Speedbrake does not fully retract

[Fritz Kaiser]

Hi folks,

at my last flight in my '95 O1  the RH speedbrake does not fully retract.

the speedbrake is aprox. 1cm out of its house .

I recycled the brake three times... always the same result.

After shut down the engine and switching the masterswitch off, the speedbrake disappeared correctly in the wing.

I attempted a new test, if electric power is on the malfunction is still present. electric power of... speedbrake retract fully.

what is the problem?  any suggestions?

Thanks in advance

Fritz

 

 

[PT20J]

There's a logbook entry on my airplane from before I owned it that says this was fixed by adjusting a microswitch in the speed brake. 

Skip

[anthonydesmet]

Also, If you haven’t already give Precise Flight a call (I’m assuming that’s your SB type) and give then your a/c sn.  They will tell you the type series of SB installed if not in your logbook.  They will also point you towards the manufacture recommend service items.  Sometimes dirt and moisture can clog things up and you may need to pull the cartridges (not hard) clean and lube per the service recommendation.

I had same issue my first year of ownership but I pull every other annual now and have not had an issue.

[N131MA]

I had the same issue some time ago. If this happens inflight, pulling the circuit breaker will fully retract the speed brake again.

Precise Flight sent me calibration instructions for the microswitches. The process is no rocket science and the calibration takes an hour or so.

Fritz: If you PM me your email address I am happy to send the pdfs.

[carusoam]

Hey Fritz!

While you are at it... check how many hours you have on the speed brakes...

Hard to tell much about wear, from hours of use...  

My Speed brakes went in for service at around 1500hrs... for new clutches... they wear, and then don’t operate very well...

Probably not your immediate challenge, just something to be aware of...  

Best regards,

-a-

[Mooney217RN]

I've been having this exact problem in recent months.  Honestly, I think it's related to the winter time temperatures.  My MSC (Top Gun) states that it's likely the micro-switch.  they can't service my units, which require to be removed and sent into Precise Flight.  Once I am flying, they left brake generally retracts normally, but when I check them on pre-flight, it doesn't retract entirely.

[MatthiasArnold]

Hallo Fritz,

I experienced some problems with my electrically actuated Precise Flight speed brakes as well after I purchased my O2 last summer. PF is not to blame at all - obviously they never got serviced since the plane left the factory in Kerrville in 2006. 

You can find the service manual at the PF website. I inspected and serviced them in accordance with the manual. Clean, remove the old grease, apply fresh grease (Aeroshell 22 if I recall correctly), apply tons of „Kontaktspray“ to the microswitches (with speed brake flaps in different positions), test them. During the re install take care of the electrical connectors as well (clean and apply „Kontaktspray“). As stated in the service manual apply the suitable Loctite to the screws. Test after installing, make logbook entry.

Since servicing they work like a charm!

If you have trouble dismounting the speed brakes, gently push from the bottom of the wing..

Regards,

Matthias

Edited January 14, 2021 by MatthiasArnold

[LANCECASPER]

7 minutes ago, Mooney217RN said:

I've been having this exact problem in recent months.  Honestly, I think it's related to the winter time temperatures.  My MSC (Top Gun) states that it's likely the micro-switch.  they can't service my units, which require to be removed and sent into Precise Flight.  Once I am flying, they left brake generally retracts normally, but when I check them on pre-flight, it doesn't retract entirely.

What they should have probably told you is that they haven’t been servicing your units. Every year at annual according to the instructions for continued airworthiness they are supposed to remove the speed brake and use a specific Aeroshell grease on the gears (no spray lube!!). Before i knew this mine were slow to retract also and now without sending them in for service they operate fine.

[ZuluZulu]

11 minutes ago, LANCECASPER said:

What they should have probably told you is that they haven’t been servicing your units. Every year at annual according to the instructions for continued airworthiness they are supposed to remove the speed brake and use a specific Aeroshell grease on the gears (no spray lube!!). Before i knew this mine were slow to retract also and now without sending them in for service they operate fine.

