CHAPTER 12

OXYGEN-RELATED COMPONENTS

Learning Objective: Upon completion of this chapter, you will be able to identify, maintain, and perform maintenance on oxygen regulators and liquid oxygen converters.

_{Oxygen aircraft. They supply the aircrew member with the} regulators are used in all naval necessary oxygen to perform all flying duties under all kinds of conditions. As a PR, you will maintain, service, and test oxygen regulators and liquid oxygen converters. This chapter will give you a basic idea of how a miniature oxygen regulator functions, as well as a panel-mounted regulator and a liquid oxygen converter. It will also cover some of the maintenance that you must perform. The miniature regulator shown in figure 12-1 is a model 29267-A1, type CRU-79/P, and this model is manufactured by Bendix Aviation Corporation. Other models are manufactured by Clifton Precision, Robert Shaw Controls Company and ARO Corporation, but all are type CRU-79/P. They are designed to regulate 100-percent oxygen to the aircrew member during flight. Table 12-1 contains the leading particulars for the regulator.

The miniature regulator reduces and regulates supply oxygen pressure to provide an adequate amount for breathing under a variety of conditions. It has a safety-pressure feature that automatically maintains a positive pressure in the aircrew members mask of 0.50 to 2.5 inches of water above the surrounding air pressure. (Inches of water is a means of measuring the comparatively low pressure used in testing oxygen regulators.) This positive pressure is maintained at all altitudes up to and including 34,000 feet. Above that altitude, the pressure-breathing feature maintains a positive pressure in the mask of up to 18.0 inches of water at altitudes between 34,000 and 50,000 feet, with the positive pressure increasing in proportion to the altitude. Miniature regulators can be used routinely up to approximately 43,000 feet. However, due to human limitations, miniature regulators should

Figure 12-1.-Miniature oxygen breathing regulator model 29267-A1.

Table 12-1.-Leading Particulars for Miniature Oxygen Breathing-Regulator Type CR79/P

not be used above 43,000 feet except for very short periods.

Miniature regulators are designed for use with the MBU-14 series oxygen mask as part of the oxygen system in all aircraft requiring 100-percent oxygen chest-mounted regulators. Refer to the NAVAIR 13-1-6.7 manual for personal configurations of the MBU-14 series oxygen mask.

MAINTENANCE

Maintenance of the type CRU-79/P regulator is limited to inspection, testing, adjustment of the pressure breathing aneroid, and tightening of loose screws. Ensure that antiseize tape is used on pipe threads. This section contains only procedural steps necessary to meet these requirements.

NOTE: Upon completion of any maintenance action (for example, inspection, adjustment, modifications, etc.), be sure to complete the required maintenance data collection system forms.

If the regulator fails any inspection or testing requirements, it must be disposed of in accordance with any local directives and replaced with a ready for issue (RFI) component.

The miniature regulator will remain in service as long as it continues to function correctly and does not require other than authorized adjustment.

Procedural steps outlined in this section are listed under the inspection cycle in which they are required, and in the sequence in which they normally occur.