Thanks Scott,

Yes- 320.

Just spoke to the bloke who knows about the phenomenon and he said he has seen this before on Glassairs and Lancairs. Non structural as I thought.

I’ll run a monitor on it until February when the annual occurs, and given I’ll be in the US and UK for six weeks the aircraft will not be flying a lot.

I suspect it is sticky noses who wander into the hangar while it is open to the public.

Dom