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Mooney Bravo m20m 1998 

My speed brakes were working perfectly up until today

In fact, they worked perfectly on the ground during the run-up!!

However, during my flight today I had them extended as I was slowing to the speed for the approach.

But as I hit the button to retract them only one went down. The other did not

I had to land with one extended

That was really not an issue at slow speed.

But now I cannot use them now as only one deploys.

When I got to the main ramp I tried to pull the breaker and the one that was stuck dropped into the wing

Now I cannot get the troublesome one to extend.

Something is wrong.

By the way, it was about -5c when this occurred 

I looked at other threads here re: speedbrakes and my vacuum system is in the green

Thoughts, anything I can fix myself or ideas on troubleshooting further

Peter

 

 

 

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Your SB's will be electric, there are a number of micro switches in the cartridge, but precise flight suggests that they be IRAN'd every 1000 hours.   

To start you want the electrical diagram for your model (PM me if you don't already have that). 

If it isn't going up or down at all I would connect the other SB for  a ground test to see if it was the cartridge, or the controller/wiring.     I think you can also plug the cartridge directly into the controller bypassing the wing wiring to remove that from the equation. 

By design the SB's have a spring and the clutch mechanism holds them extended by electricity... so that if you pull the breaker it will always retract.   So you need power to extend them, you need power to keep them extended, and it uses power to retract.. but if you pull the breaker they will slam closed. 

I have a weird Asym issue with mine and will probably send them out for the 1000hour IRAN this annual.  I was able to fix a previous problem by adjusting a microswitch, but the asymmetric deployment circuitry is more complex. 

 

 

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I recently had one speed brake that did not fully retract when commanded, but did when I turned off the master. Similar to your problem. Take both of them out and send them to Precise Flight. They are good people to deal with. Fixed on time, but mine cost $1350.

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What Paul M said.

I did one of mine last year...same issue...it worked until it didn't.  Sent it in for repair.  1 AMU IIRC.

Btw, mine is a 98 Bravo as well.  I think this is the third or fourth time for sending a speedbrake to Precise Flight.

Edited by carqwik

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6 minutes ago, carqwik said:

What Paul M said.

I did one of mine last year...same issue...it worked until it didn't.  Sent it in for repair.  1 AMU IIRC.

Btw, mine is a 98 Bravo as well.  I think this is the third or fourth time for sending a speedbrake to Precise Flight.

My plane is a 1982 K model with the speed brakes installed a few years later (my plane in in for an annual, so I don't know the exact year.)

My maintenance records do not show any speed brake work until a few months ago.

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2 hours ago, PaulM said:

Your SB's will be electric, there are a number of micro switches in the cartridge, but precise flight suggests that they be IRAN'd every 1000 hours.   

To start you want the electrical diagram for your model (PM me if you don't already have that). 

If it isn't going up or down at all I would connect the other SB for  a ground test to see if it was the cartridge, or the controller/wiring.     I think you can also plug the cartridge directly into the controller bypassing the wing wiring to remove that from the equation. 

By design the SB's have a spring and the clutch mechanism holds them extended by electricity... so that if you pull the breaker it will always retract.   So you need power to extend them, you need power to keep them extended, and it uses power to retract.. but if you pull the breaker they will slam closed. 

I have a weird Asym issue with mine and will probably send them out for the 1000hour IRAN this annual.  I was able to fix a previous problem by adjusting a microswitch, but the asymmetric deployment circuitry is more complex. 

 

 

NIcely said. I have an intermittent issue with my pilot side SB, with the old microswitches. This has been ongoing throughout the planes history. It is excerbated at lower bus voltage so suspect it is one of the microswitches. I drown them in contact cleaner once in a while and it seems to keep hanging in there. If not, I just pull the breaker and it seems to come back to normal. It is part of the pre-flight to make sure they work, and know that I can expect them to be there.

I have also come to be able to fly with only one out. A bit of a yaw, but entirely manageable.

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I've had the same problem with one speed brake retracting and one not. Slowing to approach speed and  popping the breaker saved me when I was stuck and I had to divert to an alternate. I recently got a quote for $1,500 from precise flight to service the cartridges on my m20k.

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It could be a simple $10 issue, if the speed brakes are like mine.  I'm not sure when precise flight changed their speed brakes.  I have a 1991 Bravo and there is a spring that handles the retract.  They break every year or two.  I bought 4 of them from Precise Flight and proactively change them yearly at Annual.  It's a ½ hour job for each one, as each speed brake needs to be removed.

 

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6 hours ago, donkaye said:

It could be a simple $10 issue, if the speed brakes are like mine.  I'm not sure when precise flight changed their speed brakes.  I have a 1991 Bravo and there is a spring that handles the retract.  They break every year or two.  I bought 4 of them from Precise Flight and proactively change them yearly at Annual.  It's a ½ hour job for each one, as each speed brake needs to be removed.

 

Hi Don... My Mooney is a 1998 m20m

I can see a spring in the wing and it seems to be intact.

I have a feeling this is going to cost me some $$ and time, but we will check out the spring fix

That would be awesome if it was 10 bucks!

Thank you

Pete

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Seems ridiculous $1000+ for overhaul every 1000 hours for a part that maybe gets 20 hours of actually working?  

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16 minutes ago, Mark89114 said:

Seems ridiculous $1000+ for overhaul every 1000 hours for a part that maybe gets 20 hours of actually working?  

Welcome to certified AC.

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1 hour ago, HRM said:

Welcome to certified AC.

