Speed Brakes

flyingcheesehead

flyingcheesehead

Touchdown! Greaser!
Joined
Feb 23, 2005
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UQACY, WI
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iMooniac
Hi folks,

I had an interesting situation the other day... Asymmetric speed brake deployment. Wasn't nearly as big a deal flying-wise as I'd expected, I doubt it even took 1/3 rudder to counteract, but it was interesting.

I'm wondering if there are any insights as to why one would fail, and what maintenance can be done to it or preventative actions taken. I'm assuming that the very cold weather being here now has something to do with it. No moisture prior to that (and I'm in a very well-sealed hangar, though it's unheated).

Anything that can be done short of pulling 'em out of the wings and sending 'em back to Precise Flight? FWIW, these are the factory-installed ones on the Mooney Ovation. Also, after landing I tried again and a couple tries later, they worked. Haven't tried since.

Thanks!
 
flyingcheesehead said:
Hi folks,

I had an interesting situation the other day... Asymmetric speed brake deployment. Wasn't nearly as big a deal flying-wise as I'd expected, I doubt it even took 1/3 rudder to counteract, but it was interesting.

I'm wondering if there are any insights as to why one would fail, and what maintenance can be done to it or preventative actions taken. I'm assuming that the very cold weather being here now has something to do with it. No moisture prior to that (and I'm in a very well-sealed hangar, though it's unheated).

Anything that can be done short of pulling 'em out of the wings and sending 'em back to Precise Flight? FWIW, these are the factory-installed ones on the Mooney Ovation. Also, after landing I tried again and a couple tries later, they worked. Haven't tried since.

Thanks!
Click to expand...

had that happen once. ice in one mechanism was our guess. you need to test again IN FLIGHT where the unit is under load and see if you still have a problem.

Sent from my Nexus 7 using Tapatalk 4
 
TMetzinger said:
had that happen once. ice in one mechanism was our guess. you need to test again IN FLIGHT where the unit is under load and see if you still have a problem.
Click to expand...

That was my guess too, but I'm not sure where the moisture would have come from to form the ice.

I'm guessing that after a trip into the (heated) shop, they'll be fine. I think they're just going to squirt some sort of lube in there anyway, and we'll see what happens.
 
Now that I'm not on my phone.... There ARE adjustments that can be made by a shop that don't require a replacement from PreciseFlight. But if the speedbrakes consistently misbehave, replacement is the typical cure - there are various switches/sensors inside the assembly and they're not really field-replaceable.

Later in the year, we ended up replacing the same brake in the Mooney as it started "flapping" (out/in/out/in) on extension.
 
We had occasional trouble with ours too. The older ones had a drain hole on one side and on the Comanche it was not the low side so it collected water which froze at altitude. The first time we sent them back and precise flight overhauled them and fixed them. (think it was free). I think for the last 10 years or so they're made without that issue. We've had a motor burn out too. Speed Brakes are nice on slippery planes.
 
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