Summary
The FAA proposes to adopt a new airworthiness directive (AD) for all The Boeing Company Model 747-100, -100B, -100B SUD, -200B, - 200C, -200F, -300, -400, -400D, -400F, 747SR, and 747SP airplanes. This proposed AD was prompted by reports of cracks found in the front spar shear tie and at the intercostal lug fitting at certain locations. This proposed AD would require repetitive detailed and surface high frequency eddy current (HFEC) inspections of the front spar shear tie and intercostal lug fitting at certain locations for any cracking, and applicable on-condition actions. The FAA is proposing this AD to address the unsafe condition on these products.