Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747- 200C, 747-200F, 747-300, 747SR, and 747SP series airplanes. This proposed AD would require doing a one-time high-frequency eddy current inspection and repetitive detailed inspections for cracks in the frame web of main entry door number 1; and repairing the door frame web if necessary. This proposed AD would also provide for optional terminating action for the repetitive inspections. This proposed AD is prompted by reports of cracking at the upper aft corner of the cutout for main entry door number 1 in the station 488 frame web. We are proposing this AD to detect and correct cracks in the frame web. These cracks could cause the frame to break and lead to rapid decompression of the airplane.