Demands are transmitted via power-by-wire and fly-by wire data bus links, modified automatically as they pass through engine and auto-flight computers, with no manual reversion
facilities as there were on the Concorde.
In the subsequent test flight the crew partially lost control of the aircraft during a manual reversion
check with the hydraulic power to the control actuators switched off, but managed to regain control when it was restored.
The aircraft was therefore significantly out of trim during the post-maintenance test flight and it was that which initiated the pitch-down incident during the manual reversion
At that point, she decided to put the plane into manual reversion
, which meant she was flying the aircraft without hydraulics.
We have taken out manual reversion
systems on most of our key communication, power and switching systems.
The ailerons are pushrod-operated by actuators mounted over the engine, and have manual reversion