Summary
We propose to supersede Airworthiness Directive (AD) 2005-01- 09, which applies to certain The Boeing Company Model 747-100, 747- 100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, and 747SR series airplanes. AD 2005-01-09 requires a one-time detailed inspection for discrepancies of the frame web and inner chords on the forward edge frame of the number 5 main entry door cutout, and corrective action if necessary. Since we issued AD 2005-01- 09, additional cracking was found in the same area after completion of the one-time detailed inspection. This proposed AD would add repetitive high frequency eddy current inspections for cracking of the frame inner chords (forward and aft), and corrective action if necessary. We are proposing this AD to detect and correct discrepancies of the frame web and inner chords, which could result in cracking, subsequent severing of the frame, and consequent rapid depressurization of the airplane.