AD FAA-2009-0795

We are adopting a new airworthiness directive (AD) for certain Model 757 airplanes. This AD requires inspecting to verify the part number of the low-pressure flex-hoses of the flightcrew and supernumerary oxygen system installed under the oxygen mask stowage box at a flightcrew and supernumerary oxygen mask location, and replacing with a new non-conductive low-pressure flex-hose of the oxygen system if necessary. This AD results from reports of a low-pressure flex-hose of a flightcrew oxygen system that burned through due to inadvertent electrical current from a short circuit in an adjacent audio select panel. We are issuing this AD to prevent inadvertent electrical current, which can cause the low-pressure flex-hose of a flightcrew or supernumerary oxygen system to melt or burn, resulting in oxygen system leakage and smoke or fire.