Originally Posted by
Weads
The Bell 407 RFM states that for a FADEC RESTART FAULT : When throttle is repositioned to idle stop (during engine shutdown) the PMA will go offline and engine may flameout. The PMA goes offline when the NP goes below 85% but the FADEC should still be supplied by DC battery/gen power. So my question is why would the engine flameout at idle with a RESTART FAULT? Thank you for any insight!
but the FADEC should still be supplied by DC battery/gen power
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.