Re: Aileron control on Airbus

Date:         28 Jul 97 01:13:28 
From:         Pete Mellor <>
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Ian McAndrew wrote:
>> On a flight to Italy recently, my first on an Airbus, I was looking at
>> the wing and it appeared to me that there were no conventional ailerons.
>> There was a control surface close to the fuselage which showed a lot of
>> activity during the approach but only in a downward direction

Ken Ishiguro replied:
> I am not an Airbus expert, but many aircraft use an inboard "cruise
> aileron" at cruise speeds which is coupled to the autopilot and is in
> fairly constant motion to maintain wings-level.  At intermediate
> airspeeds, flaps and spoilers are used to generate roll.  At approach
> speeds, conventional outboard ailerons are used.  (The outboard ailerons
> on most older generation aircraft are mechanically locked- accidental
> full deflection at cruise speed would not be pretty!)
> On an A320, I noted the outboard ailerons were used at all airspeeds and
> there appeared to be no inboard ailerons.

Does Ian recall which Airbus he was on? The A320 has outboard
ailerons only. These are controlled in normal flight through
the Electrical Flight Control System (EFCS). The fault-tolerant
design of the computer boxes in the EFCS was chosen largely
to prevent uncommanded or excessive flight control surface
movement of the type Ken describes.

I once flew on an Aeroflot A300 from LHR to Tokyo. I was struck
by the different configuration of the flight control surfaces
on the wings compared to those on the A320, but can't recall
exactly what they looked like.

(BTW: Aeroflot were true to form. They ran out of vodka before
we reached Moscow! :-)

Peter Mellor, Centre for Software Reliability, City University, Northampton
Square, London EC1V 0HB, UK. Tel: +44 (171) 477-8422, Fax: +44 (171) 477-8585