Airbrakes Pop Out at 115 kts

Each time that I exceed approximately 115 knots, my airbrakes partially
deploy. They come out about 2 inches (5cm) and I cannot seem to get
them to retract unless I reduce my speed, fully deploy them and then
retract them.

Any ideas?

Thanks, John (67R)

What type sailplane?

Many Schempp-Hirth style spoilers will suck open a little as the
springs on the spoiler caps get old and weak. Once lifted up, they may
catch on the wing skin and stay that way until the handle is cycled.

Not just Schemmps. Good advice. Check the springs. Also check that
overcenter for the spoiler lock is within tolerance. Don't trust the
annual to uncover such problems.

John,
You didn't say what type of aircraft, but look for air getting into the
spoiler boxes and pushing the top out into the slipstream. I am assuming
they are not unlocking, only the springs compressing.

This often comes from not having a good seal at the wing roots and air
pressure is finding its way through the wing and into the spoiler boxes.
As soon as they come up a bit, the slipstream will catch them and pull the
top out further.

Sounds like something that should possibly have been picked up at the last
airworthiness inspection.
Spring tension on the airbrake caps can be measured and corrected if need
be. Otherwise, if its the whole airbrake that is extending, then there is
either way too much free play in the system (unlikely) or the overcenter
locking is not working.
Otherwise, if it is only a recent thing, then something has changed and you
should check it before flying again.

Just my thoughts.
Cheers
Chris
Std Cirrus "C2"


"ContestID67" wrote in message
oups.com...
Each time that I exceed approximately 115 knots, my airbrakes partially
deploy. They come out about 2 inches (5cm) and I cannot seem to get
them to retract unless I reduce my speed, fully deploy them and then
retract them.

Any ideas?

Thanks, John (67R)

Maybe the onboard computer has calculated that Vne is approaching and kicks
out the spoilers.

Colin

"COLIN LAMB" wrote in message
nk.net...
Maybe the onboard computer has calculated that Vne is approaching and
kicks
out the spoilers.

Colin

Is this an Airbus glider? 8^)
-Bob

Thanks for all the advice. Setting the comments about Vne and Airbuses
aside for the moment...

Yes, these are Schempp-Hirth spoilers on a 21 year old DG-101. What
makes most sense is the springs becoming weak and/or an air leak.

I will order replacement springs from DG. The overcenter for the
spoiler lock was specifically checked at the last annual.

On the air leak - I always carefully tape the wing roots but the
aileron gap seals are shot. I have new mylar seals in hand and will be
installing them in the next few days.

After that work is done I will report back.

Thanks again, John

Also, make sure there's no air going from the fuselage, which is a high
pressure area, out through the control rods. There should be a bellows
made of a soft non-permeable material around the pushrods at the wing
root.

-Tom

John,
Have you done the "dime" test?
+ Lift the spoiler cap and slip in 4 or 5 dimes.
+ Close and lock spoilers. If the cap didn't close flush, then the rod
length after the over-center mechanism needs adjustment.
+ If the spoilers did close flush, then you need stronger springs. The
springs on the ends should be about twice as strong as the others.
JJ