This has been a very helpful thread.  I've been worried I would need to send mine in but there's a chance this will do the job.  I've been getting a transient, unpleasant yawing motion pulling the nose left because of asymmetric deployment.  The right wing is delaying a few seconds before popping out, while the left one immediately deploys.

[LANCECASPER]

5 hours ago, ZuluZulu said:

This has been a very helpful thread.  I've been worried I would need to send mine in but there's a chance this will do the job.  I've been getting a transient, unpleasant yawing motion pulling the nose left because of asymmetric deployment.  The right wing is delaying a few seconds before popping out, while the left one immediately deploys.

 

People make the mistake of spraying Tri-Flo which removes the Aeroshell 22 and there's no lube. Then once they fail they send them in for an overhaul.

Mine were a little noisy and one was a little slower than the other. I took the cartridge out, lubricated the worm and worm gear properly in each, and they both are much quieter and operate the same now. They should be lubed every year at annual. For airframes with TKS it might not be a bad idea to lube or at least inspect them twice a year.

 

[carusoam]

Great details gents!

Pics and procedures... wow.

thanks for sharing everything globally.

go MS!

Best regards,

-a-

[PT20J]

I found it possible to lube them without removing the cartridges. I just remove the access panels under the wings, raise the speed brakes and paint some AS 22 on the gear with an acid brush attached to the end of a dowel. 

They require yearly lube because they are not sealed and are open the weather.

Skip

[MatthiasArnold]

6 hours ago, PT20J said:

I found it possible to lube them without removing the cartridges. I just remove the access panels under the wings, raise the speed brakes and paint some AS 22 on the gear with an acid brush attached to the end of a dowel. 

They require yearly lube because they are not sealed and are open the weather.

Skip

Exactly - yearly servicing helps a lot

Depending on model and make of the speed-brakes. there are different ways to access & remove:

• Earlier models are direct accessible via the panels at the wings bottom (as described by Skip).
• The model installed at my 2006 O2 can only be accessed from the top:
  • Remove the 14 screws
  • By gently applying some pressure from the bottom of the wing the cartridges simply pop out at the top of the wing
  • Place them on a protective cover, and unplug (see image).
  • For servicing you have to remove the aluminum covers (as shown on the image provided in the previous post).
  • Like usual: installation in reversed order (applying Loctite to screws in accordance to the SM of course)

Matthias

 

[Lax291]

RH speed brake would not retract fully when I bought my plane about a year ago. Went to pull them today to clean up and lube with Aeroshell 22 to see if that would fix the retract issue...it did not. 

I couldn't even get the screws on top off as the heads started to strip (and my Kobalt brand philips screwdriver snapped!! P.O.S.) so I did everything from the access panel. Removed globs of grease that looks similar to vanilla frosting and then applied AS22 to the gears. 

I cycled a few times and still the RH brake did not retract fully.  

Just seeing if anyone had other thoughts on what else I could try just with access through the panel? 

[ArtVandelay]

RH speed brake would not retract fully when I bought my plane about a year ago. Went to pull them today to clean up and lube with Aeroshell 22 to see if that would fix the retract issue...it did not. 
I couldn't even get the screws on top off as the heads started to strip (and my Kobalt brand philips screwdriver snapped!! P.O.S.) so I did everything from the access panel. Removed globs of grease that looks similar to vanilla frosting and then applied AS22 to the gears. 
I cycled a few times and still the RH brake did not retract fully.  
Just seeing if anyone had other thoughts on what else I could try just with access through the panel? 

At least one of the screws on top looks rusted, I would change them all out if they’re binding.

When you pull power they’re supposed to snap down.

I would try gently moving the brakes and try to feel if there’s any binding, if not could be a problem with 1 of the limit switches.

[LANCECASPER]

1 hour ago, Lax291 said:

RH speed brake would not retract fully when I bought my plane about a year ago. Went to pull them today to clean up and lube with Aeroshell 22 to see if that would fix the retract issue...it did not. 

