Discus tail ballast leak

[Dee[_2_]]

A friend of mine has a Discus cx with a leaking fin tank that has been difficult to remedy. When viewed from the fin bottom, the water does not appear to leak around the dump valve but from somewhere else. The maintenance manual has a schematic of this area. Does anyone have a suggestion as to how to gain access to the hardware just beneath the tank or perhaps there is a Discus owner group that could assist? Most discussion of tank issues relate to its wing tanks.
Thanks,
Dee

[John Sinclair[_5_]]

On Sunday, August 23, 2020 at 11:56:38 AM UTC-7, Dee wrote:
> A friend of mine has a Discus cx with a leaking fin tank that has been difficult to remedy. When viewed from the fin bottom, the water does not appear to leak around the dump valve but from somewhere else. The maintenance manual has a schematic of this area. Does anyone have a suggestion as to how to gain access to the hardware just beneath the tank or perhaps there is a Discus owner group that could assist? Most discussion of tank issues relate to its wing tanks.
> Thanks,

If the valve itself is not leaking, it’s probably the rubber boot that connects the tank to the valve...........they seldom last more than 5 years! I’d pull the rudder off and check the boot!
JJ

[Dee[_2_]]

Good lead, JJ, I see the boot in the drawing and will next remove the rudder for further inspection.
Thanks

[Mike the Strike]

On Sunday, August 23, 2020 at 9:22:35 PM UTC+1, Dee wrote:
> Good lead, JJ, I see the boot in the drawing and will next remove the rudder for further inspection.
> Thanks
I had the same problem in a Discus 2b - it was the rubber boot. You have to remove the rudder for access, but it's not a big job for someone experienced with this airframe.

Mike

[Eric Munk]

Boot is usually the suspect. An hour's work for an experienced techie to
replace. Use non-acidic thick grease like vaseline to lube before putting
it in. Saves you smaller leaks over time. Problem usually comes back after
some years depending on tailtank use, local climate etc.

[Muttley]

Just one small bit of advise when removing rudder. Make sure you have some
extensions made on the Rudder cables i.e. long plastic cable tie etc. as it is extremely difficult to fish the ends out of the fuselage if they slip into it by mistake.

[Dee[_2_]]

Great feedback guys, thank you! I now have a source to order the replacement boot. Hoping when we remove the rudder an access window won't have to be cut. We will be careful to keep outward tension on the cables.
Dee

[John Sinclair[_5_]]

On Monday, August 24, 2020 at 9:19:46 AM UTC-7, Dee wrote:
> Great feedback guys, thank you! I now have a source to order the replacement boot. Hoping when we remove the rudder an access window won't have to be cut. We will be careful to keep outward tension on the cables.
> Dee
You can make a little hook out of a coat hanger then slip it in between the fin and rudder and hook the dump valve actuating arm and give it a pull in order to seat a leaky tail valve............glad my days of dealing with leaky water valves are over!
JJ

[andy l]

On Monday, 24 August 2020 at 17:19:46 UTC+1, Dee wrote:
> Great feedback guys, thank you! I now have a source to order the replacement boot. Hoping when we remove the rudder an access window won't have to be cut. We will be careful to keep outward tension on the cables.
> Dee

No window needed. You don't need permanent tension on the cables. They only go about 4 inches forward until the swaged ferrule reaches the nylon tube sleeve, so just relax it forward, then pull out again when ready to reconnect. I use a suitable length single piece of string tied to both.

[Tim Taylor]

On Tuesday, August 25, 2020 at 9:46:18 PM UTC-6, andy l wrote:
> On Monday, 24 August 2020 at 17:19:46 UTC+1, Dee wrote:
> > Great feedback guys, thank you! I now have a source to order the replacement boot. Hoping when we remove the rudder an access window won't have to be cut. We will be careful to keep outward tension on the cables.
> > Dee
> No window needed. You don't need permanent tension on the cables. They only go about 4 inches forward until the swaged ferrule reaches the nylon tube sleeve, so just relax it forward, then pull out again when ready to reconnect. I use a suitable length single piece of string tied to both.

While you have the tail off, I do recommend checking or replacing the valve. You can overhaul the valve with a new rubber washer seal and check to see that there is a teflon or uhmw slide material on the angled ramp that opens the valve. I did both the bellows and valve at the same time last year during the PanAm. I was fortunate to have the spare parts on hand when the bellows gave out.