As about 3 of us are trying to say - this is a fault, supposedly fixed.
Some links from "Just the fax maam":
Honk Kong Dragon Airlines, 1994, mad roll oscillations:
https://aviation-safety.net/wikibase/wiki.php?id=140547
http://ebook.lib.hku.hk/HKG/B35840213.pdf (full report)
Air Canada, 2002:
http://www.bst-tsb.gc.ca/eng/rapport...6/a02o0406.pdf