A340 FBW Rudder!

[Sky Wave]

Was reading in this week FI magazine that Airbus are now producing A340's with a FBW controlled rudder. Does anyone know if there is still a mechanical fallback in the case of a total Electrical Failure.

[Notso Fantastic]

The whole point of FBW is to get rid of the heavy manual linkages, cables, etc. There doesn't seem to be much point in going to the expense of developing FBW and backing it up with hardware!

[tired]

Actually, Notso, the rudder on the 340 is purely mechanical (although yaw damping and trim is electric.) It's there as a Mechanical Backup in the event of failure of all flight control computers.

Sky Wave - I haven't read the FI article (and if it's in FI then it must be true, mustn't it.....?) but it would mean a large-scale redesign of the flight control system, and I wouldn't have thought they'd do that half way through the type's life.

[Dan Winterland]

That level of re-design would entail some costly recertification. However, I gather the A340-600 had an active rudder control which damps out fuselage flexing. Perhaps this is what the article is referring to.

[145qrh]

A345/6 have FBW rudder.....no manual linkage, was part of design for 345/6, so not a redesign partway thro life.

[Kerosene Kraut]

Didn't they introduce FBW Rudder on the A340-300E sometime ago?

[tired]

145qrh - I stand corrected, you're right! -300 rudder is mechanical, -600 is FBW.

I think I need a Tech Refresher. :(

[LLuke]

This FBW rudder will be introduced on other models/versions as well (e.g. A330). Airbus represents it as a feature/improvement over the previous design.

[Sky Wave]

Thanks for the responses

I understood that one of the last fallbacks on the bus if you lost everything was to use the manual pitch trim and the manual rudder to give you some form of control. I assume they consider total loss of power and hydraulics totally inconcievable. However what would of happened to the atlantic glider if the rat had failed to deploy?

I may be over estimating how much use the rudder will be in such a situation. I recall from effects of controls lessons that rudder alone causes a spiral dive, but with trim control I guess you can prevent that and make use of the rudder to point the aircraft in roughly the right direction. (towards land for a ditching off the coast if nothing else)

Any thoughts from Bus Drivers