I've noticed a grey line on the flaps of the A319:
What is that?
Aviation Stack Exchange is a question and answer site for aircraft pilots, mechanics, and enthusiasts. It only takes a minute to sign up.Sign up to join this community
You are seeing the steel reinforcing sheet metal at the line where the spoilers rest on the flaps when both are retracted. It is there as a bearing surface since there is some inevitable contact between the spoilers and the top surface of the flap when they are both retracted during flight.