Hydraulic Brake Problems Mystery!

[John Sullivan]

I too have experienced the problem you are having with my
Ventus which was manufactured in 2004. It took me a long
time to figure out what was wrong. Eventually I simply
worked my way through the system to discover that
everything free as it should be except for the master cylinder
plunger which was frozen in the body of the housing. I
removed the unit, withdrew the actuating plunger, cleaned it
and then put silicone grease on it. That was the fix! Now I
will grease it every year at the annual…

John Sullivan, UFO

[Annemarie Hollestelle]

On Mar 28, 10:46*pm, John Sullivan
> wrote:
> I too have experienced the problem you are having with my
> Ventus which was manufactured in 2004. *It took me a long
> time to figure out what was wrong. *Eventually I simply
> worked my way through the system to discover that
> everything free as it should be except for the master cylinder
> plunger which was frozen in the body of the housing. *I
> removed the unit, withdrew the actuating plunger, cleaned it
> and then put silicone grease on it. *That was the fix! *Now I
> will grease it every year at the annual
>
> John Sullivan, UFO

Please be advised that the European glider manufacturers use DOT4
(yellow) "car" brake fluid in their disc brake systems. If you use
the(red) "aviation" type mill spec. brake fluid in these systems all
your "O" rings will swell and your brake system will be seized !
Please check with the glider manufacturer before you add the wrong
fluid!
Ed Hollestelle, A1

[Peter Scholz[_3_]]

Am 30.03.2011 18:00, Annemarie Hollestelle wrote:
> On Mar 28, 10:46 pm, John Sullivan
> > wrote:
>> I too have experienced the problem you are having with my
>> Ventus which was manufactured in 2004. It took me a long
>> time to figure out what was wrong. Eventually I simply
>> worked my way through the system to discover that
>> everything free as it should be except for the master cylinder
>> plunger which was frozen in the body of the housing. I
>> removed the unit, withdrew the actuating plunger, cleaned it
>> and then put silicone grease on it. That was the fix! Now I
>> will grease it every year at the annual
>>
>> John Sullivan, UFO
>
> Please be advised that the European glider manufacturers use DOT4
> (yellow) "car" brake fluid in their disc brake systems. If you use
> the(red) "aviation" type mill spec. brake fluid in these systems all
> your "O" rings will swell and your brake system will be seized !
> Please check with the glider manufacturer before you add the wrong
> fluid!
> Ed Hollestelle, A1
>

Be careful, this is not true for all European gliders. E.g. my
Schleicher ASW24 uses Aeroshell Fluid 4, which is bases on mineral oil.
Using car brake fluid would ruin the system. The difference lies in
where the brake system comes from:

Aircraft brake system (Cleveland): mineral oil based fluid
Motorcycle brake system: DOT... car brake fluid

--
Peter Scholz
ASW24 JE

[Andy[_1_]]

On Mar 30, 9:56*am, Peter Scholz > wrote:
> Am 30.03.2011 18:00, Annemarie Hollestelle wrote:
>
>
>
>
>
> > On Mar 28, 10:46 pm, John Sullivan
> > > *wrote:
> >> I too have experienced the problem you are having with my
> >> Ventus which was manufactured in 2004. *It took me a long
> >> time to figure out what was wrong. *Eventually I simply
> >> worked my way through the system to discover that
> >> everything free as it should be except for the master cylinder
> >> plunger which was frozen in the body of the housing. *I
> >> removed the unit, withdrew the actuating plunger, cleaned it
> >> and then put silicone grease on it. *That was the fix! *Now I
> >> will grease it every year at the annual
>
> >> John Sullivan, UFO
>
> > Please be advised that the European glider manufacturers use DOT4
> > (yellow) "car" brake fluid in their disc brake systems. If you use
> > the(red) "aviation" type mill spec. brake fluid in these systems all
> > your "O" rings will swell and your brake system will be seized !
> > Please check with the glider manufacturer before you add the wrong
> > fluid!
> > Ed Hollestelle, A1
>
> Be careful, this is not true for all European gliders. E.g. my
> Schleicher ASW24 uses Aeroshell Fluid 4, which is bases on mineral oil.
> Using car brake fluid would ruin the system. The difference lies in
> where the brake system comes from:
>
> Aircraft brake system (Cleveland): mineral oil based fluid
> Motorcycle brake system: DOT... car brake fluid
>
> --
> Peter Scholz
> ASW24 JE- Hide quoted text -
>
> - Show quoted text -

From what others have said on this group it's not quite that simple.
It seems some glider manufacturers chose to use a Cleveland wheel
assembly but mate it with a non aircraft master cylinder. The master
cylinder then forces auto style fluid to be used and that's
incompatible with the Cleveland caliper seals so they get changed to a
different type.

Of course the simple answer is to read the glider's maintenance manual
but I know that's a last resort ;)

Andy (ASW 28)

[James Thomson[_2_]]

>From what others have said on this group it's not quite that simple.
>It seems some glider manufacturers chose to use a Cleveland wheel
>assembly but mate it with a non aircraft master cylinder. The master
>cylinder then forces auto style fluid to be used and that's
>incompatible with the Cleveland caliper seals so they get changed to a
>different type.
>
>Of course the simple answer is to read the glider's maintenance manual
>but I know that's a last resort ;)
>
>Andy (ASW 28)
>
The ONLY safe way is to read the manual! Source of the glider or wheel
caliper maker is not a safe guide to the correct fluid.

The ASK-21 uses Cleveland parts throughout - and red aviation fluid

The DG-505 uses a Tost (aircraft) master cylinder and a Cleveland caliper
(with changed seals) and DOT4 car fluid.

Tost offer a range of master cylinders which use DOT4, they then confuse
things by offering their own caliper (DOT4) and Cleveland parts for either
DOT4 or red fluid! Only your own handbook can tell you what to use.

[seventripleone]

The only safe way may be to look what's already in the system.
(Everything else than red color means .4 IMHO).

For Cleveland/Parker brake calipers delivered by Tost to non-
Schleicher manufacturers: they are ex-factory equipped with o-rings
for mineral/"Aeroshell" oil and "converted" to .4 (= o-rings
exchanged). These calipers receive a big red (removable) label that
says DOT4 and get a little "O" stamped to the outside (diam. ~ 5mm,
permanent) which may be hidden by other hardware when the caliper is
mounted to the glider.

[Andy[_1_]]

On Mar 31, 5:55*am, seventripleone > wrote:

> The only safe way may be to look what's already in the system.
> (Everything else than red color means .4 IMHO).

Absolutely not! Unless you are the sole owner of the glider since
new, and unless no one except you has ever maintained it, you have no
idea whether someone else has contaminated the system with the wrong
fluid.

Maintenance manual first, then if the color does not agree, a careful
review of the maintenance logs to see if the system has been
modified. If the color does not match and there is no record of
modification you could be in for a complete brake system overhaul.

Andy