AD FAA-2011-0139

We are adopting a new airworthiness directive (AD) for the products listed above, except for those that are currently affected by similar action through any of five ADs applicable to Boeing products. This AD requires an inspection/records check to determine the manufacturer and part number of the oxygen mask assemblies installed, an inspection to determine the manufacturing date and modification status if certain oxygen mask assemblies are installed, and corrective action for certain oxygen mask assemblies. This AD was prompted by a report that several oxygen mask assemblies with broken in-line flow indicators were found following a mask deployment. We are issuing this AD to prevent the in-line flow indicators of the oxygen mask assembly from fracturing and separating, which could inhibit oxygen flow to the masks. This condition could consequently result in occupants developing hypoxia following a depressurization event.