Action
Final rule.
Summary
We are adopting a new airworthiness directive (AD) for the products listed above. This AD requires repetitive inspections for any damage of the lower surface of the center wing box, and corrective actions if necessary. This AD was prompted by reports of fatigue cracks of the lower surface of the center wing box. We are issuing this AD to detect and correct such cracks, which could result in the structural failure of the wings.