PERIODIC INSPECTIONS

Daily, weekly, biweekly, and monthly inspections are required. Detailed instructions are outlined in the NAVAIR 13-1-6.4 and the Aircrew Survival Equipmentman 3 & 2, Volume 2.

As you read this chapter, you will notice that we use References such as F, 19, E, and so forth. These reference numbers and letters are found in figure 2-1. Also remember that the 1172AS100 test stand is a modified version of the old 62A116E1 test stand; so don't get them confused.

TROUBLESHOOTING THE 1172AS100 TEST STAND FOR LEAKS

As you have already read, leaks will probably cause you the most problems in troubleshooting. Locating a leak in one system is easier than random troubleshooting all systems for a leak. Nine different systems are incorporated within the 1172AS100 oxygen system component test stand. Some of the systems are interconnected and used simultaneously with other systems; therefore, you must be familiar with each system.

A schematic is provided to assist you in analyzing each system as we cover it. The heavy black lines on each schematic depict that particular system. A few symbols are used on the schematics to identify various test stand components. Figure 2-2 is a list of these symbols.

NOTE: To properly perform the leak checks of the different systems, you must perform each test in sequence or your test stand will not be properly set up for your next test.

SAFETY PRECAUTIONS

Before you attempt to operate the test stand, review the following safety precautions. These safety precautions must be observed before, during, and after the test stand operation.

1. Be sure you secure the test stand properly before opening the supply cylinder valve. Position the high-pressure regulator (Q) to LOAD then to VENT; ensure the low-pressure regulator (N) is backed out and the other valves turned fully to the right.

2. Keep the chamber door closed whenever possible.

3. Keep the test stand doors closed at all times.

4. Keep the test stand work tray closed when it is not in use.

5. Check the pump lubricant prior to turning the pump on.

6. Keep your hands and head clear of belts and pulleys while checking lubricant level.

7. Be sure the test stand is properly grounded (refer to Support Equipment Change 1223).

7A. (1172AS100 ONLY) Be sure the test stand is properly grounded using the grounding lug.

8. Never use regulated high pressure and regulated low pressure together.

9. When the oxygen monitor alarm sounds, leave the room.

10. Do not panic when the test stand malfunctions.

11. When you use nitrogen, be sure the room is well ventilated.

12. Use the proper tools for the job you are performing.

13. Avoid breathing pump lubricant and oxygen cleaning compound vapors; avoid lubricant and compound contact with skin or clothing.

14. Avoid breathing mercury vapors; avoid mercury contact with skin or clothing.

15. Secure the test stand completely after use.

16. Never leave test stand unattended while pump is running.

17. When you transport a cylinder, be sure the protective cap is on the cylinder.

SUPPLY NITROGEN SYSTEM

This system supplies a constant source of nitrogen pressure to the other systems within the test stand. It is tested for leaks during the outward leakage test. This test is performed

Figure 2-2.\Test stand schematic symbols.

weekly. In the schematic in figure 2-3, the nitrogen

( N2) supply cylinder is located on the right side of the test stand and is connected to the N 2 input connector. When you open the supply cylinder valve, nitrogen flows to the high-pressure regulator (Q) and the low-pressure regulator (N).

PRESSURIZING THE SUPPLY NITROGEN SYSTEM

The pressure in the supply cylinder is indicated on the supply pressure gage (9). (This gage also tells you when your supply cylinders need replacing.) If you secure all the other valves on the test stand, the system should have no leaks beyond this point. To test for leakage, read the pressure on the supply pressure gage and wait 2 minutes. No drop in pressure should be indicated. At this point, you should leave all valves and connections in their present position. Your supply nitrogen system is pressurized, and you are setup to proceed to the leakage test for the next system.