On Avherald, it is said that the green hydraulic system is suspected to have failed.
This has the following main consequences:
- Landing gear operation is severely impaired. If down, it cannot be retracted any more, carrying a fuel consumption penalty of 180% in case of closed landing gear doors.
If it was retracted at the time of failure, it can be extended by gravity only, the landing gear doors will stay open after this. This will lead to a fuel burn much more than the 180% malus mentioned, the exact value is not published by Airbus.
- Main brake is unusable, alternate braking with antiskid remains available from yellow hydraulic.
- Nose wheel steering may or may not be usable depending on aircraft version: on the newer 320 series, it is driven by the yellow hydraulic, on the older ones by the green system.
- #1 reverser is unusable and will stay stowed.
- 2 of 5 spoilers per wing are unusable.
- Slats and flaps may be slow but operable
The other flight controls are unaffected in principle - they may lose one of their power sources but fall back on their respective alternate.
The FMS however calculates its fuel estimates based on the original performance model and does not know the impaired performance status of the aircraft. Manual calculation of endurance, range etc. is required - in case of open landing gear doors and therefore in absence of Airbus published data, fuel flow and ground speed is an appropriate starting point.
If so, there may well be some similarities to the well known
Hapag-Lloyd 3378 accident in this case.