Airworthiness Directives; Boeing Model 737-300, -400, -500, -600, -700, -800 and -900 Series Airplanes; and Model 757-200 and -300 Series Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 737-300, -400, -500, -600, -700, -800 and -900 series airplanes; and Model 757-200 and -300 series airplanes. This AD requires modifying the activation mechanism in the chemical oxygen generator of each passenger service unit (PSU). This AD results from several reports indicating that some chemical oxygen generators failed to activate during in-flight decompression events. These failures were due to fracture of components between the passenger oxygen mask and the release pin in the oxygen generator. We are issuing this AD to prevent failure of the activation mechanism in the chemical oxygen generator, which could result in the unavailability of supplemental oxygen and possible incapacitation of passengers and cabin crew during an in- flight decompression.