Water in the fuel

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
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

"Nomen Nescio" wrote in message
...
-----BEGIN PGP SIGNED MESSAGE-----

From: Ron Garret

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.)

Oh, It's real.
I lost an engine on takeoff in my 3rd hour of solo flight as a student.
The thing
just lost power and wound down REAL quick at a few hundred ft AGL. It
caught
again after a very long 5-10 seconds and I climbed out, circled around,
and
landed without further incident. Most likely a little water in the line
and a few
tablespoons of water were drained from the tank after.
I've written it off as a **** poor fuel check by a dumbass 17 y.o. student
pilot
on the first flight of the morning.
But since then, I've been goddam careful about draining enough fuel to
find
any water in the system. And I have found some, on occasion.
It's been 35 years since then without any more problems.

And NO, I didn't need a change of underwear after I landed.
But you probably could have wrung more sweat out of my shirt than we found
in the fuel.




My C150 has had water in the tanks on several occasions.We changed
gaskets,and even caps but for
a time it continued.I would get several ounces of water
from one tank or the other.Mine is a F model and the
filler pipe has a well around it like a mote.This seems like the dumbest
idea ever.I don't know what finally corrected
the problem but it seems to have gone away for the past
6-9 months.Needless to say I am VERY careful about
checking the sumps. :-)

Bob Barker N8749S

On Mar 16, 1:11 pm, "Robert A. Barker" wrote:
"Nomen Nescio" wrote in message

...

-----BEGIN PGP SIGNED MESSAGE-----

From: Ron Garret

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.)

Oh, It's real.
I lost an engine on takeoff in my 3rd hour of solo flight as a student.
The thing
just lost power and wound down REAL quick at a few hundred ft AGL. It
caught
again after a very long 5-10 seconds and I climbed out, circled around,
and
landed without further incident. Most likely a little water in the line
and a few
tablespoons of water were drained from the tank after.
I've written it off as a **** poor fuel check by a dumbass 17 y.o. student
pilot
on the first flight of the morning.
But since then, I've been goddam careful about draining enough fuel to
find
any water in the system. And I have found some, on occasion.
It's been 35 years since then without any more problems.

And NO, I didn't need a change of underwear after I landed.
But you probably could have wrung more sweat out of my shirt than we found
in the fuel.

My C150 has had water in the tanks on several occasions.We changed
gaskets,and even caps but for
a time it continued.I would get several ounces of water
from one tank or the other.Mine is a F model and the
filler pipe has a well around it like a mote.This seems like the dumbest
idea ever.I don't know what finally corrected
the problem but it seems to have gone away for the past
6-9 months.Needless to say I am VERY careful about
checking the sumps. :-)

Bob Barker N8749S

An accident report from the Transportation Safety Board
(Canada):

http://www.tsb.gc.ca/en/reports/air/...p?print_view=1

Dan

On Mar 16, 5:46 pm, wrote:
On Mar 16, 1:11 pm, "Robert A. Barker" wrote:



"Nomen Nescio" wrote in message

.. .

-----BEGIN PGP SIGNED MESSAGE-----

From: Ron Garret

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.)

Oh, It's real.
I lost an engine on takeoff in my 3rd hour of solo flight as a student.
The thing
just lost power and wound down REAL quick at a few hundred ft AGL. It
caught
again after a very long 5-10 seconds and I climbed out, circled around,
and
landed without further incident. Most likely a little water in the line
and a few
tablespoons of water were drained from the tank after.
I've written it off as a **** poor fuel check by a dumbass 17 y.o. student
pilot
on the first flight of the morning.
But since then, I've been goddam careful about draining enough fuel to
find
any water in the system. And I have found some, on occasion.
It's been 35 years since then without any more problems.

And NO, I didn't need a change of underwear after I landed.
But you probably could have wrung more sweat out of my shirt than we found
in the fuel.

My C150 has had water in the tanks on several occasions.We changed
gaskets,and even caps but for
a time it continued.I would get several ounces of water
from one tank or the other.Mine is a F model and the
filler pipe has a well around it like a mote.This seems like the dumbest
idea ever.I don't know what finally corrected
the problem but it seems to have gone away for the past
6-9 months.Needless to say I am VERY careful about
checking the sumps. :-)

Bob Barker N8749S

An accident report from the Transportation Safety Board
(Canada):

http://www.tsb.gc.ca/en/reports/air/...157.asp?print_...

Dan

"Due to the location of the gascolator drain valve, it was hard for
the pilot to collect the fuel flowing out of it to assess its
condition."

If you're solo good luck unless you have a bucket.

Anyone have an ingenious method for collecting C172 engine sump
sample?


Dan Mc

On Mar 15, 3:15*pm, Bertie the Bunyip wrote:
William Hung wrote in news:ed9d1365-dc16-4b4e-9941-
:

On Mar 15, 3:56*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 never come across any either, but my experience is limited.

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

Same way, but less frequently. Much less frequently.

Bertie

Considering the "air space" available in their tanks, one would think
that condensation would be a problem. I don't remember ever seeing
gascolators on the big ones. Where are they at?

Wil

wrote in message
...
On Mar 16, 1:11 pm, "Robert A. Barker" wrote:
"Nomen Nescio" wrote in message

...



My C150 has had water in the tanks on several occasions.We changed
gaskets,and even caps but for
a time it continued.I would get several ounces of water
from one tank or the other.Mine is a F model and the
filler pipe has a well around it like a mote.This seems like the dumbest
idea ever.I don't know what finally corrected
the problem but it seems to have gone away for the past
6-9 months.Needless to say I am VERY careful about
checking the sumps. :-)

Bob Barker N8749S

An accident report from the Transportation Safety Board
(Canada):

http://www.tsb.gc.ca/en/reports/air/...p?print_view=1

Dan

Very interesting.I can reach from the linkage under the
cowl to the colater drain and have only found a couple
of drops of water during all of the time I had problems
with the water in the tanks.I usually rock the plane hard
and let it settle 3 or 4 minutes prior to sumping the tanks.

