Action
Final rule.
Summary
We are adopting a new airworthiness directive (AD) for certain Model 737-300, -400, -500, -600, -700, and -800 series 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 located within 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.