Location: Quite near 'An aerodrome somewhere in England'
Posts: 20,206
A330/A340 EAD (AoA PROBES)
An EAD has just been released following an issue experienced by an A330 crew:
The EAD includes the narrative:
Quote:
An A330 aeroplane experienced a blockage of all Angle Of Attack (AOA) probes during climb leading to Autopilot (AP) disconnection and activation of the alpha protection (Alpha Prot) when Mach number increased.
The blockage of two or three AOA probes at the same angle may cause the Apha Prot of the normal law to activate.
Alors, qu'est que c'est un 'blockage' of an AOA probe? Does that mean blocked with foreign matter / ice / whatever, or is it some quaint Franglais referring to a stuck probe?
The EAD also states:
Quote:
Under normal flight conditions (in normal law), if the Alpha Prot activates and Mach number increases, the flight control laws order a pitch down of the aeroplane that the flight crew may not be able to counteract with a sidestick deflection, even in the full backward position.
Followed by the "No Sh*t, Sherlock" statement:
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This condition, if not corrected, could result in reduced control of the aeroplane.
You don't say!
Another piece of Froggldegook comes in the actual procedure and states:
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CAUTION RISK OF UNDUE STALL WARNING
I've heard of spurious stall warnings and have even experienced spurious stall ident and stick push at 500 ft in a much older 4-jet, I've taught 'incipient' stall recoveries and 'fully developed' stall recoveries, but never in 40 years have I ever heard of an 'undue' stall warning....
Once again it becomes clear that every Airbua FBW aircraft pilot should know how to get out of the normal law. As it seems the only safe way out of such mess. Regrettably Airbus will continue to refuse to tell us.
An EAD has just been released following an issue experienced by an A330 crew:
This only applies to the newer aircraft with the new AoA probe that is mounted on a raised area away from the skin.
Quote:
I've heard of spurious stall warnings and have even experienced spurious stall ident and stick push at 500 ft in a much older 4-jet, I've taught 'incipient' stall recoveries and 'fully developed' stall recoveries, but never in 40 years have I ever heard of an 'undue' stall warning....
Considering every aircraft flying is at risk of undue stall warnings, I am surprised that you have not heard of it (sensor issue, radome damage, bird strike, ADC issue etc). An example would be the 777 incident out of Perth https://www.atsb.gov.au/media/24550/...503722_001.pdf
Safelife - I sincerely hope you are not a A3xx driver! You have multiple way's of getting the machine into Alt or Direct law easily within a few seconds, all of which you can find in the FCOM.
As stated in the above post - Switch of multiple PRIMS or ELACS, or FAC 1+2
Not ideal in the slightest however not some big AB secret and something you should most definitely already know...
'Undue' is also defined as 'unwarranted'. Doesn't seem a huge leap of logic to suggest, therefore that an unwarranted stall warning is one which doesn't actually mean the aircraft is stalling...nothing to do with Froggledigook.
I have been following this shimmering thread that expands and contracts with time, with interest. There seems to be an almost obdurate unwillingness to understand the text of the EAD and of the Airbus concept of design and operation of aircraft. I have no problem with either, but then I operate Airbus aircraft and have done so for many years, and am familiar with the way they do things. It's not difficult, nor is it inherently dangerous, it is comprehensible and is designed to be so worldwide.
Considering every aircraft flying is at risk of undue stall warnings, I am surprise that you have not heard of it (sensor issue, radome damage, bird strike, ADC issue etc). An example would be the 777 incident out of Perth
I do agree with your comment, except that, if i read correctly the report, the activation of the stall warning and stick shaker devices was justified in the Perth 777 case.
Quote:
Originally Posted by NOLAND3
Safelife - I sincerely hope you are not a A3xx driver! You have multiple way's of getting the machine into Alt or Direct law easily within a few seconds, all of which you can find in the FCOM.
2 things i would like to see then :
A published Memory Item to get rid of undesirable protection activation
A single black guarded switch to trigger DIRECT LAW
In aviation it is frequently said that an experienced aviator is one that uses his exceptional knowledge in order to avoid having to use his exceptional skill.
The correlation to this thread is that I am able to understand (generally) what the people at airbus write, but I have to work at it sometimes.
The cynic in me suspects that it is not just a poor translation from French into technical English but a deliberate attempt to minimise adverse media coverage at the expense of clarity.
An undue warning seems much less emotive than a spurious warning when read as a newspaper headline!
The new bulletin tells us to switch off two ADRs to get in Alternate Law.
We don't want Direct law, direct law is dangerous
I believe switching off 2 ADR's puts you in ALT2 with roll direct, and evidently is the procedure used on aircraft flight checks to get to alternate law. You're 1/2 way to 'dangerous', be careful.
For academic reference only, I'd be curious how NOLAND3 or anyone gets to ALT1 using only cockpit switches?
Roll direct is hardly a dangerous thing. Pitch alternate is Ok, no danger at all.
Pitch direct is dangerous, however. Many people thing that reverting to Direct law is like reverting to a conventional flight control system, but pitch direct is nowhere near conventional.
Thank you mm43. I would be curious to hear more about the initial event and how the guys dealt with it ?
That Temporary Revision should also clearly specify how the procedure is meant to give back control to the pilots when protections do activate on unreliable data. Give back credit to the pilots.
Quote:
Originally Posted by M2002
Many people thing that reverting to Direct law is like reverting to a conventional flight control system, but pitch direct is nowhere near conventional.
bad day?
