Originally Posted by
Weads
I guess one thing I’m still hung up on RVDT is that you say the FADEC is supplied with battery power for start. PMA takes over at 85% nP depending on voltage of it and the battery/ gen taking which ever is higher. So that makes me ask the question of what powers the FADEC when the aircraft is at idle and with an nP less than 85%
The FADEC ECU is supplied by the 28VDC Bus from 0% NP until 85%NP is reached. Then it chooses between the PMA and the 28 VDC bus, whichever is higher.