Summary
We propose to adopt a new airworthiness directive (AD) for 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, 747SR, and 747SP series airplanes. This proposed AD was prompted by reports of cracks at the lower forward corner of the main entry door (MED) 1 cutout. This proposed AD would require repetitive inspections of the MED door 1 for cracking, and repair if necessary. This proposed AD also provides optional terminating modification; and would require post- repair or post-modification inspections for cracking, and corrective actions if necessary. We are proposing this AD to detect and correct skin cracking, which can become large and could adversely affect the structural integrity of the airplane.