Speed Brake Overhaul

[A64Pilot]

22 minutes ago, ilovecornfields said:

Interesting. I just looked at the Precise Flight website to try to get the document @Debposted and saw that they advertise them as being good in turbulence. Has anyone tired this? I usually just slow to maneuvering speed and put the gear down if it’s really bad but I’ve never tried using speed brakes.

I don’t see any reason why they wouldn’t, they provide drag and slow you down, but at least as important this extra drag helps keep you from over speeding.

It’s been a long time since I flew with them, but I don’t remember a max speed limit?

[Fly Boomer]

1 minute ago, A64Pilot said:

It’s been a long time since I flew with them, but I don’t remember a max speed limit?

Vne

[A64Pilot]

4 minutes ago, Fly Boomer said:

Vne

Understood, but that’s aircraft, gear and flaps of course have their own, much lower limits. I try to avoid turbulence, but the few times I’ve not been able to one of the biggest challenges has been speed control, so much so I’ve asked Center for a block altitude and controlled excess speed by bleeding it off in a climb.

Speed brakes don’t reduce max airspeed like say flaps or gear would. So I would think using them in turbulence would be a very logical thing to do.

[Fly Boomer]

2 minutes ago, A64Pilot said:

Speed brakes don’t reduce max airspeed like say flaps or gear would. 

Speed brakes at any speed, then gear when slow enough, then flaps when slow enough.  Might be able to avoid big climb.

[kortopates]

30 minutes ago, ilovecornfields said:

Interesting. I just looked at the Precise Flight website to try to get the document @Debposted and saw that they advertise them as being good in turbulence. Has anyone tired this? I usually just slow to maneuvering speed and put the gear down if it’s really bad but I’ve never tried using speed brakes.

I've used mine several times encountering severe turbulence along the Owens Valley. They're helpful to get slowed down below gear speed so that the gear can then be deployed, which aids in stability, to ride it out at Va. 

[larryb]

I lube mine every year and only run them when needed. Seems like a lot of extra wear to run them every pre-flight. I use them regularly enough in flight.

[glenn reynolds]

I absolutely use the speed brakes to slow the plane in turbulence. It’s fast 

[N6936V]

Hi Y'all!

Precise Flight repaired my right-side speed brake in 2017 for $1050 + S&H.  Now the left-side needs to be fixed. 

Their new policy: "we only repair both at the same time, $2000 + S&H!!!  I argued that the right-side works ok; their reply $2000!!  So I'm stuck paying $3000 over a 5-year period for speed brakes.  What happened to customer service in our industry?

BTW: I've been flying with the breaker pulled for the past months and don't miss the speed brakes at all. 

Blue side up!

[ArtVandelay]

Hi Y'all!
Precise Flight repaired my right-side speed brake in 2017 for $1050 + S&H.  Now the left-side needs to be fixed. 
Their new policy: "we only repair both at the same time, $2000 + S&H!!!  I argued that the right-side works ok; their reply $2000!!  So I'm stuck paying $3000 over a 5-year period for speed brakes.  What happened to customer service in our industry?
BTW: I've been flying with the breaker pulled for the past months and don't miss the speed brakes at all. 
Blue side up!

Yep, from now I’m going to tape over the brakes to protect them from rain.
Ounce of prevention…

I missed mine, no slam dunks.

[Will.iam]

19 hours ago, N6936V said:

Hi Y'all!

Precise Flight repaired my right-side speed brake in 2017 for $1050 + S&H.  Now the left-side needs to be fixed. 

Their new policy: "we only repair both at the same time, $2000 + S&H!!!  I argued that the right-side works ok; their reply $2000!!  So I'm stuck paying $3000 over a 5-year period for speed brakes.  What happened to customer service in our industry?

BTW: I've been flying with the breaker pulled for the past months and don't miss the speed brakes at all. 

Blue side up!

If you are mechanically inclined it might be worth your time to take them out and clean and lube the worm gear with aeroshell 22 grease. I had one that failed which would cause the other one to automatically fall be down once it detected the other side didn’t deploy. I cleaned greased the failed one and low and behold it worked fine! It was so easy to do i did the other side as a preventative measure. And now do it each annual as that is a common item that gets missed at annual. 2.5 years and still working great. 

Edited May 27, 2023 by Will.iam

[PT20J]

$2000 bucks is a lot for something I hardly ever use in my M20J. The design isn't great because they are open to water from above and Precise Flight admitted that the motor and switches are not hermetically sealed and get water in them and that's usually what causes them to stop working. I think that's why they replace everything electrical during an overhaul. Their policy is probably based on the theory that if one got wet, the other probably is going to fail soon, too.

They are supposed to be lubed annually because it's also possible to for the grease to wash out. I think @Will.iam meant Aeroshell 22. I found that it is possible to lube them from the top using a stir stick by lifting the  brakes to gain  access. I have the older 100 series, but it probably is possible to do that with the newer ones though I haven't tried it. I don't like to take them out because the frame isn't that thick and only has 2-3 threads for the screws to grab and several of mine stripped out from removing and reinstalling and I had to drill and tap them for larger screws.

