Airworthiness Directives; Boeing Model 747-200F and -200C Series Airplanes

This amendment adopts a new airworthiness directive (AD) that is applicable to all Boeing Model 747-200F and -200C series airplanes. This action requires repetitive inspections or a one-time inspection to detect cracking of certain areas of the upper deck floor beams; and corrective actions, if necessary. This amendment is prompted by reports indicating that fatigue cracks were found in the upper chord and web of upper deck floor beams. The actions specified in this AD are intended to prevent such fatigue cracking and the resultant failure of such floor beams. Failure of the floor beam could result in damage to critical flight control cables and wire bundles that pass through the floor beam, and consequent reduced controllability of the airplane; failure of the floor beam also could result in the failure of the adjacent fuselage frames and skin, and consequent rapid decompression of the airplane.