MGL Avionics User Forum

Have had my Voyager in a Rv7a for 4years now. Today it would crash several times when I started the engine and then stabilized after take off. Crashed one more time during the flight. When it crashed it restarted immediately like there was a voltage loss. Help needed to troubleshoot

Hi Rwarre,

Firstly, do you have a back up battery supply for your EFIS in your plane?
Secondly, is your battery back up system serviceable?

If you answered yes to both these questions, then the following may not be your issue.

But if it's no to either, I would try checking the connectivity of the main power supply to your EFIS and by checking both the Positive and Negative wires to the EFIS D-Sub and then check the voltage to the D-sub.

If all seems O.K, I would do the following. If the cabling is automotive type wire with softer type plastic insulation, this softer plastic insulation can stretch and let the wire break internally through vibration.

So check the positive and negative wire are not going open circuit, this may only be happening under vibration or with rough air.

So it may be a simple loss of power to your EFIS. So check the Voltage at the EFIS D-Sub when doing this, move the wires before the D-sub in your aircraft wiring harness in all different directions whilst watching your multimeter closely to see if the voltage drops or changes even for a split second.

Take your time in moving the wires around, if you find nothing, maybe try bending the wires a little tighter in different directions just to make sure.

When testing for this type of internal break, the secret is to make up a D-Sub with long wires soldered to it, so it can plug into your aircraft's D-Sub and connect this to your multimeter using bridging clips.

That way if you see any voltage change, you can be pretty sure it's happening from the movement of the aircraft wiring, not the connections to the multimeter.

Hope this is of help.

Cheers
JimJab.