Anti-Ice

Question 1

What is the purpose of the anti-ice system?

Answer 1

Prevent ice on components of the engine inlet section

Question 2

What are the ways to anti-ice the engine? (3)

Answer 2

• Engine anti-ice/start bleed valve
• Scroll Vanes
• Engine inlet anti-ice valve

Question 3

How many solenoid air valves are there?

Answer 3

2

Question 4

What 2 switches control the solenoid air valves?

Answer 4

ENG ANTI-ICE
DE-ICE MASTER

both are held closed electrically

Question 5

What happens when ENG ANTI-ICE ON?

Answer 5

Valve is de-energized open, bleed air is routed to a separate modulating valve in the inlet section

Question 6

What happens if DE-ICE MASTER is ON?

Answer 6

Both solenoids are controlled by the ice detector

Question 7

How does the Scroll Vanes (air/oil cooler) anti-ice?

Answer 7

Continuous circulation of hot oil through the scroll vanes cools the oil and heats up the main frame.

Air is then vented overboard by the IPS and does not proved anti-ice to the air entering the compressor

Question 8

What are the indications of a malfunctioning engine anti-ice valve? (4)

Answer 8

• ENG AINTI-ICE ON above 90 or 94% Ng (OAT above 15 C)
• No ENG ANTI-ICE ON when Ng below 88%
• No ENG ANTI-ICE ON when switch is ON
• No TGT rise (30-100 C) when switch is ON

Question 9

What is the reduction of TRQ available when ENG ANTI-ICE ON?

Answer 9

up to 18% per engine

Question 10

How does the HMU compensate for Variable Geometry hangup at the ENG ANTI-ICE Valve?

Answer 10

When collective is full down, HMU schedules max fuel flow

Question 11

Where is the Inlet Engine Anti-Ice Valve located?

Answer 11

Inlet cowling

Question 12

How does the Inlet Engine Anti-Ice Valve work?

Answer 12

It senses air temp inside the cowling via Freon Bellows

Question 13

When does the #1/#2 INLET ANTI-ICE ON illuminate?

Answer 13

Turns on when bleed air heats the inlet to ~93%

Question 14

Is the Inlet Engine Anti-Ice Valve energized if both ENG ANTI-ICE switches are OFF?

Answer 14

No, because the solenoid is electrically closed

Question 15

If ENG ANTI-ICE switches are OFF and DE-ICE ON, how does Inlet Engine Anti-Ice Valve work?

Answer 15

Freon Bellows work ONLY when ICE DETECTED illuminates

Question 16

If ENG ANTI-ICE switches are ON, how does the Inlet Engine Anti-Ice Valve work?

Answer 16

Uses Freon Bellows that react based on OAT

Question 17

How do the Freon Bellows work?

Answer 17

• Less than 4 C, valve is full open and INLET ANTI-ICE ON when inlet cowling inlet temp above 93 C
• Between 4-13 C, valve is variably controlled
• Above 13 C, valve is full closed and INLET ANTI-ICE ON extinguished when inlet cowling inlet temp below 93 C

Question 18

What is the indication of a malfunctioning Inlet Engine Anti-Ice Valve?

Answer 18

INLET ANTI-ICE ON illuminates when OAT above 13 C

*may lose up to 49% TRQ available and may lead to insufficient power to maintain level flight