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speed brakes


Duane Baker

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Mechanical?

vacuum driven?

Electric?

Or the kind that hinge up?


Sorry, I guessed... and assumed electric...

People that are really in tune with their Mooney would have stated what is powering them...

People that are less in tune, have moved up and now have electric everything...  :)


Just trying to be helpful... in a quirky PP kinda way...

Best regards,

-a-

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16 hours ago, carusoam said:

They have clutches that wear...

have mechanic remove and send out to... manufacturer.

https://www.preciseflight.com/general-aviation/shop/speedbrakes/

Quick, not so expensive... happens every other decade or so.

Best regards,

-a-

Generally I agree with everything you say!!!  However I take exception to "not so expensive".....I think it is running about $1000 for "overhaul", which I think I think is sinfully outrageous for a mechanism that gets used a total of maybe 10 hours in use before recommended OH or outright failure.  Rant over.  Maybe.

 

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2 hours ago, Mark89114 said:

Generally I agree with everything you say!!!  However I take exception to "not so expensive".....I think it is running about $1000 for "overhaul", which I think I think is sinfully outrageous for a mechanism that gets used a total of maybe 10 hours in use before recommended OH or outright failure.  Rant over.  Maybe.

 

Sorry Mark...

I must have forgotten what I paid to get that done...

They were pulled, sent out, and back within days...?

Lately I have been caught with old pricing data too... there has been some inflation as well over the years...

Sorry, my bad...

I remember calculating total time of use...

Similar to landing gear... a few seconds each flight...

Speed Brakes shouldn’t wear at all... they aren’t under any great force like the landing gear...

PP thoughts only, not a mechanic...

Best regards,

-a-

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Speed brakes are supposed to be lubricated every year. I would bet that a lot of failures are units that are never lubricated and run until failure. My MSC does not service them automatically during annual unless asked by the owner. They don’t even suggest it.

 

Perhaps the economics favor this. 1 hour labor per year for 15 years would $1875 in preventative maintenance.

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Before you take them out consider doing the following:

1. With power OFF walk over to plane, and with fingers gently extend guilty speedbrake to full extended position then let go and it will flop back down to retracted position.

2. Repeat several times.

3. Now turn on power and see if they extend.

I’m not promising anything, but I went through exact same issue with mine and after reading these forums came across this advice and tried it. It obviously worked. That was over a year ago. Let us know how it goes.

Dan


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  • 2 weeks later...
On 10/21/2019 at 7:52 PM, larryb said:

Speed brakes are supposed to be lubricated every year. I would bet that a lot of failures are units that are never lubricated and run until failure. My MSC does not service them automatically during annual unless asked by the owner. They don’t even suggest it.

 

Perhaps the economics favor this. 1 hour labor per year for 15 years would $1875 in preventative maintenance.

I just serviced mine this morning. Removing them is very easy (I have the electric type). I removed all of the top screws and then the bottom screws. Once the bottom inspection plate is off there are two small screws on a bracket that need to be removed. Then the electric plug needs to be unplugged and the entire unit will come out of the bottom.

My right speed brake is original and has never been serviced by Precise Flight. It was getting slow and very noisy. No wonder - there was no grease on the gear and worm drive. After generously applying Aeroshell 22 grease I put it on a stool under the airplane (with the master on and the speed brake switch on). Every time I plugged in the connection it would activate. After a few cycles it was noticeably quieter and faster to deploy. 

The left one was serviced almost 20 years ago and was doing well even though there was very little grease left. I re-greased it and went through a few cycles with both. The right one is now deploying just as fast as the left and both are considerably quieter. It took about 45 minutes total and was very easy.

I'll be doing it every year from this point on.

488402793_ScreenShot2019-11-06at12_12_01PM.thumb.png.31817c2b3c8bd1e9bd3ccb7cdcd22304.png

 

 

 

 

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The problem with the electric speed brakes is that the worm and mating gear are exposed to any water coming in through the top of the wing and the grease can wash out. It's not a bad idea to remove them for inspection, but if you don't want to take out the screws from the top (if for instance you've got new paint and don't want to mess with it), I found it possible to grease them in place from below with a long Q-tip when in the up position. Don't overdo it -- you don't want grease to find it's way into the clutch.

