Airworthiness Directives; Boeing Model 747-100B SUD, -200B, -300, -400, and -400D Series Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 747-100B SUD, -200B, -300, -400, and -400D series airplanes. This AD requires repetitive inspections for cracking in fuselage stringers 8L, 8R, 10L, and 10R at body stations 460, 480, and 500 frame locations; and repair if necessary. This AD is prompted by findings of cracking in fuselage stringers 8L, 8R, 10L, and 10R at body stations 460, 480, and 500 frame locations. We are issuing this AD to detect and correct fatigue cracking in certain fuselage stringers, which, if left undetected, could result in fuselage skin cracking that reduces the structural integrity of the skin panel, and consequent rapid depressurization of the airplane.