Engine and Inlet Anti-Ice System

Question 1

The engine anti-ice/ start bleed valve remains open below approximately _____ percent Ng to prevent_______.

Answer 1

90

compressor instability during starts

Question 2

A malfunctioning anti-ice/start bleed valve is indicated by any one of the following:

Answer 2

1. Illumination of the ENG ANTI-ICE ON advisory light with above 90 percent Ng or above 94 percent Ng if OAT is 15 degrees C or greater.
2. No illumination of the ENG ANTI-ICE ON advisory light when Ng drops below approximately 88 percent Ng. (Ng may vary on a sliding scale depending on OAT.)
3. No illumination of the ENG ANTI-ICE ON advisory light when the ENG ANTI-ICE switch i selected ON>
4. No rise in TGT when ENG ANTI-ICE switch is selected ON.

Note: With ENG ANTI-ICE ON, max torque available is reduced up to 18 percent per engine.

Question 3

The inlet anti-ice valve is a ________ valve located in the engine inlet cowling.

Answer 3

solenoid-actuated, modulating

Question 4

The inlet thermal switch, mounted inside the engine inlet cowling, senses the air temperature inside the cowling. #1/#2 inlet thermal switches illuminate when bleed air heats the engine inlet to approximately _____.

Answer 4

93 degrees C

Question 5

Though the inlet anti-ice valve may be deenergized open, with removal of dc primary bus power from the valve solenoid, the release of fifth stage compressor bleed air into the engine inlet cowling and inlet fairing is ultimately controlled by _______, which react only to the _____.

Answer 5

freon filled bellows, ambient temperature

Question 6

The freon filled bellows operate as follows:

Answer 6

1. Less than 4 degrees C, the valve is ope and INLET ANTI_ICE ON advisories appear when inlet temperature reaches 93 degrees C
2. Between 4 and 13 degrees C, the valve is controlled by a temperature-compensating Freon-filled bellows. The bellows begins closing the valve when the OAT reaches 4 degrees C and should be completely closed by 13 degrees C.
3. Above 13 degrees C, the valve is cllosed and the INLET ANTI-ICE ON advisories will extinguish when inlet coling temp drops below 93 degrees C.

Question 7

Warning: Illumination of the inlet anti-ice on light when OAT is 13 degrees C is an indication of______. Resultant loss of power could be a maximum of _____ percent when the engine anti-ice system is activated.

Answer 7

a faulty inlet anti-ice modulating valve

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