ice protection

The window heat control switches control heating to the:

Forward windshield only — The electrically heated window system is intended to protect the forward windshields used for primary outside visibility; the other flight deck windows are not controlled by these switches. [Ref: FCOM 3.20.4, 3.10.3]

Probe heat supplies heat to:

4 pitot-static probes; 2 angle of attack probes (engine operating); 2 TAT — Probe heat protects the air-data sensors that are vulnerable to icing. Pitot-static and TAT probes require heat for accurate pressure/temperature sensing, while AOA probe heating is tied to engine operation. [Ref: FCOM 3.20.4]

What will happen if the engine 1 nacelle anti-ice switch is ON and the valve remains closed?

Anti-ice valve remains closed; EICAS Nacelle Anti ice Valve 1 message; valve light illuminates. — With the switch commanding anti-ice ON, a valve that stays closed creates a commanded-versus-actual position disagreement. The system therefore provides both a valve indication and an EICAS advisory. [Ref: FCOM 3.20.1]

When do the TAT probes receive anti-icing protection?

In flight — TAT probes are heated in flight to prevent icing from corrupting total-air-temperature data; their ground heating logic is restricted to avoid unnecessary heating while parked. [Ref: FCOM 3.20.4]

What does the EICAS advisory message HEAT P/S F/O mean?

Heater on the FO pitot-static side is not powered — The HEAT P/S F/O advisory identifies loss of electrical power to the First Officer pitot-static heating circuit, meaning the affected probe heating is not available as commanded. [Ref: FCOM 3.30.1]

What happens when the First Officer's windshield air switch is ON?

Anti-fogging air flow from the flight deck conditioned air supply to right windshield — The windshield-air system uses conditioned flight deck air as an anti-fogging layer across the inside surface of the selected windshield; the FO switch controls the right side. [Ref: FCOM 3.20.4]

If the EICAS message HEAT R TAT is displayed on the ground, power is being applied to the right TAT probe. True or False?

True — On the ground, a HEAT R TAT message can indicate that the right TAT probe is being heated when ground logic normally expects it not to be. That is why the statement is true even though the same message in flight can indicate a heat failure. [Ref: FCOM 3.30.1]

When should wing anti-ice be used on the ground?

Never — Wing anti-ice is an in-flight pneumatic system. Ground use is avoided because heating the wing while stationary can create excessive local temperatures and is outside the normal operating logic. [Ref: FCOM SP.16.7]

What does the EICAS advisory message HEAT L TAT mean?

L TAT probe heat is failed or on the ground TAT probe is heated. — The advisory indicates an abnormal condition of the left TAT heating system: either the probe is not being heated when it should be in flight, or it is being heated on the ground when it normally should not be. [Ref: FCOM 3.30.1]

Which is true with the nacelle anti-ice switches ON?

All of these: nacelle anti-icing valves open; green EICAS nacelle anti-ice message; approach idle. — Selecting nacelle anti-ice commands hot bleed air through the nacelle anti-ice valves. Engine control logic also raises minimum idle to approach idle so sufficient bleed-air pressure is maintained. [Ref: FCOM 3.20.1]

What is required to prevent wing damage after landing, with the wing anti-ice switch OFF, and the EICAS WAI VALVE RIGHT message displayed?

Bleed duct on respective side needs to be isolated. ENGINE BLEED switch OFF (affected side), ISLN valve switch OFF (right). — A wing anti-ice valve that remains open after landing can continue feeding hot bleed air into the wing. Isolating the affected bleed duct removes that heat source and prevents structural overheating. [Ref: QRH page 119]

Heat for which windows is controlled by the window heat switches?

Front only (Right or Left - CAPT or FO switches) — The CAPT and F/O window-heat switches are side-specific controls for the two forward windshields, not general controls for all cockpit windows. [Ref: FCOM 3.20.4]

What does the EICAS message HEAT followed by the name of the probe mean?

Probe heat has failed; unpowered probe. — A HEAT message followed by a probe identifier points to loss of the commanded heating function for that specific probe, helping the crew identify which air-data sensor is no longer protected from icing. [Ref: FCOM 3.30.1]

When is the EICAS advisory message WAI VALVE LEFT displayed?

Valve is not in the commanded position. — The message is based on valve position disagreement: the wing anti-ice valve has not reached the position commanded by the system, whether the command was to open or to close. [Ref: FCOM 3.30.1]