Stopping a Tail Tank Drip

Need some advice for stopping a drip (once per 20 seconds) from a tail
tank. I’m aware of using Vaseline / Chapstick / beeswax on under wing
dump valves, but what about on a tail tank? How would you even reach
it to goop it up (the seat is way up a 8 mm tube)?

The tank in question is a 5.5 liter slip-in tank on an LS8. It hadn’t
dripped at all until last weekend, when the temperature was around 5 C
(no worry about freezing, I was ridge running). I didn’t check the
tension on the cable, so maybe the problem will go away when
reasonable soaring weather returns.

Any thoughts would be appreciated.

-John

On Nov 24, 12:39*pm, jcarlyle wrote:
Need some advice for stopping a drip (once per 20 seconds) from a tail
tank.

I'm in the same boat. I emptied out the tank and blew air up into the
line from the bottom and then filled it again and the drip was gone.
I head dirt/debris move around inside the tank and figure that was not
allowing the valve to close completely on my ASW-20B tail tank. That
said, anyone have any good idea how to clean out one of these tanks?
You might have the same problem.

Good luck.
Bruno - B4

On Nov 24, 2:23*pm, Bruno wrote:
On Nov 24, 12:39*pm, jcarlyle wrote:

Need some advice for stopping a drip (once per 20 seconds) from a tail
tank.

I'm in the same boat. *I emptied out the tank and blew air up into the
line from the bottom and then filled it again and the drip was gone.
I head dirt/debris move around inside the tank and figure that was not
allowing the valve to close completely on my ASW-20B tail tank. *That
said, anyone have any good idea how to clean out one of these tanks?
You might have the same problem.

Good luck.
Bruno - B4

Be careful blowhards blow up tanks,

Happy Thanksgiving

Richard.
www.craggyaero.com

On Wed, 24 Nov 2010 14:23:59 -0800, Bruno wrote:

I'm in the same boat. I emptied out the tank and blew air up into the
line from the bottom and then filled it again and the drip was gone. I
head dirt/debris move around inside the tank and figure that was not
allowing the valve to close completely on my ASW-20B tail tank. That
said, anyone have any good idea how to clean out one of these tanks? You
might have the same problem.

Have you guys seen the valve used in your tail tanks? Could the valve be
held open by slipping a thin plastic rod up the drain while you flush the
tank out?

Your local friendly RC model shop sells a rod that would probably do the
trick if the valve design is one that wouldn't be damaged by it: its the
core of the plastic Bowden Cables used to connect a servo to its control
surface. Its quite stiff and somewhere between 2 and 3 mm in diameter.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Nov 24, 5:23*pm, Bruno wrote:
On Nov 24, 12:39*pm, jcarlyle wrote:

Need some advice for stopping a drip (once per 20 seconds) from a tail
tank.

I'm in the same boat. *I emptied out the tank and blew air up into the
line from the bottom and then filled it again and the drip was gone.
I head dirt/debris move around inside the tank and figure that was not
allowing the valve to close completely on my ASW-20B tail tank. *That
said, anyone have any good idea how to clean out one of these tanks?
You might have the same problem.

Good luck.
Bruno - B4

Depends what's in there. Step one: remove tank, inspect.

My 20B has a welded aluminum tank that required major work two years
ago to restore to service. New electric valve, some cutting &
welding. Cleaning, blasting, corrosion proofing and sealing with fuel
tank sealer. Works great since, no leaks.

-Evan Ludeman / T8

Martin - keeping the valve open is easy, I just use the lever in the
cockpit. Filling pressure is limited to a 1 meter head, but maybe
filling and dumping repeatedly will clear out anything in there. The
funnel has a fine mesh, so it's hard to see how junk could have gotten
inside the tank.

Bruno, Evan - unlike your tanks, my tank is plastic, so no oxide
worries. Getting it out is a little involved, but the maintenance
manual has clear instructions. That's a last resort, though. Sounds
like you may have no options, though, Bruno.

I'll check the cable tension leading to the valve this weekend. If
it's tight in the closed position, I bet the drip is due to cold
weather.

Meanwhile, anyone have any ideas on how to apply Vaseline to a valve
seat located some distance up an 8 mm tube?

-John

I'll check the cable tension leading to the valve this weekend. If
it's tight in the closed position, I bet the drip is due to cold
weather.

Meanwhile, anyone have any ideas on how to apply Vaseline to a valve
seat located some distance up an 8 mm tube?

-John


Know any pilots who are gynecologists?

On Nov 24, 9:47*pm, jcarlyle wrote:
Martin - keeping the valve open is easy, I just use the lever in the
cockpit. Filling pressure is limited to a 1 meter head, but maybe
filling and dumping repeatedly will clear out anything in there. The
funnel has a fine mesh, so it's hard to see how junk could have gotten
inside the tank.

Bruno, Evan - unlike your tanks, my tank is plastic, so no oxide
worries. Getting it out is a little involved, but the maintenance
manual has clear instructions. That's a last resort, though. Sounds
like you may have no options, though, Bruno.

I'll check the cable tension leading to the valve this weekend. If
it's tight in the closed position, I bet the drip is due to cold
weather.

Meanwhile, anyone have any ideas on how to apply Vaseline to a valve
seat located some distance up an 8 mm tube?

-John

Hi John,

I have the same problem and I believe we have the same exact tail
tank. My temporary solution involves a foam ear plug stuff into the
tail tube. Suprisingly, it stays put, yet the head from the tank is
enough to eject it when the valve is opened. Since I'm always within
the aft CG limit, there's no safety risk if it doesn't drain (except
for cold weather, and I fly dry when it's close to freezing). But,
I'm planning to pull the tank this winter and do a proper inspection
and adjustment/repair as needed.

P3

Hi, Erik,

That's a very ingenious temporary solution! I would've never thought
of that trick.

Your glider and mine are pretty similar in age. I wonder if the drip
problem is something that strikes LS8s with the 5.5 liter tail tank
over a certain age. I think the LS6 used a similar tank - any LS6
owners experiencing something similar?

Good luck with the rework, Erik. If you think of it, take some
pictures of the valve to document the problem.

-John

On Nov 25, 10:28 am, Papa3 wrote:
Hi John,

I have the same problem and I believe we have the same exact tail
tank. My temporary solution involves a foam ear plug stuff into the
tail tube. Suprisingly, it stays put, yet the head from the tank is
enough to eject it when the valve is opened. Since I'm always within
the aft CG limit, there's no safety risk if it doesn't drain (except
for cold weather, and I fly dry when it's close to freezing). But,
I'm planning to pull the tank this winter and do a proper inspection
and adjustment/repair as needed.

P3

Your glider and mine are pretty similar in age. I wonder if the drip
problem is something that strikes LS8s with the 5.5 liter tail tank
over a certain age. I think the LS6 used a similar tank - any LS6
owners experiencing something similar?

Is there anything that would be destroyed by putting a CLR solution in
the tank and letting it soak? By your and others descriptions my
guess is that there are water deposit/oxidation buildups preventing
the valve from being able to completely seat, which could be dissolved
with a CLR treatment. Among other materialsn it's list of materials
it's rated safe to use on is fiberglass, and there are even directions
for using it in coffee makers so it's not terribly caustic although it
is very effective at dissolving the stuff it was designed for -Calcium/
Lime/Rust.

-Paul