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Easa Directive On A330/A340 Autopilot  
User currently offlineAF2323 From France, joined Aug 2007, 122 posts, RR: 0
Posted (5 years 5 months 3 days 22 hours ago) and read 6009 times:

EASA has just released on december 22th 2010 an airworthiness directive on Airbus A330's and A340's autopilot, relating to speed measurement inconsistencies :


When there are significant differences between all airspeed sources, the
flight controls of an Airbus A330 or A340 aeroplane will revert to alternate
law, the autopilot (AP) and the auto-thrust (A/THR) automatically disconnect,
and the Flight Directors (FD) bars are automatically removed.

It has been identified that, after such an event, if two airspeed sources
become similar while still erroneous, the flight guidance computers will:
- Display FD bars again, and
- Enable autopilot and auto-thrust re-engagement
However, in some cases, the autopilot orders may be inappropriate, such as
possible abrupt pitch command.

The directive is issuing a new procedure to make sure the speed is correct before engaging again the autopilot.

The probability of this event to happen is probably very thin, but I imagine under the same conditions it is possible that two probes are giving the same wrong information. Designers of the system probably have thought that this case would never happen and that it was useless to make a procedure to deal whith that...

I would be very interested to know if this event ( two speeds being equals while being wrong) was anticipated on other planes, with a specific procedure or a different behavior of the system. This directive doesn't apply to the A340-500 and 600 for instance... If someone in the know can enlighten us...

2 replies: All unread, jump to last
User currently offlineAesma From Reunion, joined Nov 2009, 8805 posts, RR: 15
Reply 1, posted (5 years 5 months 3 days 18 hours ago) and read 5930 times:

So, is someone thinking that it is linked to AF447 ?

New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
User currently offlineweb500sjc From United States of America, joined Sep 2009, 942 posts, RR: 0
Reply 2, posted (5 years 5 months 3 days 10 hours ago) and read 5788 times:
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How about the quantas flights with the pitch problems?

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