First post in DA website!

[WOW2]

Hello everyone,

This is my first post in DiamondAviator.net website and thanks for your time going through my post here.
I am posting because I had couple questions on electrical system on DA42NG and I hope this does not "lower" the quality of the forum itself..

The Avionics bus, as we all know it powers GIA2 with autopilot along with other optional avionics but where does it states that autopilot 'servos' and GIA2 are under part of Avionics bus? I tried look into Maintenance manual but found none.

Secondly, when the L/R engine master is on, I found out an interesting information that it connects L/R alternator field to the ECU backup battery and does anyone know why and what this is for?

Lastly, if we use the emergency gear extension lever, do we have to recharge the pressure in the Schrader Accumulator?

Thanks all for taking time.

[CFIDave]

Welcome to the forum.

1. Take a look at the end of Diamond's AMM (maintenance manual for the DA42NG) on their Austrian website, and you'll see all of the schematics for the aircraft including G1000/GFC700 autopilot servos.
http://support.diamond-air.at/da42_ng_a ... 73ab0.html

2. Without receiving field current, alternators can't put out any current of their own. So to recharge the main battery (assuming it were totally discharged), the alternators instead get their field current from the same backup batteries that also keep the ECUs running in the event of a discharged main battery.

3. I've always wondered about this also, so I haven't ever pulled the emergency gear extension lever. Maybe someone else knows.

[WOW2]

Thank you CFIDave for your time!
I looked at the AMM for DA42NG and It made sense a lot more than when I tried to understand without the schematic.

Regarding the second question, I looked back into my high school Physics class theory and it also made sense but if the ECU back up batteries(for DA42NG-VI) under passenger seat provide field current for excitation of alternator, don't they have to be recharged back to its full capacity?

WOW2

[CFIDave]

if the ECU back up batteries(for DA42NG-VI) under passenger seat provide field current for excitation of alternator, don't they have to be recharged back to its full capacity?

Yes they do. When the ECU Backup Battery Relay is tripped (due to low main battery voltage), the backup batteries for the ECU are connected to the same charging circuits as the main battery, and thus also get charged by the alternator(s).

[WOW2]

Thanks Dave, I looked at the Schematic for L/R ECU and I think I need to do some more research with electricity symbols used in design. It was so complicated that I could hardly understand that the ECU back up relay closes to charge the battery back to normal capacity. For the accumulator recharging scenario, I will have to leave it for someone else but I will keep looking for the answer and post here If I do find one!