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  #1  
Old 10-30-2022, 10:27 AM
homeap homeap is offline
 
Join Date: Apr 2013
Location: OFallon,IL
Posts: 21
Default Electric trim blowing fuse

I have a 2012 RV-12 that I purchased flying one year ago. When I turn on the master it immediately blows the electric trim fuse. I have looked in the panel for burnt wires and did not find anything. I have the Dynon Skyview touch system with auto pilot. I will be looking at the KAI as well as wiring schematics but I wanted to see if there were any known areas or suggestions that could cause an issue. I greatly appreciate your input.
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  #2  
Old 10-30-2022, 11:28 AM
Mich48041 Mich48041 is offline
 
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Location: Riley TWP MI
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Break an old fuse apart to get the metal terminals. Solder a wire to each terminal and plug the terminals into the fuse panel. Now connect a test light to the wires that you soldered. Use a test light that does NOT have an internal battery. Possibly this one from Harbor Freight: https://www.harborfreight.com/612v-c...ead-63603.html
When you turn on the master switch, the test light should illuminate if there is a short circuit. Now watch the test light as you wiggle wires and disconnect D-Sub connectors.
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  #3  
Old 10-30-2022, 11:57 AM
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Piper J3 Piper J3 is offline
 
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homeap - You're fairly new to the forum, so I'll just pipe-up here and tell you Joe is excellent at electrical troubleshooting. He'll stick with you until you find and fix the problem. VAF is your friend....
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Jim Stricker - EAA #499867
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80 hrs Flying Aeronca Chief 11AC N86203
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Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 830

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Old 10-30-2022, 04:12 PM
homeap homeap is offline
 
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Joe and Jim,

Thank you so much for the input, I will purchase one from Harbor freight and get started. If you think of any other suggestions, let me know.
Thanks again!

Russ
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  #5  
Old 10-30-2022, 07:09 PM
Mich48041 Mich48041 is offline
 
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Russ,
Below is a schematic of a RV-12 stabilator Trim circuit.
This version may or may not be for your aircraft. It is the only SkyView version that I have.
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  #6  
Old 10-30-2022, 10:03 PM
DHeal DHeal is offline
 
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Location: Windsor, California
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I would remove the tailcone fairing and carefully look at each wire that connects to the trim servo motor. These are very thin wires and one could easily be shorting on a nearby ground.
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  #7  
Old 10-31-2022, 07:53 AM
Mich48041 Mich48041 is offline
 
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Russ, Search Amazon for "B01H70U690". It is an automotive circuit tracer for $27.90
I don't have this one, but it looks like it can help find a short circuit.
Connect it as I described in post #2 above, instead of a test light.
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  #8  
Old 10-31-2022, 08:37 AM
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Piper J3 Piper J3 is offline
 
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I wouldn't discount the Ray Allen trim servo itself. Internal workings of the servo are minimal at best...
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Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 830

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father - CFI) - USAAF 1st Lt. Captain B-17H
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  #9  
Old 10-31-2022, 12:20 PM
NinerBikes NinerBikes is offline
 
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Also check the service bulletins, there is a limited number of hours allowed on the trim motor.

1.A bushing needs to be added, to the shaft, to prevent bending or flexing.

2. The motor needs to be replaced outright with an upgraded trim motor, after so many hours, not sure if it's 600 or 1000.
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  #10  
Old 10-31-2022, 01:29 PM
Mich48041 Mich48041 is offline
 
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It is unlikely that the short circuit problem is in the tail because the trim fuse blows when
the master switch is turned on, even though the trim switch is not pressed.
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