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  • 3 weeks later...

Update on F/B speed brake, it was the gears inside the motor, not gears on the outside that you can grease. My AP/IA found the motor on line $64. PF makes it hard to replace by deforming the set screw that holds the gear on the motor shaft, my god like AP got it off. Waiting for the motor to show up, will update when installed. Duane

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DO NOT DEPLOY SPEED BRAKES IN ICING CONDITIONS . They will get stuck in the extended position. Lubricate them with WD-40 yearly. The speed brakes switch is next to the PTT switch on the yoke making it prone to be depress by accident specially during icing conditions when you will be wearing gloves. Some of my friends had them removed for an extra 6 gallons of fuel in the long range tanks.

Edited by Gagarin
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3 minutes ago, Gagarin said:

DO NOT DEPLOY SPEED BRAKES IN ICING CONDITIONS . They will get stuck in the extended position. Lubricate them with WD-40 yearly. The speed brakes switch is next to the PTT switch on the yoke making it prone to be depress by accident specially during icing conditions when you will be wearing gloves. 

Good advise. I accidentally hit that yoke switch once in very light icing and immediately retracted them again. The left brake didn’t retract fully until I had descended below the freezing level. Pretty scary. 

I wouldn’t use WD-40 though. The manual warns not to use spray lubricants (I believe that’s because it can get into the clutch and cause slippage) and the solvents can wash the grease off the gears. 

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To prevent accidental speed brakes deployment just pull the brakes CB out. Or relocate the speed brakes switch to the panel or the opposite arm on the yoke. BTW I found the flaps to be more effective for a steep descend than the brakes. I found the VSR very effective for planning the descent than trying to correct a botched descent.

Edited by Gagarin
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5 hours ago, PT20J said:

I wouldn’t use WD-40 though. The manual warns not to use spray lubricants (I believe that’s because it can get into the clutch and cause slippage) and the solvents can wash the grease off the gears. 

Good advice, the Aeroshell 22 specified is a pretty heavy grease and seems to hold up very well to the harsh, wet environment they are in.

( :) Of course WD-40 is good for all other things . . . pre-flight de-ice, urinary tract infections caused by relief tubes over the North Atlantic, etc, etc. :) )

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To prevent accidental speed brakes deployment just pull the brakes CB out. Or relocate the speed brakes switch to the panel or the opposite arm on the yoke. BTW I found the flaps to be more effective for a steep descend than the brakes.

I moved the switch, the other bad thing about the normal position is you can’t see it, so you hit it accidentally and can’t see it’s lighted. I know, you can look out the window, but this happened to me on a missed approach in real IMC...after that I was motivated to fix the problem.


Tom
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  • 5 weeks later...

The rest of the story, there are two cams with micro switches that control the power and witch way they go. One of the cams came loose and moved, this let the geared motor keep running and destroyed the gear inside the motor. Lubing the external gears would not have helped avoid this. My AP/IA found the motor $64, retimed the cams and we are back to normal and they work fine. After getting inside the speed brake and seeing how they work I'm going to start covering them when I wash the plane to help protect them and a little corrosion-X to lube them up.

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1 hour ago, Duane Baker said:

The rest of the story, there are two cams with micro switches that control the power and witch way they go. One of the cams came loose and moved, this let the geared motor keep running and destroyed the gear inside the motor. Lubing the external gears would not have helped avoid this. My AP/IA found the motor $64, retimed the cams and we are back to normal and they work fine. After getting inside the speed brake and seeing how they work I'm going to start covering them when I wash the plane to help protect them and a little corrosion-X to lube them up.

Precise Flight's instructions say specifically not to use spray lube, only Aeroshell 22.

292906775_ScreenShot2019-12-25at10_53_06AM.thumb.png.6244e97b24c9d38e6a47a7a2be37ac04.png

 

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