RAIN-REMOVAL PRESSURE-REGULATOR SHUTOFF VALVE

electrically actuated and operated. The valve is installed in the hot bleed-air duct in the starboard engine compartment. The valve is controlled by the nosewheel well bleed-air switch on the fuel management panel. When the switch is set to the OFF position, the valve is closed by 115-volt ac power from the bleed-air circuit breaker. When the switch is set to the AUTO position, power is routed to the nosewheel well bleed-air relay. When the windshield switch on the air-conditioning panel is moved to the AIR position, or when left main landing gear weight-on-wheels switch is closed, the relay is activated and the valve opens. If electric power is lost, the valve will remain in the last selected position. The valve has a position indicator that can be viewed with the starboard engine-bay door open. RAIN-REMOVAL PRESSURE-REGULATOR SHUTOFF VALVE.— The rain-removal pres- sure-regulator shutoff valve is a pneumatically operated, solenoid-controlled, 2-inch valve installed in the hot bleed-air duct to the rain- removal nozzle assembly. (See fig. 3-8.) Operation of the valve is controlled by the windshield switch on the air-conditioning control panel. Placing the switch to the AIR position energizes the solenoid of the valve. When the inlet pressure to the valve is between 15 and 50 psi, the valve is fully opened. When it is between 100 and 250 psi, the valve regulates the outlet pressure to the rain-removal nozzle at 75±3.5 psi. By placing the windshield switch to OFF, it de-energizes the solenoid. This causes the valve to close and shuts off the flow of bleed air to the rain-removal nozzle. In the closed position, air from the upstream side of the valve passes through the control air passages to chamber A and leaks past the pilot valve stem to chamber B. With equal pressure on both sides of the large diaphragm, the pressure on the small diaphragm and the spring force on Figure 3-8.-Rain-removal Pressure-regulator shutoff valve. 3-8