Two types of pneumatically operated emergency systems are currently used in naval aircraft. One type consists merely of one or more storage cylinders, a control in the cockpit for releasing the contents of the cylinders, a ground charge valve, and the connecting lines and fittings. This type of system must be serviced with compressed air or nitrogen.

Figure 7-42.Ram air turbine-control system schematic.

 The other type of system in current use has its own compressor and other equipment necessary for maintaining an adequate supply of compressed air during flight. Provision for ground charging this type of system is also provided. In addition to a compressor, the components in this type of system usually include a filter, a pressure regulator, a moisture separator, a relief valve, a chemical drier, and storage cylinder(s).

AIR COMPRESSORS. A typical air com-pressor is shown in figure 7-43. An installation of this type receives its supply of air from the compressor section of the aircraft engine. This air is then compressed further to the required pressure for operating the system. Compressors of this type are capable of maintaining up to and above 3,000 psi pressure during flight.

On some aircraft, the compressor is operated by an electric motor. On others, a hydraulic motor is used to drive the compressor. Compressors must be serviced with oil periodically, as outlined in the aircraft MIM. An oil level sight gauge is provided on the compressor (fig. 7-43).