Skip

 

[Will.iam]

10 hours ago, PT20J said:

$2000 bucks is a lot for something I hardly ever use in my M20J. The design isn't great because they are open to water from above and Precise Flight admitted that the motor and switches are not hermetically sealed and get water in them and that's usually what causes them to stop working. I think that's why they replace everything electrical during an overhaul. Their policy is probably based on the theory that if one got wet, the other probably is going to fail soon, too.

They are supposed to be lubed annually because it's also possible to for the grease to wash out. I think @Will.iam meant Aeroshell 22. I found that it is possible to lube them from the top using a stir stick by lifting the  brakes to gain  access. I have the older 100 series, but it probably is possible to do that with the newer ones though I haven't tried it. I don't like to take them out because the frame isn't that thick and only has 2-3 threads for the screws to grab and several of mine stripped out from removing and reinstalling and I had to drill and tap them for larger screws.

Skip

 

Yes. Aeroshell 22 my bad i corrected the original post thanks. 

[Fly Boomer]

15 hours ago, Will.iam said:

If you are mechanically inclined it might be worth your time to take them out and clean and lube the worm gear with aeroshell 22 grease. I had one that failed which would cause the other one to automatically fall be down once it detected the other side didn’t deploy. I cleaned greased the failed one and low and behold it worked fine! It was so easy to do i did the other side as a preventative measure. And now do it each annual as that is a common item that gets missed at annual. 2.5 years and still working great. 

Looks like yours is a 1986.  Mine is 1989, but still has vacuum speed brakes.  Have yours been replaced, or are they vacuum as well?  If vacuum, do you have any documentation on how to service them?

[jetdriven]

they stopped support for the vacuum brakes. They want you to buy electric ones for 8K and then spend a few grand installing them.

[Fly Boomer]

18 minutes ago, jetdriven said:

they stopped support for the vacuum brakes. They want you to buy electric ones for 8K and then spend a few grand installing them.

I'm not there yet.  Any documentation on servicing the vacuum brakes?

[Rick Junkin]

13 minutes ago, Fly Boomer said:

I'm not there yet.  Any documentation on servicing the vacuum brakes?

I found this document when I was looking for info on the vacuum brakes a number of years ago. Not a maintenance document, and it's for the installation on a J, but shows where all of the brake pivot points are.

Cheers,
Rick

M20J Vacuum Speedbrake Install Manual.pdf

[Fly Boomer]

9 minutes ago, Rick Junkin said:

I found this document when I was looking for info on the vacuum brakes a number of years ago. Not a maintenance document, and it's for the installation on a J, but shows where all of the brake pivot points are.

Cheers,
Rick

M20J Vacuum Speedbrake Install Manual.pdf 4.18 MB · 0 downloads

That will be handy.  Thank you!

[Will.iam]

On 5/27/2023 at 12:17 PM, Fly Boomer said:

Looks like yours is a 1986.  Mine is 1989, but still has vacuum speed brakes.  Have yours been replaced, or are they vacuum as well?  If vacuum, do you have any documentation on how to service them?

Sorry although my 252 came out of the factory with vacuum speed brakes there were replaced with electric ones by a previous owner. 

[Fly Boomer]

5 hours ago, Will.iam said:

Sorry although my 252 came out of the factory with vacuum speed brakes there were replaced with electric ones by a previous owner. 

I wish mine had.

[Pinecone]

Mine has been. 
A nice surprise after I purchased as it was not mentioned presale

[M20F-1968]

On 10/21/2022 at 11:32 AM, ilovecornfields said:

Interesting. I just looked at the Precise Flight website to try to get the document @Debposted and saw that they advertise them as being good in turbulence. Has anyone tired this? I usually just slow to maneuvering speed and put the gear down if it’s really bad but I’ve never tried using speed brakes.

It was recommended to me by a high-time Mooney pilot that he uses speed brakes regularly on landings, particularly cross-wind landings.  I have tried that several times and found that the landings with speed brakes have been some of my best landings.  By design, you are forced to carry more power for the same airspeed.  The plane feels heavier and seems more stable.  Any thoughts, positive or negative?

John Breda

[exM20K]

12 hours ago, M20F-1968 said:

It was recommended to me by a high-time Mooney pilot that he uses speed brakes regularly on landings, particularly cross-wind landings.  I have tried that several times and found that the landings with speed brakes have been some of my best landings.  By design, you are forced to carry more power for the same airspeed.  The plane feels heavier and seems more stable.  Any thoughts, positive or negative?

John Breda

Chris Koppel did a video in this.  He observed a 2 KIAS increase in landing configuration stall speed when using the speed brakes. I’d be careful here.  It may be that your landings are better with the speed brakes out because you are closer to stall speed.  I don’t use them in before touchdown but do on the rollout at my short home field.  They probably don’t do much, but at least I don’t look as ridiculous as my neighbor who holds open the door on his Cirrus.

1.2 - 1.3 x Vso works very well for me. I have confirmed stall warning and stall speed for various weights and configurations.

 

-dan