FliFast

I have not flown the Airbus, and if I may ask:

Is it possible the speed sensing system of the airplane (pitots, air data computer, etc) malfunctioned and the airplane's rudder went from low-throw to high throw ?

Thanks in advance.

FF

Dashdog

This is nothing but pure speculation, and fodder for future lawsuits against the manufacturer. This is an aircraft with an excellent safety record. There has been very little factual information released about the recovery effort so far- probably because there is very little actual information to report, rather than some already developed conspiracy between Air France, Airbus, the French Government ect. Put your tin-foil hats away people.

If the boxes are ever found, maybe that will provide some useful information- or at least some better material for amateur speculation.

ZDub

http://www.ntsb.gov/ntsb/GenPDF.asp?...02MA001&rpt=fi - Hmmmm....

tomgoodman

I'm not familiar with the Airbus rudder limiter, but he 767 has a component called the "Rudder Ratio Changer". If it fails, you get an EICAS message and the left hydraulic system rudder actuator is automatically depressurized.

newKnow

Nevermind.....

alvrb211

Quote:

Originally Posted by PILOTGUY

This is true, but the 737 entire vert. assembly did not break of the aircraft. That was due to a PCU servo value that jammed, not the design of vert stab unit itself.

Interesting viewpoint!

Do you recall what happened when hundreds of innocent people died as a result of Boeing's "Highly unusual" rudder design?

I'll tell you. Not mutch!


If this is indeed an "Airbus rudder issue", I hope they take a lot more action than Boeing did after they designed and delivered disaster!


This isn't about national pride! This is about the lives of innocent people!


Al

LivingInMEM

I talked to a mechanic that is quite familiar with Airbus products. He mentioned that there is a problem with skydrol/hydraulic fluid leaking from rudder actuators and causing eventual delamination.

As for the 737 vs Airbus thing, I'll point out that the 737 hardover rudder resulted in a loss of control and not a structural failure. The 737 hardovers appeared to happen at lower airspeeds, but I wouldn't automatically assume that a structural failure would have occurred had it happened at higher airspeeds.

To bring the American Airlines into the proper reference - the airspeed was a maximum of 251 knots, the rudder pedal traveled a maximum of 2.4 inches, the rudder traveled a maximum of 11 to 12 degrees, and the lateral load factor increased 0.2 g's. It's all in the NTSB report found here: http://www.ntsb.gov/publictn/2004/AAR0404.pdf. I know what the standard thoughts are on the factors surrounding the loss of that vert stab, but I don't know anyone who would have thought that those numbers at that airspeed should result in any sort of structural failure.

Sniper

Anything is possible. Is it more than a remote possibility - IMO, yes, though this board conjectured for almost a week about a tail stall due to excessive iceing being a factor in the Colgan crash, only to hear NTSB testimony that it is virtually impossible to tail stall a Q400, so . . .

According to Aviation Week and Space Technology:
I'm not typed on the 330, but am on other Airbus products. How it works (or is supposed to) on other Airbus products is, The FACs (Flight Augmentation Computers) control the rudder travel limit. If both FACs fail, the rudder travel is limited to 'low throw' by default, and goes to 'high throw' with the extension of slats. Rudder is a very primary control in Airbus logic, and the worst case flight control loss (other than full lose, of course) is 'Mechanical Backup', which uses the rudder for lateral control. Though this requires hydraulic power, the link itself is, as you can assume by 'Mechanical Backup", directly mechanical (as is the link between the stab trim wheel and the horizontal stab).

Rudder travel linked to speed, but accurate speed indications lost.
Rudder travel linked to rudder travel limiter, but limiter lost.
Rudder doesn't move much if AP is on, but AP was disengaged.
Rudder travel now dependent on pilot inputs, and pilot is flying around turbulence and thunderstorms with not much horizon reference (dark, mid atlantic), suspect speed indications, and @ higher speed, as well as many bells and whistles going off.

IMO the situation certainly presents the possibility that the rudder could be manually over-controlled, similar to the AA accident (as 'LivingInMEM' wrote, the amount of input to get to an 'over control' situation is much more minute than most would suspect, or at least was in the AA accident), given what the ACAR's messages indicate.

--
If I am in the wrong, please feel free to correct my post. I'm no expert, just an interested observer, wondering, like many others, how a vertical stab escaped this disaster rather unscathed when the rest of the aircraft did not, and if anything can be learned from this.

Sniper

First time I've seen it: here

alvrb211

It was an unusually poor design that brought the 737's down!


Al