Summary
The FAA proposes to supersede Airworthiness Directive (AD) 2017-18-05, which applies to all 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. AD 2017-18-05 requires repetitive replacement or inspection of certain fuse pins, and applicable on-condition actions. Since the FAA issued AD 2017-18-05, it has been determined that adding repetitive ultrasonic testing (UT) inspections of the fuse pin of the wing landing gear beam end fitting for any cracking and the option for repetitive replacement of certain corrosion-resistant (stainless) steel (CRES) fuse pins and steel alloy fuse pins is necessary to address the unsafe condition. This proposed AD would continue to require the actions in AD 2017-18-05 and would also require repetitive replacement of certain fuse pins at the wing landing gear beam end fitting, and repetitive inspections of the fuse pin for any cracking and applicable on-condition actions. This proposed AD would also revise the applicability by adding airplanes. The FAA is proposing this AD to address the unsafe condition on these products.