Electric Speedbrake Longevity

[PT20J]

I have factory installed electric speedbrakes on my 1994 M20J. I rarely use them and keep them lubricated per the Preciseflight ICA. I’m the third owner and the airplane only has about 1250 hours on it. From the logbooks, each previous owner sent the cartridges back to Preciseflight for repair (once each). The airplane has always been hangared.

Yesterday, the right brake failed to deploy. I called Preciseflight and was told that it is probably the motor and that they will repair it for a cost of $1700 to $2900 depending on what is required to fix it. 

So, it seems as though mine fail every few years and are rather expensive to repair. I’m curious what experience others have had.

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[ArtVandelay]

I’ve had my J for 7 years and it’s always hangared at home but does stay out when I travel. I had to have mine removed and readjusted/lubed once when they would not fully retract. They’ve started doing it again. I try to use them once a month just to exercise them. Try them on the ground without the engine running, does it sound like the motors are running.

[Davidv]

17 minutes ago, PT20J said:

I have factory installed electric speedbrakes on my 1994 M20J. I rarely use them and keep them lubricated per the Preciseflight ICA. I’m the third owner and the airplane only has about 1250 hours on it. From the logbooks, each previous owner sent the cartridges back to Preciseflight for repair (once each). The airplane has always been hangared.

Yesterday, the right brake failed to deploy. I called Preciseflight and was told that it is probably the motor and that they will repair it for a cost of $1700 to $2900 depending on what is required to fix it. 

So, it seems as though mine fail every few years and are rather expensive to repair. I’m curious what experience others have had.

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Mine were installed at the factory in 1992 and after I bought the plane in 2019 the right one failed. I sent them to Precise flight and they said it was the first time they had seen them since 1992.  I had them both overhauled for $1900 and have worked fine for the last 400 hrs (fingers crossed).

[PT20J]

3 minutes ago, ArtVandelay said:

I’ve had my J for 7 years and it’s always hangared at home but does stay out when I travel. I had to have mine removed and readjusted/lubed once when they would not fully retract. They’ve started doing it again. I try to use them once a month just to exercise them. Try them on the ground without the engine running, does it sound like the motors are running.

No, it’s just dead. 

[Davidv]

As I'm sure many have experienced, a good way to scare anyone else in your hangar is to turn the master off with the breaks still deployed.  I think everyone has done this once and never again  

[ArtVandelay]

No, it’s just dead. 

I would get out the multimeter and check if you have a switch or wiring issue before going through the overhaul process.

[RJBrown]

34 minutes ago, ArtVandelay said:

I would get out the multimeter and check if you have a switch or wiring issue before going through the overhaul process.

Easy to pull and access everything. Check it first before throwing money at it.

[201Mooniac]

I bought my M20J in 1995 and it had Precise Flight speed brakes installed in 1992.  AFAIK, they have never been out of the airplane for any type of repair.  I used them frequently when I first bought the plane to make up for my lack of Mooney skills but in the last 20 years or so they are used maybe once a month.

I did have to replace the LED on the panel twice though as it seemed to die and I didn't have the deploy annunciation.

[irishpilot]

Don't be scared to remove and inspect it. They are way past their warranty period. Precise will always tell you to send them in. My right speedbrake would't fully retract. My A&P and I removed and inspected. $36 dollar spring later, we were back in business. 

If yours isn't moving at all, listen to hear if the gears are engaging. If not, check via voltmeter. If good voltage, then remove and inspect. 

 

[carusoam]

Usual issue with the electric speed brakes is the wearing of the clutches... followed by failure to deploy...

Mine get exercised during pre-flight...

I have sent them both in for OH after 20years and 1500 hours...

Best regards,

-a-

[Mark89114]

These are one of the most poorly engineered, overly complex pieces of equipment I have ever seen, slight exaggeration maybe.  When I bought my ovation they had just been "overhauled" at the above prices and they quit working several months later.  Pricing was as above, so the hangar fairies took them apart and cleaned and made adjustments and they worked again for another 3 years.  Problems continued occasionally.  Don't understand what they could have done to them during the previous overhaul that was worth $1800.  For an item that is used 2 minutes for every 2 hours of flying, the reliability is crap.  Almost as bad as the stall warning switches we have installed.  Surely they could make something that lasts.  Rant over.    

[larryb]

Just for fun I built myself a speed brake bench test circuit. Two switches in small enclosure and a connector that matches the aircraft. I figured I should build it before the break so I can do some preliminary testing. I used the Mooney schematic and verified with a voltmeter to come up with the design. Unfortunately I have yet to test the device since the plane is in the shop for annual. 

[PT20J]

6 hours ago, Mark89114 said:

These are one of the most poorly engineered, overly complex pieces of equipment I have ever seen, slight exaggeration maybe.  When I bought my ovation they had just been "overhauled" at the above prices and they quit working several months later.  Pricing was as above, so the hangar fairies took them apart and cleaned and made adjustments and they worked again for another 3 years.  Problems continued occasionally.  Don't understand what they could have done to them during the previous overhaul that was worth $1800.  For an item that is used 2 minutes for every 2 hours of flying, the reliability is crap.  Almost as bad as the stall warning switches we have installed.  Surely they could make something that lasts.  Rant over.    

