AIRCRAFT PANEL-MOUNTED REGULATORS

Table 12-2.Troubleshooting (Pressure Breathing Test)

TURNAROUND/PREFLIGHT/ POSTFLIGHT/TRANSFER INSPECTIONS

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2. Using LOW PRESS. REGULATOR (N), adjust the inlet pressure to 90 psig. Close OUT- PUT valve (C). 3. Read the PRESS/SUCTION manometer (4). The reading must be between 0.50 and 3.5 in H₂O. Enter this reading in the appropriate block of the performance test sheet. 4. Adjust OUTPUT valve (C) to a flow of 100 lpm and read the PRESS/SUCTION manometer (4). The reading must also be between 0.50 and 3.5 in H₂O. Enter this reading on the test sheet also. 5. Increase the altitude to 43,000 feet, as shown on the HIGH RANGE ALTM. (12), and repeat steps 1 through 3. The readings on PRESS/SUCTION manometer (4) must be between 9.2 and 12.5 in H₂O. 6. Increase the altitude to 50,000 feet. The readings must be between 14.0 and 18.0 in H₂O at this altitude. 7. After the completion of this test, leave OUTPUT valve (C) slightly open, and open CHAMBER BLEED valve (K) and return to sea level. 8. Open the chamber door and close valve (C). Turn off the vacuum pump. 9. Turn ON/OFF valve (L) to OFF, and remove the regulator from the test stand. 10. Close the N₂supply cylinder and, using LOW PRESS. REGULATOR (N) and SYSTEM BLEED valve (S), relieve all the pressure in the test stand. Secure all the test stand valves. 11. If the aneroid should need adjusting, loosen the aneroid lockscrew using a .035 Allen wrench and adjust the aneroid assembly using re- taining pliers in accordance with the pressure breathing test troubleshooting table 12-2. NOTE: Remember we are discussing the model 29267-A1 regulator only. For other models of the CRU-79/P miniature regulator, you must refer to the NAVAIR 13-1-6.4 manual. After the completion of all the tests, you must purge the regulator with aviator’s breathing oxygen for 1 to 3 minutes at 90 psig to the regulator inlet. WARNING NEVER BLOCK THE OUTLET OF THE MINIATURE REGULATOR WHILE PRESSURE IS APPLIED TO THE INLET. THIS WILL SERIOUSLY DAMAGE THE REGULATOR. After completion of the oxygen purge, place the regulator in a plastic bag for storage. AIRCRAFT PANEL-MOUNTED REGULATORS The MD-1, CRU-52/A, CRU-54/A, CRU- 55/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). 12-6

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