Bob Barker N8749S

William Hung wrote in news:c180217b-4f15-406d-862a-
:

On Mar 15, 3:15*pm, Bertie the Bunyip wrote:
William Hung wrote in news:ed9d1365-dc16-4b4e-
9941-
:

On Mar 15, 3:56*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 never come across any either, but my experience is limited.

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

Same way, but less frequently. Much less frequently.

Bertie

Considering the "air space" available in their tanks, one would think
that condensation would be a problem. I don't remember ever seeing
gascolators on the big ones. Where are they at?

In the wing roots foro the wing tanks and underneath the fuselage for
the center, but we never check them ourselves. In fact I don't know how
often they do get checked, but I do know it isn't often. I'll ask the
guys next time I go out.


Bertie

On Mar 16, 3:18 pm, Dan wrote:

"Due to the location of the gascolator drain valve, it was hard for
the pilot to collect the fuel flowing out of it to assess its
condition."

If you're solo good luck unless you have a bucket.

Anyone have an ingenious method for collecting C172 engine sump
sample?

Dan Mc

We do it all the time. There's a small tube off the strainer
(or should be), and if you stick the sample cup over it and reach up
and yank the strainer drain, you can catch it. It's a bit of a reach
but even our small students manage it. I have a harder time, not
because of short arms, but because I'm getting stiffer in the low back
and hips and such gymnastics cost me some.
But most people don't bother. If they do anything at all, they
just dribble a little squirt onto the pavement and let it go at that,
assuming that they've cleared out any water. But if the strainer was
three-quarters full of water, they've just lowered the level a little.
And if it was three-quarters full, the rest of the system might have
lots laying in it, enough to overwhelm the strainer when it arrives.
Or if the weather's really cold, the frozen entrained water ("snow")
might be there, and they don't notice it. Until it plugs the screens
in the strainer or carb inlet.
I'd rather have the Citabria's setup: strainer drain cock that
sticks out of the side of the cowl. Push and catch. Simple and cheap,
but not so sleek.

Dan

On Mar 16, 7:35 pm, wrote:
On Mar 16, 3:18 pm, Dan wrote:

"Due to the location of the gascolator drain valve, it was hard for
the pilot to collect the fuel flowing out of it to assess its
condition."

If you're solo good luck unless you have a bucket.

Anyone have an ingenious method for collecting C172 engine sump
sample?

Dan Mc

We do it all the time. There's a small tube off the strainer
(or should be), and if you stick the sample cup over it and reach up
and yank the strainer drain, you can catch it. It's a bit of a reach
but even our small students manage it. I have a harder time, not
because of short arms, but because I'm getting stiffer in the low back
and hips and such gymnastics cost me some.
But most people don't bother. If they do anything at all, they
just dribble a little squirt onto the pavement and let it go at that,
assuming that they've cleared out any water. But if the strainer was
three-quarters full of water, they've just lowered the level a little.
And if it was three-quarters full, the rest of the system might have
lots laying in it, enough to overwhelm the strainer when it arrives.
Or if the weather's really cold, the frozen entrained water ("snow")
might be there, and they don't notice it. Until it plugs the screens
in the strainer or carb inlet.
I'd rather have the Citabria's setup: strainer drain cock that
sticks out of the side of the cowl. Push and catch. Simple and cheap,
but not so sleek.

Dan

The C172E has a gasculator that requires you open the cowling and
reach down or reach up underneath the opening behind the nosewheel.

I'm 6'1" and there's no way I can reach the release on the left side
of the panel and the drain underneath the gasculator on the right side
of the nosewheel. You'd need 10' arms to do that.

The 172N has the drain control next to the oil dipstick (top access
panel). That I can reach, though ridiculous gyrations are required.

The Bonanzas have a good setup -- small access panel at the lowest
point in the system with a quick drain.


Dan Mc

wrote:
On Mar 16, 3:18 pm, Dan wrote:


"Due to the location of the gascolator drain valve, it was hard for
the pilot to collect the fuel flowing out of it to assess its
condition."

If you're solo good luck unless you have a bucket.

Anyone have an ingenious method for collecting C172 engine sump
sample?

Dan Mc


We do it all the time. There's a small tube off the strainer
(or should be), and if you stick the sample cup over it and reach up
and yank the strainer drain, you can catch it. It's a bit of a reach
but even our small students manage it. I have a harder time, not
because of short arms, but because I'm getting stiffer in the low back
and hips and such gymnastics cost me some.
But most people don't bother. If they do anything at all, they
just dribble a little squirt onto the pavement and let it go at that,
assuming that they've cleared out any water. But if the strainer was
three-quarters full of water, they've just lowered the level a little.
And if it was three-quarters full, the rest of the system might have
lots laying in it, enough to overwhelm the strainer when it arrives.
Or if the weather's really cold, the frozen entrained water ("snow")
might be there, and they don't notice it. Until it plugs the screens
in the strainer or carb inlet.
I'd rather have the Citabria's setup: strainer drain cock that
sticks out of the side of the cowl. Push and catch. Simple and cheap,
but not so sleek.

Dan

I can't imagine being able to pull the strainer in a 172 and reach down
and grab a sample at the same time (but I'm short). My primary
instructor always had me look at the sample as it was straining to see
how quickly it evaporated. He pulled the strainer and then put some
water out and there is a difference. Now if it was 90% avgas and 10%
water I probably wouldn't have noticed at all.

Margy