AMP problems

[Gnomad]

Ok...

Took off today into a low ceiling to do some approaches. Got on top and went to lean the mixture on the engine page, when I noticed amps were reading +0. At least I didn't have GIANT red Xs like last Fall. .

I did a double take, tried to figure out what was going on. Battery was fine, breakers fine, swapped to my backup alternator (from premiere), but no change. Called departure back and told them was having alternator issues and would like to come back and land. Turned around, descended loaded up the approach, then was cleared. Went back to the engine page and amps were back to normal +10 or something. Once on the ground I parked and fooled around, all lights, fuel pump, draw way up. Lights pump off, draw back down. Couldn't duplicate so back to my hanger and shutdown. Then did a few restarts and got it to happen again for about a minute. Amps just dropped to +0 then later recovered to normal.

So...getting no warning messages or red X, battery way into the green etc... Anyone have experience with this? Sensor issue? Short in the wiring? Something not plugged in tight enough? Trying to get some ideas before heading to the mechanic.

Thanks in advance!

Eric

[hookem80]

Have not seen that problem in almost 6 years and about 700hrs of flying my DA 40. My ammeter always reads a +indication, usually +10 with the strobes on and normal load for G1000. If you are not seeing the red ALTERNATOR fail indication, I would believe the Alternator is functioning.

I would guess that you are having a ammeter sensor problem. Notice your volt meter indication, usually in the 26.5+ volts range when charging and somewhere below 24V when on battery only. So if you see the +0 indication again, what is the volt meter doing? If 26.5V+ you likely have an ammeter indication problem, if volts are lower and dropping you have a charging problem. This could be cross checked by switching to your back alternator.

Regards
Trey

N22QQ DA 40.447
KFTW KGDJ

[Gnomad]

Thx for the reply...

Volts are definately holding steady. Have a pic on my phone showing 28.0. Definately was watching, both in the air and on the ground for discharge from the battery, but it held steady well into the green, definately charging. No change at all in readings when I flip back and forth from main to backup alternator.

Someone suggested to me it could be the wiring harness, or to recycle the ALT breaker, but made no sense to me because of the second alternator in a completely different location. Somewhere the two meet, but I'm mechanically clueless, so...

Ammeter sensor seems to make sense since I would assume there is only one of those before hitting the battery.

Eric

[Rick]

This might help (see lower left corner).

DA4-9231-60-06p4.pdf

GEA71 Wiring

(427.06 KiB) Downloaded 244 times

[Gnomad]

Oh no...not the GEA71 unit again! That was the prime suspect during http://www.diamondaviators.net/forum/g1 ... %20madness but after replacing the problem persisted. Turned out to be a wire short.

Not smart enough to make sense of that diagram, but I do see what you are pointing at. Will definitely have it in hand when visiting the shop. Thx!

Eric

[Rick]

I think it's much more likely to be the "ALT AMP SENSOR" or the wiring between it and the GEA. The fatc that it comes and goes make me think loose connector, unseated pin, damaged wire, etc. Hopefully the diagram will give your shop a good starting point to track it down!

[Gnomad]

That's my hope too, unfortunately I don't trust my local shop to touch the G1000, so another trip to Dillon's seems to be in my future. *sigh*