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Electrical system going off & on

FL Flier

Active Member
My electrical system has shut off and immediately come back on several times. It?s 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. It?s 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 who?ll 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, I?m 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.
 
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.
 
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!!!!
 
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.

+1

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.

Larry
 
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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.
 
I concur with Mike. Check your battery terminals. Happened to me once and it was a loose battery terminal
 
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.
 
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.)
 
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.
 
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