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Old 02-24-2020, 06:58 PM
FL Flier FL Flier is offline
Join Date: Jan 2019
Location: FD88 - Aero Acres Airpark, Port St. Lucie, FL
Posts: 6
Default Electrical system going off & on

My electrical system has shut off and immediately come back on several times. Itís always in flight, voltmeter and ammeter normal. When it happens, everything electrical momentarily shuts off and is back on instantly, just like flicking the master. Itís also blown the 20A landing light fuse twice.

The electric pitch trim also stopped working; the breaker stayed in, and there is a click from the relay below the pilot seat when I hit the switch, but the trim tab servo is silent.

Until I can get an A&P whoíll work on the bowl of spaghetti behind my panel, where should I be starting with troubleshooting? Master switch and battery connector?

There is also a lot of noise in the intercom when the landing lights and/or strobes are on, plus a voltage spike when transmitting on the GNS430W. I understand the last problem to probably be unshielded wiring.

At this point, Iím looking to get the electrical reboot problem, trim and landing light fuse issues fixed. Everything else can wait until whenever (if) I have time, get the skill and help to completely re-do the electrical system.
2004 RV-8A N102RV
Aero Acres FD88
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Old 02-24-2020, 07:08 PM
Robin8er Robin8er is offline
Join Date: Sep 2015
Location: Socal
Posts: 405

Did you build or buy?

It sounds like the master switch itself might be momentarily turning off, maybe due to a loose wire/connector.

Its a slow way to do it, but just check every single wire connector on both ends. I'd start with the master switch/solenoid and the landing light since it blew a fuse.
RV-8 N695RA flying
Working on an RV-4

Born to fly, forced to work
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Old 02-25-2020, 08:31 AM
DennisRhodes DennisRhodes is offline
Join Date: Jul 2007
Location: Taylorsville, Ga
Posts: 739

I would start troubleshooting with the landing light breaker operation. A ground that will take out a 20A breaker will also result in a spike on the balance of the system. that might be some of the other on/ off you are seeing. Locate the circuit for the landing light, isolate it and began an inspection for grounds. This might include powering that circuit up from another breaker protected source ( Other than the aircraft power) to be able to find that ground.

I will never forget a foil chewing gum wrapper someone put into a rear seat cigarette lighter in my car!!!!
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RV9 N908DR
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Old 02-25-2020, 08:39 AM
lr172 lr172 is offline
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 4,726

Originally Posted by Robin8er View Post
Did you build or buy?

It sounds like the master switch itself might be momentarily turning off, maybe due to a loose wire/connector.

Its a slow way to do it, but just check every single wire connector on both ends. I'd start with the master switch/solenoid and the landing light since it blew a fuse.

This where I would start. Not too many things that wipe out the entire electical system. Could be the solelnoid activation wire/circuit, as mentioned, or the solenoid itself. It could also be a loose wire (battery, solenoid, main ground, etc.)

You have other strange symptoms that may be unrelated and require further attention. The radio voltage spike and blown ldg light fuse point to a potential problem where your battery connects to airframe ground. If that is loose, it could also be creating your complete system shut down, during points of turbulence or vibration.

RV-6A / IO-320, Flying as of 8/2015
RV-10 in Phase I

Last edited by lr172 : 02-25-2020 at 08:41 AM.
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Old 02-25-2020, 08:50 AM
rongawer rongawer is offline
Join Date: Dec 2007
Location: Brentwood, CA
Posts: 612

Just going on your statement about going off, and then immediately back on, I agree with checking the master switch and battery relay. Circuit breakers and fuses don't auto reset (at least not the one's we use in airplanes...), so I'd check for loose contacts and broken or weak springs in the switches and relays.
Ron Gawer

- RV10, Build in progress.
- RV12, N975G, "The Commuter"...many great hours and happy landings so far.
- Several others that are now just great memories for me.
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Old 02-25-2020, 09:31 AM
fl-mike's Avatar
fl-mike fl-mike is offline
Join Date: Jul 2005
Posts: 1,253

Check the engine ground strap and battery connections
Mike W
Venice, FL
RV-6A. Mattituck TMX O-360, FP, GRT Sport EFIS, L3 Lynx NGT-9000
N184WM reserved (RV-8)....finishing kit in progress. Titan IOX-370
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Old 02-25-2020, 02:47 PM
Djgeib Djgeib is offline
Join Date: Jun 2012
Location: Fernandina, Fl
Posts: 72

I concur with Mike. Check your battery terminals. Happened to me once and it was a loose battery terminal
Doug Geib
RV8 empennage complete
QB wings started
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Old 02-25-2020, 04:48 PM
rwarre rwarre is offline
Join Date: Jul 2007
Location: Wray, Co
Posts: 555
Default similar issue

A while back I had electrical intermittent problems and after troubleshooting various systems, found the battery wire was touching the metal next to my fuse panel which created the intermittent. Only happened when flying and the vibrations of the engine caused the problem.
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Old 02-26-2020, 05:50 AM
FredMagare FredMagare is offline
Join Date: Mar 2006
Location: Kyle, TX
Posts: 561

As others have suggested - Look for loose connections. Start at the battery and work toward the bus then to the master switch to ground. Also check connections on the master solenoid and ground. Lightly pull on the terminals. Since it happens in flight something MUST be coming loose. (A less likely cause may be that one of those wires is broken inside the insulation and breaking contact during flight. Check how the wires are secured to see if any key wiring could be experiencing excess movement during flight.)
Fred Magare
GySgt, USMC (Ret.)
Frederic.magare "at"
RV-9A Firewall Forward
[Engine purchased]
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Old 02-26-2020, 01:18 PM
springer springer is offline
Join Date: May 2012
Location: AZ/MN
Posts: 358

Battery master switch. This happened to me exactly as described. It turned out to be my cheap $4.95 master switch itself and not the wiring.
RV-4 '88-'09 Built & Sold
RV-8 Purchased
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