Provides guidance material to manufacturers and operators of transport category airplanes for use in developing a continuing structural integrity program to ensure safe operation of older airplanes throughout their operational lives. This guidance material applies to large transport airplanes which were certified under the fail-safe and fatigue requirements of Civil Air Regulations (CAR) 4b o 14 CFR part 25 of the Federal Aviation Regulations (FAR), prior to Amendment 25-45, and which have a maximum gross weight greater than 75,000 pounds. Guidance material on this subject for other transports is provided in AC 91-60. The procedures set forth by this AC are applicable to the large transport category airplanes operated under Subpart D of part 91, and parts 121 and 125.