Identification & Location
The Hot Air Valve is mounted to the impeller housing assembly and controls the flow of anti-icing air to the inlet housing. This valve, which is electrically controlled, is normally energized, causing the valve to be in a closed position.
When Anti-icing air flows forward through a regulator tube into hollow annulus (port) on top of the inlet housing. This hot air is then circulated through five of the six hollow inlet housing support struts to prevent ice formation in the inlet housing area.
When Anti-icing air is required, the solenoid is de-energized by manually activating a switch in the cockpit, causing the air pressure to open the valve. This allows the hot air to enter the inlet housing through the transfer tube to prevent the formation of ice. The valve design incorporates a fail-safe provision which insures continuous Anti-icing air flow in the event of an electrical failure.
Anti-icing of the 6 o’clock strut area is accomplished by draining hot engine scavenge oil through the strut into the accessory gearbox. Anti-icing air also flows into an annulus in the rear of the inlet housing where it is directed through the hollow inlet guide vanes. This allows exhaust to forward to the Variable Inlet Guide Vane (VIGV) Assembly into the inlet air stream.