Speedbrakes Doing Their Own Thing

[TGreen]

Speedbrakes deployed on their own in flight today. Was able to retract the first time. Then they deployed again and would not retract until I landed and turned off the master. Turned the master back on and then they functioned normally. We had a lot of rain last week. Could that have been the cause?

[LANCECASPER]

2 hours ago, TGreen said:

Speedbrakes deployed on their own in flight today. Was able to retract the first time. Then they deployed again and would not retract until I landed and turned off the master. Turned the master back on and then they functioned normally. We had a lot of rain last week. Could that have been the cause?

Pull the breaker and they'll drop like a rock.

[StevenL757]

2 hours ago, TGreen said:

Speedbrakes deployed on their own in flight today. Was able to retract the first time. Then they deployed again and would not retract until I landed and turned off the master. Turned the master back on and then they functioned normally. We had a lot of rain last week. Could that have been the cause?

Personally, I’d double-check the wiring and security of the cannon plugs up inside the speed brake inspection panels on the bottom of the wing.  If they both look secure and all pins are seated properly, your issue is likely elsewhere in the electrical system.  I doubt you’d have two bad speed brakes.

[dkkim73]

What model are they? The newer ones have a central box that controls their deployment together. That could provide another source of failure or bad connection. Or the yoke switch if flaky. 

[LANCECASPER]

1 minute ago, dkkim73 said:

What model are they? The newer ones have a central box that controls their deployment together. That could provide another source of failure or bad connection. Or the yoke switch if flaky. 

My bet would be the yoke switch

[ArtVandelay]

What model are they? The newer ones have a central box that controls their deployment together. That could provide another source of failure or bad connection. Or the yoke switch if flaky. 

The older ones have a 4 way relay that acts as the control box, but I would check the switch first in this case.

[geoffb]

18 hours ago, LANCECASPER said:

My bet would be the yoke switch

agree, suspect you have a short to ground somewhere between the switch and the relay 

[PeterRus]

21 hours ago, dkkim73 said:

What model are they? The newer ones have a central box that controls their deployment together.

Judging by the M20R'06 (from the tail #) they are newer ones. 

[Coachella Bravo]

Recently, my speed breaks, would intermittently only deploy on one side.  Made for some interesting descents.  Had to IRAN with Precise Flight.  Work like a champ now.

Not cheap, but "Quality is not Expensive,    Its Priceless"

;-)

[IvanP]

I like the simplicity of the older vacuum driven speedbrakes. Simple actuator and couple of cables and springs. Of course, the main drawback is the need for vacuum pump and the inability to find replacement parts.  

[JimK]

I sent the following email to Precise Flight asking for their help:

My equipment:

Airplane Mooney M20R S/N 29-0490

P/N 010S0059-73 Rev C, Serial #984455 right hand cartridge.

P/N 010S0059-74 Rev C, Serial #984456 left hand cartridge.

These two cartridges look identical except for the location of the drain tube.   

Malfunction:

When activated with the button on the yoke the-74 only deploys about ¾” and stays there while the -73 fully deploys.  A few seconds later both retract very quickly indicating that the system has automatically removed power from both.  Note: Initially this malfunction was intermittent (sometimes the above malfunction existed, sometimes both fully deployed like they are supposed to).  Just recently this malfunction exists all the time now. 

Troubleshooting:

First step: I thoroughly cleaning both sides of all connectors; Three connectors on the Asymmetric Logic Control (ALC) and one connector on each wing cartridge.  Malfunction still exists.

Next step: Swapped the -73 & -74.  Malfunction still exists. 

Next step:  Swapped connectors on the ALC, left to right and right to left.  Malfunction still exists. 

Next step: I borrowed a known-good -73 cartridge off of a friend’s airplane of the same model.  I tried all six combinations and found the following:

1. My -73 on the right, my -74 on the left.  Original configuration, malfunction exists.

2. My -74 on the right, my -73 on the left.  Malfunction exists.

3. His -73 on the right, my -74 on the left.  Functions normally.

4. His -73 on the left, my -74 on the right.  Functions normally.

5. His -73 on the right, my -73 on the left. Malfunction exists.

6. His -73 on the left, my -73 on the right.  Malfunction exists.

These results led me to believe something is malfunctioning in my -73.  Also, I think it verifies that my -74 is good since it works as designed when mating it with a perfectly functioning -73.

I’ll fill y’all in on the final result when I get word back from Precise Flight.

[Pinecone]

My crystal ball says they will want you send in all the parts of your system for repair/reconditioning.

[TheBearFlies]