More fireproofing was added after a fire in February 1975 that spread to six floors before being extinguished. After the 1993 bombing, inspections found fireproofing to be deficient. The Port Authority was in the process of replacing it, but replacement had been completed on only 18 floors in the North Tower, including all the floors affected by the aircraft impact and fires on September 11, and on 13 floors in the South Tower, although only three of these floors (77, 78, and 85) were directly affected by the aircraft impact.