AD FAA-2010-0045

We are adopting a new airworthiness directive (AD) for certain Model 747 airplanes. This AD requires inspecting to verify the part number of the low-pressure flex-hoses of the crew oxygen system installed under the oxygen mask stowage boxes in the flight deck, and replacing the flex-hose with a new non-conductive low-pressure flex- hose if necessary. This AD results from reports of low-pressure flex- hoses of the crew oxygen system that burned through due to inadvertent electrical current from a short circuit in the audio select panel. We are issuing this AD to prevent inadvertent electrical current, which can cause the low-pressure flex-hoses of the crew oxygen system to melt or burn, causing oxygen system leakage and smoke or fire.