Action
Final rule.
Summary
We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-400, -400D, and -400F series airplanes. This AD was prompted by widespread corrosion damage that was found on the skin inner surface along the upper bulkhead at certain stations between certain stringers. This AD requires repetitive inspections of the fuselage crown skin inner surface, and related investigative and corrective actions if necessary. This AD also allows for terminating actions for the repetitive inspections. We are issuing this AD to address the unsafe condition on these products.