I think GB is quite right. Roadrunner, we can often feel the same clunk from the cockpit when the landing gear hydraulics are depressurised by putting the gear lever "off" immediately after the flaps finish retracting. You don't tend to notice it all the time though. Just a quirk of the 767.
I shouldn't speculate I suppose, but at least allow me to apply "Occams Razor": Old aeroplane with known corrosion issues. Hmmmm. Seems like corrosion/fatigue is really the most likely culprit.
The other theories are a bit out of left field (except for the oxy bottle one - certainly a possibility), but everything will be investigated, obviously.
Last edited by DutchRoll; 26th Jul 2008 at 01:37.