lilflyboy262 wrote:
Scenario 2. Im unfamiliar with that aircraft, so do not know if there are failsafes with how the flaps deploy, or what settings they use on take-off. So the pilots are low to the ground just after take off, through 300ft, captian calls for flaps to be retracted. One goes up. One stays down. Next moment we have assymetric flaps and the plane is wanting to roll onto its back.
Performance 'A' defines the lowest Acceleration Height as being 400ft AGL.
For a number of reasons, most large jet operators (
typically) nominate lowest Acceleration Heights of 800ft, or 1000ft, or 1500ft AGL.
Most jet aircraft types have flap/slat asymmetry detection & protection systems. In the event that, when commanding the flaps to move from one position to the next, where an asymmetry is encountered during that movement, the system should stop all movement at (
or very close to) the position where the asymmetry was detected; thus leaving the aircraft in a predominantly neutral position (
wrt any tendency to roll, due to unbalanced aerodynamics).
Now in the event that you 1) have an asymmetry and 2) the asymmetry detection system also fails, what will then happen is that part of the flaps/slats system will continue to move to the commanded position, whilst some other part remains in a stuck position. With unbalanced aerodynamic forces, there will certainly be some tendency for the aircraft to roll, but not so much that it can't be counteracted with either aileron or rudder.
The key here is that the flaps are normally moved in a progressive manner and that should allow plenty of opportunity to both detect & deal with any asymmetry that is not detected and locked out by a (
failed) flap asymmetry detection system.
And it somewhat goes without saying that the flight crew need to be vigilant for potential malfunctions when making changes to an aircraft's configuration.
lilflyboy262, yes, with an asymmetry there will be some tendency to roll, but it is unlikely to be some sort of flick-roll and therein it is most unlikely that the aircraft will be "wanting to roll on to its back", (
as you somewhat melodramatically put it! ). At its very worst you'd need both of the aforementioned failures, whilst continuing to command an ever increasing asymmetric condition via the flap lever, and then do nothing about it (
which would be a pretty outrageous set of circumstances, imho ).