Airworthiness Directives; The Boeing Company Model 747-200B, -300, -400, -400D, and -400F Series Airplanes Powered by Pratt and Whitney 4000 or General Electric CF6-80C2 Series Engines

요약

We are adopting a new airworthiness directive (AD) for the products listed above. This AD requires an inspection to determine the part number of the mid-pivot access door and to determine if the correct door is installed, and the installation of a marker on the mid- pivot access door, and if necessary, repetitive ultrasonic inspections for cracking of the mid-pivot bolt assembly and eventual replacement of the mid-pivot bolt assembly. This AD was prompted by a report that the left and right access doors of the spring beam mid-pivot bolt assembly for the No. 1 strut were inadvertently installed in the incorrect position during strut modification. We are issuing this AD to detect and correct incorrectly installed mid-pivot bolt assemblies on the spring beam on the outboard struts. Incorrectly installed bolt assemblies could lead to fatigue cracking and consequent fracturing of the mid-pivot bolt assembly, which could lead to loss of the spring beam load path and the possible separation of a strut and engine from the airplane during flight.