I know, I know.  I have been around airplanes for 25 years.  I just like to bitch about the lunacy of it.  Don't expect anything to change or get better.  

 

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Ok,  I'll bite!!!  what could cost 1000.00 to replace on a SB assembly?  Even if they charge 250.00hr min. 2hr what could even cost 500.00?  I wonder if moisture is getting in and freezing.

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1 hour ago, Dream to fly said:

Ok,  I'll bite!!!  what could cost 1000.00 to replace on a SB assembly?  Even if they charge 250.00hr min. 2hr what could even cost 500.00?  I wonder if moisture is getting in and freezing.

Mine (2000 series electric, installed in 2001) had less than 600 hours TTIS.

I was quoted 3361 USD (!!!) to overhaul them last month. I ended with a standard exchange for 3200 USD. Needless to say that I spent more $$$ than expected...

Edited by Guillaume

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6 minutes ago, larryb said:

Does anybody have a maintenance manual for these?

I don't think there is one. I have the installation manual for the 2000 series and it just says :

4.4 MAINTENANCE INSTRUCTIONS
Maintain aircraft structure, and wiring in accordance with aircraft maintenance manual, and FAA AC 43.13.

INSTRUCTIONS FOR CONTINUED AIRWORTHINESS are listed in the install manual

Edited by Guillaume

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5 hours ago, Mark89114 said:

Seems ridiculous $1000+ for overhaul every 1000 hours for a part that maybe gets 20 hours of actually working?  

Probably not any more ridiculous than $1,000 I just paid for an exhaust clamp.  The clamp is required to be replaced if the bolt holding it on is unscrewed twice.

Speed Brakes are so useful that it's "close your eyes" and pay the price.

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This may sound crazy, but check to make sure all of the screws are there and secure that around the opening of the brakes.  I had very similar issue to you and evidently a couple of screws had backed out causing just enough of an ability for the brake frame to flex in flight.  This caused the brake with the missing screws to bind enough to prevent full retraction.  

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I had a SB issue once caused by carelessness on my part, I always assist with the annual inspection and was checking the strobes, nav and all outside lights. Instead of going around to get in and out of the plane I opened the pilots side vent window so I could reach in and turn the lights on and off and get at the master switch. Well........the mechanic always puts a clean blanket on the wings so I don't get any scratches while its setting in the hangar. That's all fine and good until I reach in the vent window to kill the master and inadvertently hit the SB button on the yoke while the blanket was laying on the wing, and yes on top of the SB. The problem was I retracted the brakes before moving the blankets off the extended SB. when I retracted one of the SB's bound on a piece of blanket and then one side wouldn't fully retract. The mechanic removed the offending SB and cleaned it, after it was reinstalled they seem to work fine and retract fully, so hopefully when the annual is finished they work fine in the air as they do on the ground. Moral of the story, don't lay ANYTHNG on the wing near the SB's and turn the master switch on unless you pull the SB breaker so there is no inadvertent operation of the SB's.

Edited by triple8s
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I looked at the wiring diagram for the 1998 era, and the cartridge is fairly simple.. motor, 2 microswitches 1 clutch. 

So, do the field test with the other cartridge to confirm it is in the unit and not controller/wiring...   

then you can open the cartridge and check that the microswitches activate at the 2 positions (closed and open) 

This thread had the cam adjustment documents in it:

https://mooneyspace.com/topic/18990-precise-speed-brakes-sensor/

The one in my Bravo (2005) has greater complexity in the asym detection.. and a different limit sensor system.

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11 hours ago, donkaye said:

Probably not any more ridiculous than $1,000 I just paid for an exhaust clamp.  The clamp is required to be replaced if the bolt holding it on is unscrewed twice.

Speed Brakes are so useful that it's "close your eyes" and pay the price.

There needs to be one place on this forum that is devoted saving each other money. 

The exhaust V-Band clamp part number that Don refers to is Lycoming 40D23255-340M which sells for $1060 (http://www.aircraftspruce.com/catalog/eppages/lycomingcouplings.php) .

However the Mooney service bulletin (http://mooney.free.fr/Mooney SB SI/283a.pdfsays that the equivalent Aeroquip part number NH1009399-10 can be used. Aeroquip makes the above part for Lycoming - they are the exact same part (see picture below). Lycoming names them as their vendor on this part on this service instruction: https://www.lycoming.com/sites/default/files/Assembly and Torque Procedures for V-Band Couplings.pdf).

The Aeroquip part is $539 at Aircraft Spruce (http://www.aircraftspruce.com/catalog/eppages/engineclamps.php). LASAR has it for $544 (https://lasar.com/product/turbo-v-band-clamp-nh1009399-10/)

 

5a851cc9855f9_Vbandturboclamp.jpg.13d3a021831d6577aaf27a763bb29215.jpg

Some shops are buying the Aeroquip clamp and selling it for the Lycoming price. 

$500 here and $500 there adds up.

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In 2005 they charged only $192.59 to go through and repair as necessary one 100 series speed brake on a 1993 M20M. Now I'm sure it's a lot more. It would be good if we posted copies of invoices to compare what we are getting charged.

5a8522c832cd6_speedbrakerepair2005.thumb.png.d919c7f735d9ee2ea893e4a7700ff9f0.png

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I sent mine in for OH when it stopped working...

Clutches wear out...

Sure it would be nice if it wasn’t...

  • a mystery how to get the cartridge out.
  • clutches didn’t wear out so quickly.
  • cost more time than money for the round trip to the OH...

Best regards,

-a-

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