Summary
We propose to adopt a new airworthiness directive (AD) for The Boeing Company Model 707 airplanes, Model 720 and 720B series airplanes, Model 727 airplanes, and Model 737-100, -200, and -200C series airplanes. This proposed AD was prompted by a report of a fire which originated near the first officer's area and caused extensive damage to the flight deck on a different airplane model. This proposed AD would require replacing the low-pressure oxygen hoses with non-conductive low-pressure oxygen hoses in the flight compartment. We are proposing this AD to prevent inadvertent electrical current from passing through an internal, anti-collapse spring of the low-pressure oxygen hose, which can cause the low-pressure oxygen hose to melt or burn, leading to an oxygen-fed fire and/or smoke in the flight deck.