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  #1  
Old 06-04-2023, 02:14 PM
Crbunt Crbunt is offline
 
Join Date: Sep 2021
Location: West Terre Haute IN
Posts: 16
Default Legacy 12 smoke and fumes

I have a 2011 12 and am not the builder. Been running great until this morning. Started out with getting A/P error on start. Wouldn't reset and couldn't shut down from AP74. Eventually it did reset and everything was good. Taxied out to do run up and that's when fun began. RPM to 4000 A side off and about 120 drop. Back on and up to 4000, B side off and it dropped about and 150 and sounded kind of rough. B side back on and that's when white smoke started flowing out of panel below the rocker switches. Immediately shut and down..after grabbing fire extinguisher..just in case. The smoke continued for about 10 seconds after shutdown.
Took back to hanger and started opening things up. Found no indications of fire or heat. Upon further inspection found an oily residue under rocker switches. Since there is a large electrolytic capacitor just above that area I assumed it had failed and was leaking. I have it all apart and it doesn't seem to be bulged or leaking. Next step is dissembling and removing from the board for test.
I'm wondering if this something anyone else has had to deal with and if it's just easier to order the entire assembly. It looks like it was built by Vans as the pcb board has their imprint on it.
I'm trying to find a part number to see if it's even available. Attached are a couple of pics.
Any help or pointers would be appreciated
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  #2  
Old 06-04-2023, 02:48 PM
Bob Y Bob Y is offline
 
Join Date: Jul 2017
Location: Piedmont, SC
Posts: 556
Default

That part number is AV CONTROL BOARD-12, but unless youre willing to shell out $850 for a new one, you might want to take a closer look at that capacitor. Id even replace it before buying a new board.
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  #3  
Old 06-04-2023, 04:13 PM
Crbunt Crbunt is offline
 
Join Date: Sep 2021
Location: West Terre Haute IN
Posts: 16
Default yike...

That's the plan for now..I told the wife I would be surprised if it was less than $1000 for a replacement. Thanks for the info. I'll post what I find after testing the cap.
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  #4  
Old 06-04-2023, 04:58 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 10,339
Default

Quote:
Originally Posted by Crbunt View Post
I have a 2011 12 and am not the builder. Been running great until this morning. Started out with getting A/P error on start. Wouldn't reset and couldn't shut down from AP74. Eventually it did reset and everything was good. Taxied out to do run up and that's when fun began. RPM to 4000 A side off and about 120 drop. Back on and up to 4000, B side off and it dropped about and 150 and sounded kind of rough. B side back on and that's when white smoke started flowing out of panel below the rocker switches. Immediately shut and down..after grabbing fire extinguisher..just in case. The smoke continued for about 10 seconds after shutdown.
Took back to hanger and started opening things up. Found no indications of fire or heat. Upon further inspection found an oily residue under rocker switches. Since there is a large electrolytic capacitor just above that area I assumed it had failed and was leaking. I have it all apart and it doesn't seem to be bulged or leaking. Next step is dissembling and removing from the board for test.
I'm wondering if this something anyone else has had to deal with and if it's just easier to order the entire assembly. It looks like it was built by Vans as the pcb board has their imprint on it.
I'm trying to find a part number to see if it's even available. Attached are a couple of pics.
Any help or pointers would be appreciated
I have worked with this assembly quite a bit and this is the first time I recall that it looks like the capacitor has failed in this manor.
Another clue is that it appears that the two plastic tie wraps that were used to anchor it to the pcb, have melted.
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Hubbard, Oregon
Formerly of Van's Aircraft Engineering Prototype Shop
FAA/DAR, A&P, EAA Technical Councelor
RV-6A (aka "Junkyard Special ")
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  #5  
Old 06-04-2023, 05:31 PM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 2,987
Default

If you pulled enough current to make smoke, and no fuses blew, then I would begin looking at circuit board traces. That much current would cause traces to heat and lift off the surface of the board.
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Jim Stricker - EAA #499867
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Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 890

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  #6  
Old 06-04-2023, 08:52 PM
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Tony Kirk Tony Kirk is offline
 
Join Date: Apr 2005
Location: KDUH
Posts: 162
Default UVR1E223MRD 22000uF Electrolytic Capacitor

I posted the capacitor number and link in this thread. DigiKey has them for less then $6.00 ea.
https://vansairforce.net/community/s...d.php?t=216874
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Van's Aircraft Tech Support
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RV-7 N777RV, AirVenture Kitbuilt Bronze Lindy Award 2022
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  #7  
Old 06-04-2023, 08:55 PM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,540
Default Legacy RV-12 capacitor

There is a 30 amp fuse between the capacitor and the battery.
That fuse won't blow easily.
There is NO fuse between the capacitor and charging system
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RV-12 Flying
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  #8  
Old 06-04-2023, 10:16 PM
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rcarsey rcarsey is offline
 
Join Date: Jul 2012
Location: Winfield Park, NJ
Posts: 489
Default

I'm sure you would have noticed, but no chance your voltage regulator took a dive and was giving > 25v to the bus? I always see electrolytic caps die first on circuit boards.. so I'm not surprised.. but am surprised that any.. even the shoddy chinesium ones would fail at (whatever your TT is)
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RV-12iS (N713) / Completed 12/2020 / 510hrs and counting
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  #9  
Old 06-05-2023, 05:45 PM
Crbunt Crbunt is offline
 
Join Date: Sep 2021
Location: West Terre Haute IN
Posts: 16
Default Followup

I've ordered a voltage regulator. Just in case. The ties were cut by me to read the info on the capacitor. The traces look fine and there were no fuses blown. First thing I checked. I've ordered the replacement cap so we will see if I still have any soldering skills left to replace it. The plane just hit 500 hours. We flew it for 1.5 hours the day before with no indications of any issues. So the plan is to replace the cap Reassemble everything..all 200 screws!...and test run it. If there are any other issues then I'll probably order the entire board from Van's and go from there...I'm not getting any younger and I need to get flying!
Thanks for the input..really helps to have more people to help think things through.
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  #10  
Old 06-06-2023, 07:20 AM
bobg56 bobg56 is offline
 
Join Date: Nov 2018
Location: Peachtree City, GA
Posts: 327
Default

I believe that Cap is for noise filtering. Rotax require one for radio interference.
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