Leaking LS3a water ballast valve

Nicholas Kennedy

unread,

Jul 21, 2021, 1:47:08 PM7/21/21

to

Gents
Need some help here please.
As the title says my right water ballast valve is dripping, not super bad but annoying.drip drip drip drip
You cannot see it or touch it with your finger, it's too far up in the wing.
Inaccessible, Its like they built the wing around it.
Here is what I have tried:
Held the valve open and bathed in in Silicone spray.
Tightened up the spring tension on it.
Rotated the valve.
I can't find a drawing of it but I imagine it to be like a cylinder head valve, tulip shaped. I would imagine the valve sets on a rubber seal, could be wrong about this thou.
I wonder if there is any chemical I could put in the water that wouldn't damage the ballast bag, that might cause the interface of the valve and seat to swell up a little, enough to seal it.
Any ideas?
I'm not going to take a grinder to the wing and cut it out.
Thanks in advance
Nick
T

Papa3

unread,

Jul 21, 2021, 2:12:46 PM7/21/21

to

Hey Nick,

We have an LS3 project in the shop; I'll go look at it in the next few days and let you know if anything obvious leaps to mind. Do you happen to know if it uses the same setup as the LS4? In that ship, the sliding ball valves seat on a rubber ring which gets stiff over time. I took the whole valve assembly apart (not fun) and managed to find a close fit with some new synthetic rubber that was much more compliant. That seemed to do the trick. If you can get a boroscope in through the filler port you might be able to see what's back there. I know folks have used various rubber rejuvenators like this to restore some of the flexibility and stickiness of natural and synthetic rubber:

https://www.amazon.com/MG-Chemicals-408A-125ML-Rubber-Liquid/dp/B008O9X3KS

Nicholas Kennedy

unread,

Jul 21, 2021, 6:14:08 PM7/21/21

to

P3
Please take a look at that LS3 wing you got in the shop and see what you find.
See if that valve is accessible. To me it looks like it was layed in one wing half before they were bonded together.
That Rubber Renu might be worth a try on a long Q-Tip.
Thank you
Nick
T

John Sinclair

unread,

Jul 21, 2021, 6:53:54 PM7/21/21

to

Nick,
The valve is outboard of the dump hole about 8” or so.The valve is a 1” plastic ball on a stick, you see the stick coming out of the root rib. Don’t know any easy way to get to the ball? One might try a grease-gun with a flexible hose. Stick the flex hose in as far as it’ll go, open the valve and give her several pumps………follow that up with a rag on a flex shaft and twist it several times after the rag hits a stop. Hoping to get grease on the seal?
This is a pure WAG on my part, but probably worth a try!
JJ
WAG = wild-ass guess

Chris Runeckles

unread,

Jul 22, 2021, 12:17:56 AM7/22/21

to

Re leaking dump valve on LS3
It is possible to dismantle the dump valve with some difficulty, you need a small arm to get in the root rib hole, undo the bag neck collar nut, and push bag and plastic fitting clear of the fixed dump valve. extend the retrieve rope if its not long enough, pull out the bag through the root rib, by folding in three as it enters the rib, do not loose the retrieve / tension rope !
the rubber boot on the actuating rod is held on by two jubilee clamps and then the stick and ball end can be pushed into the valve to remove it.
when the ball is out the rubber seal can be replaced and the process reversed, the process takes a day for each valve and is a pain in the Arm ! (and else where)
DG / LS carry spare parts for these valves
Chris Runeckles . Western Australian Sailplane Products

Brian

unread,

Jul 22, 2021, 9:54:10 AM7/22/21

to

I am assuming it is leaking when the valve is closed.
I recently repaired my LS6 valve, but it was only leaking when the valve was open for filling or dumping (not much of an issue).
Found the plastic tube for the actuator arm cracked causing it to leak.
Interesting on mine there is no o-ring or seal on the actuator arm so the only thing to keep it from leaking when the valve is open is the rubber billow over the actuator arm attached with the Hose clamps. My actuator harm showed significate corrosion on it. Probably was not an issue since there is no seal that runs on the actuator arm.

In mine the it was required to cut the valve assembly to remove the ball and access the main o-ring.

Brian

John Sinclair

unread,

Jul 22, 2021, 10:11:04 AM7/22/21

to

Thanks, Chris
Good to know info. Guess the rubber seal must be removed and replaced all by feel, because the seal is facing outboard and the root rib hole is filled up with your arm?

If the clamp on the rubber boot was removed, you could then rotate the ball and shaft in place, in hopes of spreading any grease around the seal. I think I would try greasing the ball first, before paying DG their blood money for supporting LS, then waiting months for a new seal to appear!

Greetings from this side of the big pond, have fond memories of working with Australian photo interpreters during the festivities in Nam.
JJ

Papa3

unread,

Jul 22, 2021, 12:22:01 PM7/22/21

to

So, Chris confirms my suspicion (fear) that this is the same as the LS4. I still have scars on my knuckles and forearm from the one time I did this repair on an LS4.

Nick, not much I can add at this point. IF you can find a strong person without a lot of muscle bulk in the forearms (seriously), then there's a chance you can get the locking collar off and start removing all the bits and pieces. My friend who helped me called it "something akin to equine gynecology."

Because of the way the the boot is configured, I think the only way to get any goop up there (without disassembly) would be going in through the dump orifice. If I have time (maybe on Sunday) I'll try to run my boroscope up into the LS3 in the shop and see if there's a good way to a) get a look at the rubber seal and b) get some "goop" in there.

P3

Dave Nadler

unread,

Jul 22, 2021, 9:08:34 PM7/22/21

to

Nick, do not apply homeopathic chemicals, excellent guidance from Chris
below. But, do consider, this is a vintage LS aircraft, and if it
doesn't leak, it will no longer be authentic, which will no doubt reduce
its market value.

Chris Runeckles

unread,

Jul 23, 2021, 12:46:28 AM7/23/21

to

I agree with Dave I would not be putting large quantities of grease any where near the bags and dump valves, some time the bags have a plastic lining and all of the dump valve is plastic and EPDM rubber, the grease could react with plastic / rubber seal and kill it !
Chris R.

Nicholas Kennedy

unread,

Jul 23, 2021, 2:32:15 PM7/23/21

to

> I agree with Dave I would not be putting large quantities of grease any where near the bags and dump valves, some time the bags have a plastic lining and all of the dump valve is plastic and EPDM rubber, the grease could react with plastic / rubber seal and kill it !
> Chris R.

Chris R
Thanks for tutorial on how that valve works and how to fix it.
My hand is too large to go into the hole though.
I don't want to use any chemicals that might damage those bags as they are so expensive.
It drips about a gallon in 4 hours so I'll just continue putting a little more water in that side for now and live with it.
Thanks to all for the responses and ideas!
Fly safe in 2021
Nick
T