Autotrim/elevator failure on A320?
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Autotrim/elevator failure on A320?
Hiya,
This is something that has been needling me for a while. Last Oct I had a 2 hour session in a fixed base A320 simulator in Berlin. The simulator is not certified for real world training. During my full flight - EDDF to EDDT, and established on final at around 1000ft, I disconnected the autopilot in preparation to fly a manual landing - and the aircraft proceeded to fall out of the sky like a stone. The inevitable accident was, at least for me, unrecoverable! The explaination given by the instructor was that they had been experiencing problems with the autotrim of the simulator and he had forgotten to adjust the trim in readiness for the autopilot disconnect (he forgot to tell me about this also!). There were no warnings on the ecam of any kind to indicate a fault. I have flown the same flight on my home sim a number of times (microsoft FSX and wilco A320 Evolution) and set the elevator to fail, as unable to set an actual autotrim failure, and again got no indication on the ecam. The difference on my home sim was that there was some indication of a problem in the behaviour of the aircraft whilst on autopilot and with the elevator failed - a kind of meandering approach and a high nose up pitch developing. On disconnecting the autopilot at home, the aircraft again headed for the ground but not as suddenly as in the Berlin sim. I manage at home to land, with difficulty.
Therefore, my questions are, on the real aircraft, if there is an autotrim failure, is there any sort of warning on the ecam or an aural warning sounded? If not, and the autopilot is disconnected at a similar altitude as mine in the Berlin sim, would the aircraft fall as suddenly, and would it be recoverable? I recoginise that there will be differences in the Berlin fixed based sim, my home sim, a certified simulator and the real aircraft!
Sorry for the long winded post, but I'm genuinely curious to know the answer.
Regards,
Rory
This is something that has been needling me for a while. Last Oct I had a 2 hour session in a fixed base A320 simulator in Berlin. The simulator is not certified for real world training. During my full flight - EDDF to EDDT, and established on final at around 1000ft, I disconnected the autopilot in preparation to fly a manual landing - and the aircraft proceeded to fall out of the sky like a stone. The inevitable accident was, at least for me, unrecoverable! The explaination given by the instructor was that they had been experiencing problems with the autotrim of the simulator and he had forgotten to adjust the trim in readiness for the autopilot disconnect (he forgot to tell me about this also!). There were no warnings on the ecam of any kind to indicate a fault. I have flown the same flight on my home sim a number of times (microsoft FSX and wilco A320 Evolution) and set the elevator to fail, as unable to set an actual autotrim failure, and again got no indication on the ecam. The difference on my home sim was that there was some indication of a problem in the behaviour of the aircraft whilst on autopilot and with the elevator failed - a kind of meandering approach and a high nose up pitch developing. On disconnecting the autopilot at home, the aircraft again headed for the ground but not as suddenly as in the Berlin sim. I manage at home to land, with difficulty.
Therefore, my questions are, on the real aircraft, if there is an autotrim failure, is there any sort of warning on the ecam or an aural warning sounded? If not, and the autopilot is disconnected at a similar altitude as mine in the Berlin sim, would the aircraft fall as suddenly, and would it be recoverable? I recoginise that there will be differences in the Berlin fixed based sim, my home sim, a certified simulator and the real aircraft!
Sorry for the long winded post, but I'm genuinely curious to know the answer.
Regards,
Rory
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Interesting question.
I normally steer clear of this forum , as , despite nearly 10,000 hours PIC A320/330 my technical knowledge leaves something to be desired.
However until someone more dedicated and wiser than myself comes along , and , as no-one has answered you yet , and I have the books I shall make a contribution.
The 'autotrim' of the elevators is taken care of by the horizontal stabiliser . There is a trim wheel by the centre pedestal on the flight deck which moves automatically when commanded by the commuters ( ELACs possibly ).
The scenario you describe is therefore caused by a Stabilizer jam . There are two procedures - one where the ELACs recognise the problem and ECAM comes up , and , interestingly from your point of view, one where the system fails to recognise the problem and when the autopilot is taken off the aircraft may be out of trim. If the situation is not realised til 1000 feet then the aircraft may be way out of trim and robust elevator movement will be necessary . I am not sure whether the situation will be easily recognisable before the AP is off although we are used to the trim wheel moving on the approach as the configuration changes.
I normally steer clear of this forum , as , despite nearly 10,000 hours PIC A320/330 my technical knowledge leaves something to be desired.
However until someone more dedicated and wiser than myself comes along , and , as no-one has answered you yet , and I have the books I shall make a contribution.
The 'autotrim' of the elevators is taken care of by the horizontal stabiliser . There is a trim wheel by the centre pedestal on the flight deck which moves automatically when commanded by the commuters ( ELACs possibly ).
The scenario you describe is therefore caused by a Stabilizer jam . There are two procedures - one where the ELACs recognise the problem and ECAM comes up , and , interestingly from your point of view, one where the system fails to recognise the problem and when the autopilot is taken off the aircraft may be out of trim. If the situation is not realised til 1000 feet then the aircraft may be way out of trim and robust elevator movement will be necessary . I am not sure whether the situation will be easily recognisable before the AP is off although we are used to the trim wheel moving on the approach as the configuration changes.
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Many thanks for taking the time to reply. Presumably then if this scenario occurred for real and at a similar altitude to mine in the sim - 1000ft -an accident could be avoided, when you say robust elevator movement would be required? As a non flyer myself, I had no chance of recovering, as it all happened so fast - the instructor also had no chance to react quickly enough. Also, If the aircraft is flown to minimums before AP disconnect then this could then perhaps turn into a non survivable accident, or crash landing? Is this something that is actually practiced in the simulator? If you dont reply further, then again, thankyou very much for having already replied.
Rory
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Had you had the opportunity to repeat the approach with this problem a few times you would have become quite adept , I am quite sure . Flying is not natural nor intuitive for most humans - it needs training and practice.
No-one who flew aircraft 30 years ago would ever take an autopilot out without anticipating an out of trim condition. Autopilots would frequently drop out of their own accord due to turbulence and an inability to autotrim quickly enough .
I have checked on the A330 and a stabiliser jam is always assumed to lead to alternate law and hence ECAM warnings and procedures . One would hope that on the A320 the warnings would come with a severe out of trim condition and the procedure with no warnings would apply in a mild out of trim condition , although I appreciate that this does not fit with your experience .
A stabiliser jam is assumed to be recoverable although with restricted pitch authority.
The worst case scenario that you describe is theoretically possible - but there is no recorded case of it ever happening , which says a lot for Airbus, professional pilots, luck and statistics.
No-one who flew aircraft 30 years ago would ever take an autopilot out without anticipating an out of trim condition. Autopilots would frequently drop out of their own accord due to turbulence and an inability to autotrim quickly enough .
I have checked on the A330 and a stabiliser jam is always assumed to lead to alternate law and hence ECAM warnings and procedures . One would hope that on the A320 the warnings would come with a severe out of trim condition and the procedure with no warnings would apply in a mild out of trim condition , although I appreciate that this does not fit with your experience .
A stabiliser jam is assumed to be recoverable although with restricted pitch authority.
The worst case scenario that you describe is theoretically possible - but there is no recorded case of it ever happening , which says a lot for Airbus, professional pilots, luck and statistics.
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Well, again, thankyou for that informative reply, I appreciate you taking the time. I'm currently saving for a couple of hours in a full motion A320 sim and will be asking if I can repeat my experience.
Rory
Rory
