A320 violent roll when disconnecting a/p

1st Official Post

    It seems the A320 has become unstable in roll after the last updates. It seems to be most severe at low altitude, eg on final approach.

    If i fly with a/p engaged and tracking an ils and i disconnect the a/p 4-5 miles out, the plane rolls sometimes to 90 deg bank in 2 seconds. Sometimes it banks left and other times it banks right.

    I end up in a heavy nose and wing down situasjon with overspeed. I have watched the flight control page and can not see anything abormal before i disconnect.

    Have tried restarts of AFS 2 and pc, no change.

    Raymond

    Quote from Jet-Pack

    This is a feature (what is it doing now???)

    Just kidding, I think that is an internal trim run away, I'll fix it. I tested the autopilot but it might be more prominent the longer you fly and the more turns you fly to one side. :)

    Sorry, I'll get to it as soon as possible. Use the autoland for now 8o

    Thanks. I always assume I am at fault. I have been married 32 years so it is easier that way.:)

    Noticed this too.

    Also, since the last update, the AP and A/T suddenly disengage during an autoland. It happens at about 100/200 ft above ground without a clear reason (no over- or underspeed etc). I follow the same procedures and never had this before, now it happens every time.

    Can anyone confirm this?

    • Official Post
    Quote from 7rAnzig7

    Also, since the last update, the AP and A/T suddenly disengage during an autoland. It happens at about 100/200 ft above ground without a clear reason (no over- or underspeed etc). I follow the same procedures and never had this before, now it happens every time.

    Never had that before, it should only disconnect when the glide slope is lost (goes to full deflection), e.g. due to a strong updraft. Which airport are you trying to land at? But even then the A/THR should remain engaged, that should only disengage with idle thrust or disarm with >CLB thrust

    Also I assume you are trying to land with LOC and G/S not with NAV and FINAL? Because the latter doesn't work in real life...

    Hmm, well I had it at different airports. I remember trying Zurich and San Francisco.

    I don't have that much knowledge, but I use a procedure that worked for me before. I create a flightplan, fly nav mode, press ils during flight. After I've started the descent and the localizer is set up, I press approach. It starts descending by itself (goes well in the path) and A/T manages the speed. I'm using flaps etc. The display does show g/s and loc on it. Everything seems to work and goes according to plan, and then... AP disengages, throttle increases (now that I think of it) and the rolling thing happens. It seems to come out of nowhere.

    If you need more info, I'll have to try again and come back to you.

    Thx!

    Edited once, last by 7rAnzig7 (August 29, 2017 at 4:58 PM).

    • Official Post
    Quote from 7rAnzig7

    AP disengages, throttle increases (now that I think of it) and the rolling thing happens. It seems to come out of nowhere.

    If you need more info, I'll have to try again and come back to you.

    Ah, that is a differnent issue then, probably. That has to do with the fly by wire changes as well.

    It sounds like A.FLOOR activates due to the high angle of attack, I might need to make that less sensitive. But you also don't have my latest version of that either, stay tuned.

    • Official Post
    Quote from Deltawing

    I have also had a.floor protection engaging several times after the last updates, never happened before.

    Maybe it kicks in to early(too high speed)?

    Well I used real world angle of attack numbers but they seem to be to small for our current flight setup or they are calibrated differently (some constant offset). Future updates will fix that, try to stay fast when doing tight turns.

    • Official Post
    Quote from bbrz

    Noticed a few errors concerning low speed / high AoA handling/performance.

    Did a few tests and I have the impression that alpha floor triggers always at approx 10° AoA regardless of flap/slat configuration.

    1. VLS, Alpha prot and Alpha max indications don't match the actual values. E.g. in clean config a.floor triggers with none of these indications in the vicinity.

    2. IRL A.floor changes with config 0 = 9.5°, 1+2 = 15°, 3 = 14°, full = 13° (conf 3 alpha.stall = 21°)

    3. Alpha.prot is at a lower AoA than alpha.floor which means that TOGA LK shouldn't engage if the AoA isn't already well withing the amber/black area on the speed tape.

    Yes it seems to trigger at 9.5° fixed and that is not good and I'm aware of it and already made a fix but that fix has to make it to the public yet, the current public version isn't the final result.

    And because of that 2 and 3) are solved automatically :)

    1. Well if all the protections trigger with angle of attack and the speeds are only updated with load factor that means the protections will trigger wll before the indicated speeds if you fly dynamically (e.g. pull full up)