And -they- still check for water.
better to never find it than it is for the engine to find it

No kidding. Not much gliding distance to futz around with switching
tanks or whatever fuel troubleshooting when your normal flying regime
is typically in or just slightly above ground effect.

On Mar 15, 2:56 am, Ron Garret wrote:
It occurred to me today that in fifteen years of flying I have never
once found water in my fuel when I've drained my tanks. Not a drop.
Ever. Am I just lucky, or is this really as rare an occurrence as it
seems to be? (I fly in SoCal. Maybe that has something to do with it.)

rg

I've only had one serious occurrence of water contamination, right
after refueling at a little airport just northwest of San Antonio. I
generally always sump my tanks after refueling, especially at strange
airports, and this time I got about a full cup of ugly brown water out
of one tank and a half cup out of the other. I complained to the FBO
and they were were rude to me for having dared to complain about their
fuel. I've never been back to that airport ever again. Three guesses
which airport that was... hint there's only one immediately due
northwest of the city.

I have seen the occasional drop or two from condensation, and also
whenever I wash my airplane (lots of water from a garden hose over the
tops of the wings) I'll get a drop or two. I've never gotten any water
from flying thru rain.

"William Hung" wrote

I've never come across any either, but my experience is limited.

How do the big boys check for water, the Boeings and the Busses?

William, the big difference here, is the fact that jet fuel, kerosene and
diesel fuel all have the ability to absorb moisture right out of the air,
and to dissolve the water in the fuel with no line of separation, like
happens with gas and water.

Right off hand, I would guess that there would be a point where it could no
longer absorb it all but I don't know for sure, right or wrong.
--
Jim in NC

On Sat, 15 Mar 2008 00:56:30 -0700, Ron Garret
wrote:

It occurred to me today that in fifteen years of flying I have never
once found water in my fuel when I've drained my tanks. Not a drop.
Ever. Am I just lucky, or is this really as rare an occurrence as it
seems to be? (I fly in SoCal. Maybe that has something to do with it.)

Wellll... From good old Michigan where we can easily see 30 degrees
change between night and day, day after day that can amount to a lot
of condensation. Keeping tanks full or nearly so seems to take care
of the problem but half full with the plane in a steel hangar with a
concrete floor usually means water in the thanks.

Stored indoors, if you can call an unheated steel hangar indoors (at
least it's out of the rain) particularly in the spring where the
humidity is usually very high and temperature swings can be 50 or more
degrees between day and night although 30 is typical (50 day, 30
night The next 10 days are showing mostly 40's in the day and teens
to 20s at night) I have taken over a pint out of 25 gallon tanks that
were about 1/4 full.

Outdoors is little different unless the cap seals are leaking which
does happen on Bonanza/Debonair caps. In that case they serve as great
substitutes for funnels and even full tanks get ...fuller:-)) The
gas gets displaced and the water collects.

I had to store the Deb outside while they were redoing the taxiways a
few years back. We had quite a bit of rain during that period and I
was getting one to two pints a day with full tanks. A quick trip to
the FBO took care of that. At least I know from that and flying in
torrential rain the window and door seals work well. :-))



rg
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

On Sun, 16 Mar 2008 12:14:53 -0700 (PDT),
wrote:

On Mar 15, 11:49 am, "Bob Gardner" wrote:
Depends on where you live and the design/condition of the fuel caps. Some
older Cessna fuel caps were notorious for letting water into the tanks.


There's an AD on those caps. The gaskets must be inspected every
year. The gasket (an O-ring) shrinks and cracks with age and exposure
to the sun's heat. If the gasket gets bad enough, the low pressure
atop the wing can suck air out of the tanks faster than the vent can
replace it and bladder tanks will collapse, forcing the fuel overboard

You don't need bladder tanks for that. Some years back I took off on
36. Where 36 crosses 06/24 there is slight rise and that is right
where I rotate. I did a rater agressive rotation into a steep climb.
That was the point where I discovered the caps on both tip tanks were
in need of adjusting. (They felt fine in the preflight, they are like
a thermos bottle top). Both caps blew off at the same instant. Both
tanks were *DRY* by the time I could make it around a tight pattern to
land. Each holds 15-16 gallons. At today's prices that pattern took
over $150 worth of gas not counting what went through the engine.

while the rising bladder bottom lifts the fuel sender float and makes
the gauge read full. Things can get quiet in a little while.
There are kits available to replace the flush cap with a
raised cap, like those found on the 172, and they don't let water in
nearly so much. They have a decent rubber gasket, not an O-ring.

