Originally Posted by
NutLoose
FADEC issues on bizjets are more common as they are not designed and certified to the same level as commercial airliners. In this case, the FADECs were run off aircraft power - no dedicated generator - so when the aircraft power glitched, it quit. That design would never pass muster on a Part 25 commercial airliner.
There was another bizjet crash 10 or 15 years ago when the pilots somehow managed to move the thrust levers 'too far' during takeoff and the thrust lever resolvers went 'out of range' high, so the FADECs defaulted to idle. We immediately had to demonstrate to the Feds why that would never happen on a Boeing. Thrust lever resolvers are normally designed to operate between about 5 and 85 degrees (since the resolver basically works by comparing 'sine' and 'cosine' to determine the angle - so the resolution gets lousy near zero and 90.
For Boeing installed FADECs, we don't have the resolver go 'out of range' if exceeds the maximum angle - rather we keep it valid, and if goes past 90 it just goes down the back side of the sine/cosine curve.