The maintenance procedures discussed in this section are general in nature. Consult the applicable MIM prior to performing any maintenance on each specific type of aircraft. Routine maintenance includes servicing of cylinders, checking the system and regulators for

Figure 4-6.- Walkaround oxygen bottle cylinder.

leaks, operationally checking the system, and troubleshooting malfunctions. Malfunctions may become apparent during inspections, testing, or actual use of the oxygen system. The remedies for some malfunctions will be quite obvious, while others may require extensive time and effort to pinpoint the actual cause. The effectiveness of corrective action will be dependent on an accurate diagnosis of the malfunction.

Troubleshooting of the gaseous oxygen system, as with other systems, is the process of locating a malfunctioning component or unit in a system or mechanism. To troubleshoot intelligently, you must be familiar with the system and know the function of each component within the system. You can study the schematic diagrams of the system provided in the MIM to gain a mental picture of the location of each component in relation to other components. By learning to interpret these diagrams, you can save time in isolating malfunctioning components. The sche-matic diagram does not indicate the location of components in the aircraft; however, it will provide the means to trace the oxygen flow from the cylinder through each component to the mask.

Installation diagrams provided in either the MIM or the Illustrated Parts Breakdown (IPB) will assist you in locating the particular component in the aircraft.

The MIMs provide a variety of trouble-shooting charts, which are intended to aid you in discovering the cause of malfunction and its remedy. Table 4-1 illustrates one type of chart. The discrepancy is listed in the first column with

Table 4-1.- Gaseous Oxygen System Troubleshooting

the probable cause in the second and the remedy in the third. The list of probable causes is arranged in the order of probability of occurrence. Some manufacturer's troubleshooting charts or aids may include several sheets, similar to the one illustrated in table 4-2, This sheet gives a step-by- step method to correct known malfunctions. Notice how each step progresses through the system. At each step it indicates a correction procedure; however, if the system checks OK at that point, directions are given to proceed with further logical troubleshooting. In almost all cases, the steps of troubleshooting are arranged to correspond with the steps of the operational 'checkout procedures.