Airworthiness Directives; The Boeing Company Airplanes

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-8 series airplanes. This AD requires a detailed inspection for correct installation of the flex hose clamp of the occupant backup air supply and a general visual inspection for damage of the flex hose, and related investigative and corrective actions if necessary. This AD was prompted by a report indicating that flex hoses of the occupant backup air supply were found disconnected from the adjacent fiberglass duct on two airplanes. We are issuing this AD to detect and correct an incorrect clamp installation on the inboard end of the flex hose, which allows the flex hose to slowly become disconnected from the adjacent fiberglass duct, and damage to the hose. This condition, in conjunction with a cargo fire event, can potentially lead to decreased airflow to the main deck, possibly resulting in smoke and/ or toxic fumes penetrating into the main deck passenger compartment, which could result in injury to the passengers or cabin crew.