I have a similar opinion. The repair prices are kind of crazy given that these are pretty simple mechanical devices with minimal parts. Precise flight tech support told me the two most common failures are a micro switch (that’s presumably the $1700 repair) and the motor which gets water in it sometimes. Really? A device that is unsealed and completely open to the elements has a motor that fails when it gets wet. 

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[ArtVandelay]

I have a similar opinion. The repair prices are kind of crazy given that these are pretty simple mechanical devices with minimal parts. Precise flight tech support told me the two most common failures are a micro switch (that’s presumably the $1700 repair) and the motor which gets water in it sometimes. Really? A device that is unsealed and completely open to the elements has a motor that fails when it gets wet. 
Skip

If parking outside it might be prudent to use some painters tape to cover the brakes slots. Ounce of prevention...

[sgrooves]

My pilot side speedbrake failed. Multimeter shows power is coming from the plane. Not a single sound near the speedbrake so I’m guessing its probably something I can’t fix myself. It did happen when I had the plane parked outside in a bit of rain (normally hangared). Going to send off to PreciseFlight. Is this something that I can remove and re-install myself? Or do I need an A&P? 

 

[PT20J]

I pulled them both and connected the failed right one to the connector for the left and it would not deploy. The circa 1994 series 100 speed brakes do not have an interlock as later models to prevent only one from deploying. I sent it to Preciseflight for repair. They replaced every electrical and moving part. $1188.25. They don’t repaint them so it still looks old. 

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[sgrooves]

Just now, PT20J said:

I pulled them both and connected the failed right one to the connector for the left and it would not deploy. The circa 1994 series 100 speed brakes do not have an interlock as later models to prevent only one from deploying. I sent it to Preciseflight for repair. They replaced every electrical and moving part. $1188.25. They don’t repaint them so it still looks old. 

Skip

Thanks for that. Feels like that’s going to be my route here. Mine was installed in 1992 according to the logs. 

[MikeOH]

I've owned my plane for 4 years and the speed-brakes were installed 5 years before that.  I rarely use them in flight (maybe one out of ten flights when ATC slam-dunks me!), but exercise them as part of every pre-flight control check.  Never had a problem.  Whoever did the install sheet metal work is amazing; it's flawless.  I wonder if a poor/mis-aligned install could put stress/binding on the internals?

[PT20J]

1 hour ago, MikeOH said:

I've owned my plane for 4 years and the speed-brakes were installed 5 years before that.  I rarely use them in flight (maybe one out of ten flights when ATC slam-dunks me!), but exercise them as part of every pre-flight control check.  Never had a problem.  Whoever did the install sheet metal work is amazing; it's flawless.  I wonder if a poor/mis-aligned install could put stress/binding on the internals?

I don’t think so. All the moving parts are within a rigid frame. I think the problem is that all the parts are exposed to the weather. Even hangared planes usually end up outside sometimes. That’s why they say to grease the gears annually — water can wash out the grease since the gears are exposed. Preciseflight told me that they usually stop working because water gets into the motor or microswitches.

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[carusoam]

The usual clutch wear on the 94 models… leads to the blades not fully deploying or retracting…

Not sure what tells the motor to stop… probably has a timer…

Mine went in for service after 1600 hours… tested during pre-flight, hardly used in anger… 

Were they working perfectly, then just stopped working?

Best regards,

-a-

[carusoam]

Check the experience of another MSer today… 

lubricating worm gears may be in order…

-a-

 

[MatthiasArnold]

I had similar "electrical" problems with my Ovation's speed brakes.
Servicing them in accordance with the service manual is no rocket science.
Use plenty contact cleaner for the micro-switches and the connectors's plugs. Engage the switches multiple times during cleaning.
For more details refer to this post on MS.

Best,

Matthias

[Niko182]

On 5/4/2021 at 6:39 PM, irishpilot said:

Don't be scared to remove and inspect it. They are way past their warranty period. Precise will always tell you to send them in. My right speedbrake would't fully retract. My A&P and I removed and inspected. $36 dollar spring later, we were back in business. 

If yours isn't moving at all, listen to hear if the gears are engaging. If not, check via voltmeter. If good voltage, then remove and inspect. 

 

I was gonna say, I've seen people here say that a lot of the times, you can repair them yourself. not exactly a "complex mechanism". Precise flight charges a shit ton to be fair. I love my speed brakes and I think they're worth it, but I had to send them in 2 times in 2 years, and both times they charged right around 2k. Not exactly pocket money.

[PT20J]

I know a lot of folks recommend spraying stuff into switches, but as a EE let me point out that if it fixes anything, it is likely to be a temporary solution. Switch contacts are plated with a precious metal to lower resistance and prevent oxidation. They are designed to make contact with a wiping action to clean them. Eventually the thin plating wears through exposing base metal that will oxidize. When this happens, contact cleaner may remove the oxidation, but it will come back eventually. I only use it to confirm that the problem is the switch, and then I replace the switch.

Cleaner may be useful to free up a micro switch that is exposed to grease and grime and gets crud into the mechanism that prevents it from actuating. It may also just wash the crud into the contact area if the switch isn’t sealed.

And, don’t ever use regular WD-40 since it contains a light oil which will attract grime and also muck up the contacts.

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[Will.iam]

22 hours ago, carusoam said:

Check the experience of another MSer today… 

lubricating worm gears may be in order…

-a-

 

Also here is the post from when I was asking how and what to clean on the speed brakes and I included pictures.