CHAPTER 4 OXYGEN SYSTEMS

CHAPTER 4 OXYGEN SYSTEMS Terminal Objective: Upon completion of this chapter, you will be able to recognize the importance, characteristics, and uses of oxygen and identify oxygen systems, components, and their functions. A dependable supply of oxygen is an essential element for the sustainment of life. Oxygen systems aboard naval aircraft sustain the lives of the pilot and aircrew so they can perform their missions. AME personnel service and maintain aircraft oxygen systems. Therefore, it is very important that AME personnel understand how and why oxygen systems function as they do. This chapter provides an overview of the operating characteristics and maintenance requirements for several specific aircraft oxygen systems, stressing safety and the use of the applicable Maintenance Instructions Manual (MIM). IMPORTANCE OF OXYGEN Learning Objective: Recognize the impor- tance of oxygen to include types, characteristics, and the effects of a lack of oxygen. No one can live without sufficient quantities of food, water, and oxygen. Of the three, oxygen is by far the most urgently needed. If necessary, a well-nourished person can go without food for many days or weeks, living on what is stored in the body. The need for water is more immediate but still will not become critical for several days. The supply of oxygen in the body is limited to a few minutes. When that supply is exhausted, death is inevitable. Oxygen starvation affects a pilot or air- crewman in much the same way that it affects an aircraft engine. Both the body and the engine require oxygen for the burning of fuel. An engine designed for low-altitude operation loses power and performs poorly at high altitudes. High- altitude operation demands a means of supplying air at higher pressure to give the engine enough oxygen for the combustion of fuel. A super- charger or compressor satisfies the engines demands. What about the demands of the human body? The combustion of fuel in the human body is the source of energy for everything the aviator is required to do with muscles, eyes, and brain. As the aircraft climbs, the amount of oxygen per unit of volume of air decreases, and the aviator’s oxygen intake is reduced. Unless the aviator breathes additional oxygen, the eyes, brain, and muscles begin to fail. The body is designed for low-altitude operation and will not give satisfactory performance unless it is supplied the full amount of oxygen that it requires. Like the engine, the body requires a means of having this oxygen supplied to it in greater amounts or under greater pressure. This need is satisfied by use of supplemental oxygen supplied directly to the respiratory system through an oxygen mask, and by pressurizing the aircraft to a pressure equivalent to that at normal safe-breathing altitudes, or both. For purposes of illustration, an aviator’s lungs are like a bag of air since the air in the lungs behaves in the same way. If an open bag is placed in an aircraft at sea level, air will escape from it continuously as the aircraft ascends. The air pressure at 18,000 feet is only half that at sea level; therefore, at 18,000 feet the bag will be subjected to only half the atmospheric pressure it was subjected to at sea level. For this reason, it will contain only half the oxygen molecules it had when on” the ground. In like fashion, an aviator’s lungs contain less and less air as he/she ascends and correspondingly less oxygen. Thus, the use of supplemental oxygen is necessary on high- altitude flights. 4-1