Hi all,

I am curious as to others peoples experience with replacing leaking rubber bellows in the water ballast systems on 18m Schempp Hirth gliders. I have a Ventus 2CX glider that according to the logbook has had the rubber bellows replaced regularly over its
life. IE about every year at least one of the four need replacement. The replacement for the inner bellows is particularly difficult as I understand the standard practice is to cut a hole in wings to accomplish this. It appears to be a regular problem
for Australian based gliders and one of the theories is the quality of our water and its affect on the rubber. When removed they appear to be swollen to the point that the resilience of the seal is compromised to the extent they will not hold a seal to
prevent water escaping. Note in Australia we are required to test the integrity of the ballast tanks every year which requires pressurising the ballast tanks with 125mm of water pressure and checking for any loss in air pressure over 10 minutes which is
impossible to achieve with even a slightly deteriorated bellows.

Is this a problem for European and American owners of Schempp Hirth gliders as well? Please tell me your experience of replacing the rubber bellows. Is this a regular problem and how have you replaced the inner bellows.

regards

Andrew

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fredag den 28. juli 2023 kl. 04.25.03 UTC+2 skrev Andrew Herwig:

Hi all,

I am curious as to others peoples experience with replacing leaking rubber bellows in the water ballast systems on 18m Schempp Hirth gliders. I have a Ventus 2CX glider that according to the logbook has had the rubber bellows replaced regularly over

its life. IE about every year at least one of the four need replacement. The replacement for the inner bellows is particularly difficult as I understand the standard practice is to cut a hole in wings to accomplish this. It appears to be a regular
problem for Australian based gliders and one of the theories is the quality of our water and its affect on the rubber. When removed they appear to be swollen to the point that the resilience of the seal is compromised to the extent they will not hold a
seal to prevent water escaping. Note in Australia we are required to test the integrity of the ballast tanks every year which requires pressurising the ballast tanks with 125mm of water pressure and checking for any loss in air pressure over 10 minutes
which is impossible to achieve with even a slightly deteriorated bellows.

Is this a problem for European and American owners of Schempp Hirth gliders as well? Please tell me your experience of replacing the rubber bellows. Is this a regular problem and how have you replaced the inner bellows.

regards

Andrew

Hi,

Living in Denmark and flying a 21 year old V2cT, which I've had since it was 2 years old. It's got 500+ starts and the majority of these with water.
No leaking observed so far, but I've been awaiting it to happen.

In my vicinity I've seen one much older V1b which leaked and had the repair done by cutting holes in the wings.
At one competition I was at, a Schempp Hirth (forgot if it was a Ventus or a Discus) leaked in flight leading to a large water build up in the tail of the fuselage making it almost uncontrolable to the pilot, who consequently outlanded. Why the drain
holes didn't drain it sufficiently fast I didn't get to know. It would seem like the leak rate would overwhelm their capacity.

Can you share the Australian procedure?
Applying pressurized air to inflatable water bags in wings, we've seen some spectacular mishaps causing delamination.

Regards Per

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