Engine Anti-Ice System Flashcards
Engine and inlet anti-ice components
(1) Engine anti-ice start/bleed valve (mounted on the bottom of the compressor section)
(2) Inlet anti-ice valve
(3) Inlet thermal switch (engine inlet cowling)
How does the engine and inlet anti-ice system work
Hot air flow for anti-icing is distributed through two solenoid-operated air valves. Valves are held closed ELECTRICALLY by the engine anti-ice and deice master switches. When valve is deenergized bleed air is routed to a separate modulating balbe in the engine inlet. When deice master is On/Auto, both solenoid valves are controlled by the ice detector
Three ways to anti-ice engine
1) Vent bleed air into engine swirl vanes and IGVs by the engine anti-ice/start bleed valve
2) Vent bleed air into the airframe engine inlet by the engine inlet anti-ice valve.
3) continuously pump engine oil through scroll vanes
Describe engine anti-ice/start bleed valve
5th stage bleed air to engine with anti-ice on and opens during engine starts.
How can you diagnose a malfunctioning anti-ice/start bleed valve
1) ENG ANTI-ICE (advisory) with above 90% Ng or 94% Ng with OAT 15 or greater
2) No illumination of ENG ANTI-ICE when Ng drops below 88%
3) No illumination of ENG ANTI-ICE with the switch selected on
4) No rise in TFT with switch on
Describe the conditions necessary for a flame out
Temporary hangup of VG system may cause a flameout with low collective settings (autos/quickstops). HMU schedules max fuel flow to VG actuator to release hangup condition. During minimum fuel flow regimes this diversion might be enough to flameout the engine.
How much is TQ reduced with ENG ANTI-ICE ON
18%
Where is the inlet anti-ice valve?
The inlet anti-ice valve is a solenoid-actuated, modulating valve in the engine inlet cowling.
Where does the air come from for inlet anti-ice
Compressor air is routed, through the solenoid actuated inlet anti-ice valve, to the inlet cowling and fairing.
How do the Freon bellows operate
1) Less than 4 C valve open
2) Between 4c and 13C the valve begins closing at 4 and is completely closed by 13C
3) Above 13C, the valve is close and the inlet anti-ice will extinguish once inlet temp is blow 93C
How does oil circulation in the scroll vanes anti-ice
It mainly provides cooling for the hot oil and anti0ice for the main frame. The heated air does not enter the compressor section but is vented overboard through the IPS blower.
