As a part of the blade folding operation, the rotor brake applies manually or automatically. The system is shown in figure 10-11. It consists of a rotor brake assembly, panel package, accumulator, master cylinder, pressure gauge, check valves, and pressure switches.

The rotor brake assembly is comparable to the single disc wheel brake in its design and operation. Hydraulic actuation of the brake may be made manually by using the rotor brake master cylinder located in the cockpit. The brake applies automatically during the blade folding operation by the blade positioner control valve. In manual operation, the brake is capable of stopping the rotary-wing head in 14 seconds from 157 rpm. Replace the brake linings when any of the adjusting pins recede into the adjusting nut 1/8 inch. Replace lock screws and worn parts each time linings are replaced.

This package consists of an accumulator, relief valve, pressure reducer, and a shuttle valve. The package receives hydraulic pressure from the master brake cylinder during manual operation. It receives pressure from the automatic blade folding system during automatic operation. When the master brake cylinder handle is in the OFF or DETENT position, the master cylinder vents to the utility fluid tank. Movement of the master brake cylinder handle blocks

Figure 10-11.Rotor brake and system schematic.

the vent and builds up brake pressure. When the pressure increases beyond 200 psi, the shuttle valve in the panel package shifts. Pressure is sent to the rotor brake and blocks pressure from the automatic blade folding system. The panel package accumulator reduces minor pressure surges during manual and automatic operation. The accumulator maintains a steady pressure to the brake. The relief valve relieves pressure surges in excess of 600 psi.