Originally Posted by
RVDT
Which would be the issue. EEC is supplied with battery/gen power for start. There are diodes on this supply so that the battery/gen can supply power but not the other way around as the PMA should not be able to power the helicopter main bus.
When the throttle is at idle the FADEC would go to MANUAL with no power source and due to the follow up characteristic in the HMU it may go below minimum fuel flow to sustain the engine and it may flameout.
If you have no battery/gen power for EEC to start it then you have a FADEC RESTART FAULT.
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%