Airworthiness Directives; Boeing Model 757 Airplanes

We are adopting a new airworthiness directive (AD) for certain Boeing Model 757 airplanes. This AD requires an inspection to determine the manufacturer and manufacture date of the oxygen masks in the passenger service units and the lavatory and attendant box assemblies, and corrective action if necessary. This AD results from a report that several passenger masks 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 passenger oxygen masks from fracturing and separating, which could inhibit oxygen flow to the masks and consequently result in exposure of the passengers and cabin attendants to hypoxia following a depressurization event.