AIRCRAFT PANEL-MOUNTED REGULATORS

The MD-1, CRU-52/A, CRU-54/A, CRU55/A, CRU-57/A, MD2, and CRU-72/A shown in figures 12-3 and 12-4 are panel-mounted, automatic, positive pressure diluter demand-type regulators, and they are used in conjunction with the pressure breathing type oxygen mask. The regulators provide 100-percent oxygen, or an air/oxygen mixture at the correct ratio, depending

Figure 12-3.-Aircraft panel mounted oxygen regulator, MD-1 (low pressure).

Figure 12-4.-Aircraft panel mounted oxygen regulator, MD-2 (high pressure).

on altitude, to the user on demand. The regulators incorporate an emergency pressure control lever. During normal operation, the lever is set in the NORMAL position. A TEST MASK position is provided to test the oxygen supply function of the regulators at low altitudes and at ground level. When in the EMERGENCY position, the regulators deliver 100-percent oxygen to the user at a positive pressure. The EMERGENCY position is used when normal oxygen is suspected of being inadequate.

The regulators are supplied in two basic configurations: low pressure (50 to 500 psig operating pressure range), and high pressure (50 to 2000 psig operating range). Refer to table 12-3 for applicable models and part numbers.

MAINTENANCE

When assigned to an AIMD or a depot-level maintenance activity, you may be involved in making repairs to these regulators. When the cost of repair is more than approximately 75 percent of the cost of the regulator, it is considered beyond economical repair.

TURNAROUND/PREFLIGHT/ POSTFLIGHT/TRANSFER INSPECTIONS

The turn around/preflight/postflight/transfer inspections consist of a visual type inspection performed in conjunction with the aircraft inspection requirements for the aircraft in which

Table 12-3.-Leading Particulars

the regulators preinstalled. Refer to table 12-4 for assistance in troubleshooting. To perform the inspection, visually inspect the following:

1. Electrical performance of panel light.

2. Legibility of all markings.

3. Plastic lighting plate for cracks and discoloration.

4. Low, or improper reading on regulator pressure gauge.

5. Emergency pressure control lever in NORMAL position.

6. Diluter control lever in 100-percent OXYGEN position.

7. Supply control lever in OFF position.

8. Regulator and surrounding area for freedom from dirt and hydrocarbons.

9. Delivery hose and connector for cuts, _{graying, kinking,} hydrocarbons and general condition.

If discrepancies are found or suspected, notify maintenance control.

If a regulator does not pass your inspection and the defect cannot be repaired in the aircraft, remove it and put in a ready for issue (RFI) regulator. Forward the defective regulator to an aircraft intermediate maintenance activity that can fix it.