A hat-stringer assembly for an aircraft comprises a hat stringer with a first hat-stringer leg, a second hat-stringer leg, a first hat-stringer sidewall, a connecting wall, a second hat-stringer sidewall, and a ventilation opening, extending through the connecting wall. The hat stringer assembly also comprises a fitting, comprising a first channel member in contact with the first hat-stringer sidewall and the first hat-stringer leg. The fitting also comprises a second channel member in contact with the second hat-stringer sidewall and the second hat-stringer leg. The fitting further comprises a web cap, in contact with the first channel member and the second channel member. The web cap comprises a web-cap opening, which is in fluidic communication with the ventilation opening.