Tanks that aren't full can promote condensation. Mostly it's a
problem on airplanes parked outside where the wings suffer wide
temperature swings between day and night. As the tanks cool (radiative
cooling into a clear sky can really aggravate it) moist air is drawn
in. As cooling progresses further, the moisture condenses out of that
air onto the tank walls, where it runs down and under the fuel. Next
morning, the sun heats the tanks, drives some of the now-drier air out
and leaving the water behind, and makes room for another load that
evening. Airplanes that sit outside for many weeks in humid areas will
get water in the tanks.

Some airplanes don't have sump drains. Sounds stupid, but the
manufacturers can get away with it. Both of the Citabrias we bought
had plugs in thos sump drains, which we replaced with drain valves.
The fuel selector on most Cessna 172/182 and others has a plug in it
too, that's supposed to come out every 100 hours. Most won't bother.
It gets a drain valve, too. Look under the belly, about under the
front of the copilot's seat.

Sometimes you don't get the water out. Bladder-type tanks
can have lateral wrinkles that prevent the water's flowing to the
sump. There's another Cessna AD on that issue. If the wrinkles trap
enough water, turbulence can dislodge it and it ends up filling the
strainer to the point that the carb gets it. Silence ensues.

Some carbs have really small metering jets that won't pass a
droplet of water, due to its surface tension. Not a good scene at all.
More silence. One drop can ruin your whole day. Many carbs have drain
plugs that should come out once in a while to clear out the
accumulated small bits that get past filters, and any water. The
metering jet is a little above the bottom of the float bowl, so some
water can exist in there until it becomes enough to cause trouble.

Water that sits in a tank long enough can absorb the blue dye and
some of the odor. Beware.

Water left in aluminum tanks will corrode them. We've found
corrosion products and pitting in fuel strainer bowls, indicating that
some owners don't bother draining them, and their mechanics never take
them apart. False economy of the worst sort.

Water in fuel come in three forms: dissolved (all fuel has a
little), entrained (suspended water droplets) and free water, the
stuff we find in the test cup. Dissolved water can precipitate into
what looks like "snow" in the fuel in cold weather and plug filters.
Entrained water will do that, too. Neglected free water can freeze in
drain valves and fuel lines, or just plain stop the engine.

Winter mogas, the stuff "without" ethanol, has a little ethanol
in it to prevent line freezup in cars. Seems to work ok in airplanes,
too. It amounts to less than 1%, they tell me. I wouldn't trust it so
much that I don't check for water. Automobile tanks are a different
setup than in airplanes. Controlled venting through filter canisters,
underneath the car where radiative cooling is no hassle, filters that
won't pass water, and so on.


Dan
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

"Roger" wrote:


Stored indoors, if you can call an unheated steel hangar indoors (at
least it's out of the rain) particularly in the spring where the
humidity is usually very high and temperature swings can be 50 or more
degrees between day and night although 30 is typical (50 day, 30
night The next 10 days are showing mostly 40's in the day and teens
to 20s at night) I have taken over a pint out of 25 gallon tanks that
were about 1/4 full.

Hmm... I don't understand this.

One cubic meter (about 264 gallons ) of saturated air at 32 degrees F.
contains about 5 to 6 grams of water vapor. The fact that the temperatures
were falling into the 20s indicates that the air had less moisture in it than
that. There couldn't have been even a gram of water in 17 gallons of air at
those temperatures.

Where was the water coming from?

--
Dan
T-182T at BFM

"Dan Luke" wrote in
:


"Roger" wrote:


Stored indoors, if you can call an unheated steel hangar indoors (at
least it's out of the rain) particularly in the spring where the
humidity is usually very high and temperature swings can be 50 or
more degrees between day and night although 30 is typical (50 day,
30 night The next 10 days are showing mostly 40's in the day and
teens to 20s at night) I have taken over a pint out of 25 gallon
tanks that were about 1/4 full.

Hmm... I don't understand this.

One cubic meter (about 264 gallons ) of saturated air at 32 degrees F.
contains about 5 to 6 grams of water vapor. The fact that the
temperatures were falling into the 20s indicates that the air had less
moisture in it than that. There couldn't have been even a gram of
water in 17 gallons of air at those temperatures.

Where was the water coming from?

It was probably suspended in the fuel.


Bertie

On Mar 18, 11:34*pm, "Morgans" wrote:
"WilliamHung" wrote

I've never come across any either, but my experience is limited.
How do the big boys check for water, the Boeings and the Busses?

William, the big difference here, is the fact that jet fuel, kerosene and
diesel fuel all have the ability to absorb moisture right out of the air,
and to dissolve the water in the fuel with no line of separation, like
happens with gas and water.

Right off hand, I would guess that there would be a point where it could no
longer absorb it all but I don't know for sure, right or wrong.
--
Jim in NC

Thanks Jim. Makes sense.

Wil