Pneumatics Question

On May 24, 6:32*pm, jsbrake wrote:
Hi All,
Whenever I accelerate, my varios bump up and tell me I'm climbing,
then settle back to reality. *Any idea of what I need to look for to
fix this?
My setup:
Kestrel 19, two static ports in the tail boom, pitot and TE in the
fin. *The TE line is split under the seat using a Y connector and then
travels to two varios (a Winter mechanical and a 1990-era audio/final-
glide called a VariCalc). *Pitot and static lines are split behind the
panel using T connectors.
I replaced all the non-permanent tubing last year and they all seemed
to be leak-free.
Thanks!
-John

Did it do this before you changed the non-permanent tubing?

Why was the tubing changed?

Did you do a real leak down test?

I would do the idiot test of confirming you have the vario connected
to the TE line (blow gently onto the the TE probe and confirm you hear
it affecting the electronic vario). But if you've got the static wired
to the TE you would expect the opposite of what you see. That makes me
suspect you have the TE line open to cockpit pressure somewhere. Other
options like a leak across the TE/static circuits with certain types
of TE probe/mount failure would also produce the opposite effect (i.e.
would show sink when you speed up). (And BTW thank you Mr. Greenwell I
was the idiot with the triple probe static port blocked with grease).

The variocalc has no capacity and the winter is connected to a
capacity flask. You rely on line impedance for this not to be a
problem, so good you have the TE line split far away, like under the
seat. The static and pitot lines are (obviously) irrelevant to the
vario.

It could be a TE line open to cockpit pressure. It could be a leak in
one of the varios themselves (less likely, but try taking one vario at
a time out of the pneumatic circuit). If things are leaking/open to
cockpit pressure it is hard to say for sure what they will do as you
speed up, depends on the cockpit venting. Does opening closing vents
do silly things?

I've found a nylon "T" piece once that was cracked wide open and
leaking so check things like that over carefully.

You can exclude the capacity leaking by taking the whole winter vario
out of the circuit, or you can block the capacity port on the winter
(which should then do nothing).

If all that passes, swap TE probes with another glider and test. What
type of TE probe is it?

Darryl