A330 Yaw (dampers)

[FlyingFox 29]

Would the collective PPrune brains trust help me on this one please?

Was on QF777 01/12/03 (A330 operated) and noticed a small yaw oscillation. Regular 2 second duration (yes I timed it, but them I'm curious and thought the more information the better) across each arc. Thought it might just have been me, but a look out the window using the stbd pylon as a refernce against terrain features proved it beyond doubt. Seemed to last the duration of the flight too, although visual conf was a bit difficult over the Bight no surprise.

Fisrt time I've noticed such an occurence and being a humble "Traumahawk" learner, I was curious to know if this is an A330 specific quirk, a yaw damper hiccup or what? Better qaulify that last remark. I'm aware of yaw dampers and their intended purpose, and also aware that symptomatic issues with yaw dampers can vary but not being tech-savvy on the finer points of such things am seeking Pprune assistance.

Any light that anyone can shed on this for me would be much appreciated.

Cheers
El Fox

[Volume]

You probably noticed the combined roll and yaw oscilation, better known as ´dutch roll´. (can any ppruner tell me where this name comes from ?) 0.5 Hz (2 Seconds duration) sounds quite right. The effect increases with stability, so the more wingsweep and the more (effective) dihedral, the worse. As T-tails also increase the effective dihedral, lot´s of planes use anhedral to compensate for this (most russian T-tail-jets, BAE 146, C-17, C-5...).
Normally the main function of the yaw damper is to cancel this oscilation out, so maybe the yaw damper was inop that flight ?
I´ve never been on a 330, so I don´t know if it is normal to have a slight dutch roll, which only few passengers notice. On the A340-300 I didn´t notice anything.
On the Canadair CRJ-100 and -200 the dutch roll is very claerly noticable, while on the -700 it is much less.

[Bre901]

FF, you are more lucky than me.
I posted a similar question in Tech Log some weeks ago (http://www.pprune.org/forums/showthread.php?s=&threadid=108769) but did not get any answer. Looks very similar.

[Faire d'income]

AFAIK the A330 can despatch under Mel without a yaw damper. This obviously would leave it prone to Dutch roll.

[FlyingFox 29]

Thanks for the information. Makes sense to me now.

Bre901: Sorry to see your question unanswered, hope this helped.

Cheers
El Fox