Aircraft Oxygen Equipment — Page 275, Lesson 350

Right, let's get into the safety side of aircraft oxygen systems. This is the part of the chapter that keeps you alive, so I want you to treat every single line here as a hard rule, not a suggestion. The core message is that oxygen is not a benign gas. It is non-flammable, but it is heavier than air, and it actively supports combustion. That means it doesn't burn itself, but it makes everything else burn far more fiercely than it would in normal air. Any flammable material will burn much more violently in an oxygen-rich atmosphere. So the first rule is obvious: smoking is banned in any oxygen-rich environment, and you must remove all combustible materials from the area where oxygen recharging is taking place. Now, the next hazard is oil and grease. This is critical. No oil or grease may ever come into contact with oxygen. The reason is that there's a real possibility of a severe chemical reaction and spontaneous combustion. So your tools, your protective clothing, everything that touches the system must be completely free of oil and grease. This is why you'll see specific handling rules around oxygen fittings. Third, moisture. Any moisture present will react with gaseous oxygen, and that can cause corrosion inside the system and, importantly, the possibility of valves freezing. You'll also notice the oxygen will probably smell "bad" when it's used, which is a sign of contamination. This is exactly why aircraft must only be replenished with oxygen that is approved for aviation use. Not just any breathing oxygen — aviation-approved oxygen. Fourth, ventilation. During replenishment or maintenance of oxygen systems, the surrounding area must be adequately ventilated. And here's the key reason: remember oxygen is heavier than air. So it will sink and fill low-lying areas — think servicing pits, aircraft bilges, anywhere that's below the general floor level. If you don't ventilate, you're creating a pocket of oxygen-rich air that you can't see. Fifth, lubrication. Only lubricants that are specified in the maintenance manuals may be used. The example given is graphite. So you never grab a general-purpose grease; you use exactly what the manual dictates. Finally, cylinder identification. Oxygen cylinders are identified by their colour. American and European cylinders are green, and British cylinders are black with a white neck. That's a quick visual check you'll do in the field. One more thing to stress: these are the general precautions that apply to all oxygen systems. Specific precautions for individual aircraft types are contained in the appropriate aircraft manual, and as a flight crew member you are expected to familiarize yourself with the safety precautions for the specific type you're operating. So this page is your foundation, but the type manual is your authority. That's the safety picture. Let's move on when you're ready.