OK, stop drilling is a good explanation for me but how could you see that?
I assume you're right, up to the point when we can see a better pic.
Fantaman:
Category 1 means that Bulgaria CAA satisfies FAA Category 1 rules (based on ICAO rule, I forgot which number).
It includes both carriers and MROs etc. If this was a crack that would be bad since carrier's maintenance should have catch it.
Cheers,