I couldn't even get the screws on top off as the heads started to strip (and my Kobalt brand philips screwdriver snapped!! P.O.S.) so I did everything from the access panel. Removed globs of grease that looks similar to vanilla frosting and then applied AS22 to the gears. 

I cycled a few times and still the RH brake did not retract fully.  

Just seeing if anyone had other thoughts on what else I could try just with access through the panel? 

Do whatever you have to do to get the cartridge all the way out if it's been years since they've been serviced. Hit each of the top screws with some Kroils to penetrate and loosen it up. Then after awhile, get a high quality, correct size, philips screwdriver and try the top screws by hand. The ones that don't come out you can carefully use an  EZ-out. (Those really don't look like the right screws . .  but maybe)

Once you get the cartridge out, then clean every bit of the old junk off of the worm and worm drive. You might need to use a swab and some alcohol to carefully clean just the worm and worm drive.  Then I would re-grease with Aeroshell 22 and plug them back in and exercise them a lot to see if you can get them to do what they should do. If all of that fails then, as a last resort, send that one in for rebuild. (Others have gone deeper into theirs' and revived them. I've never had to.)

[PT20J]

If they don't retract, there is some mechanical problem and you will need to remove them to figure out what's going on. The devices are very simple -- it will be obvious. If you need to send them to Precise Flight for repair, be ready for sticker shock. 

There seems to be two issues with lubricating these thing:. 1) they never get lubricated, or 2) they get lubricated using the theory that if a little grease is good, a lot must be better. When Precise Flight overhauled mine, they came back all cleaned up with a little dab of grease on the worm gear. It doesn't take much. Too much grease just makes a mess and attracts dirt.

[M20S Driver]

If you turn the power off and they retract fully, then it could also be the down micro-switch adjustment which can be done from the top (100 series).

[Lax291]

11 minutes ago, M20S Driver said:

If you turn the power off and they retract fully, then it could also be the down micro-switch adjustment which can be done from the top (100 series).

When I pull the breaker if the LH brake was up it would bang back down, but the RH would always stay out until I pushed it back in. 

[M20S Driver]

3 minutes ago, Lax291 said:

When I pull the breaker if the LH brake was up it would band back down, but the RH would always stay out until I pushed it back in. 

Does it freely move after you push it in?   If yes, it may be internal to the clutch.  If no, I would look at the rest of the assembly.

[Lax291]

It does move freely, both of them I can operate manually and pull out the brakes. 

[N201MKTurbo]

Mine did that once. It turned out to be the retract spring. It had broken where the screw hole was at the end of the spring. I used a Harbor Freight metal hole punch to make a new screw hole in the end of the spring and it has been fine ever since.

I tried to drill a new hole. Even with a carbide bit I couldn’t even make a scratch in the spring steel. The hole punch did the trick.

[Jetpilot86]

On 1/14/2021 at 1:47 PM, LANCECASPER said:

What they should have probably told you is that they haven’t been servicing your units. Every year at annual according to the instructions for continued airworthiness they are supposed to remove the speed brake and use a specific Aeroshell grease on the gears (no spray lube!!). Before i knew this mine were slow to retract also and now without sending them in for service they operate fine.

Regrettably, I don't think mine were getting serviced under the previous owner.  My left one wouldn't extend on the first flight after purchase and DMax told me the worm gear on that side is shot.  I get the 4 AMU fix as a result.

PSA:  Make sure they service the speed brakes!

[Rmnpilot]

Does anyone here have the repair manual for the 100 series electric speedbrakes?   I can probably figure out how to adjust the microswitches, but thought I would ask given the thread.  Thanks!

[Lax291]

54 minutes ago, Rmnpilot said:

Does anyone here have the repair manual for the 100 series electric speedbrakes?   I can probably figure out how to adjust the microswitches, but thought I would ask given the thread.  Thanks!

Would appreciate that as well, nothing I could find on the Google machine.