Chapter 3 - Anti-Ice, Rain Protection System Flashcards
Quick Look
NAI
When nacelle anti-ice is commanded on, the selected engine igniters operate continuously. In automatice
mode, when ice is detected, bleed air opens the nacelle anti-ice valve and bleed air is supplied to the engine
cowl inlet. When ice is no longer detected, the nacelle anti-ice valve closes and bleed air is no longer supplied
to the engine inlet cowl. In manual mode, when the NACELLE ANTI-ICE switch is ON, bleed air opens the
nacelle anti-ice valve and bleed air is supplied to the engine inlet cowl.
Nacelle Anti-Ice
ON - NAI is on when bleed pressure present
- Continuous ignition is on
Off (No light) - NAI is off
VALVE Light - NAI valve position disagrees with switch position or valve in transit.
NAI Normal Operation
NAI Operation on ground
- Every 30 minutes
- For 30 seconds
- 60% N1
- Turn on after each engine start
NAI Operation in-flight
- All engines if less than 70% N1
- One engine at a time above 70% N1
- Every 10 minutes
- For 10-30 seconds
- Due to ice build up behind the N1 fan
NAI Non-Normal Operations
During normal ops the Pressure Regulating Valve (PRV) opens when NAI is on.
The PRV Closes when:
- Prior or present bleed air overheat
- Start valve not closed
- HP Bleed valve failed open
ANTI-ICE
LIMITATION
Nacelle anti-ice must be ON during all ground and flight operations when icing conditions exist or are anticipated, except when the
temperature is below -40°C OAT.
Icing conditions exist when
- OAT on the ground and for takeoff
- TAT in-flight is 10°C (50°F) or below
- visible moisture in any form
OR
- when operating on ramps, taxiways or runways where surface snow, ice, standing water or slush may be ingested by the engines or freeze on engines, nacelles or engine sensor probes.
Quick Look
WAI
The wing anti-ice system provides bleed air to each wing. When anti-ice is commanded on, a valve opens in
each wing, allowing bleed air to flow from the engines to a spray tube in the leading edge. Wing anti-ice is
inhibited in flight when leading edge flaps are extended and on the ground.
The wing anti-ice indication WAI is displayed beside the respective wing EICAS N1 indication when the wing
anti-ice valve is open.
Wing Anti-Ice
ON - in flight, wing anti-ice valves open to supply bleed
air to the left and right wing leading edges
- on the ground, wing anti-ice system inhibited
Off (No light) - WAI is off
VALVE Light - WAI valve position disagrees with switch position or valve in transit.
Note - WAI does not turn on continuous ignition and only heats mid-span and outboard sections of the wing
What does EICAS message ANTI-ICE NAC indicate?
TAT > 12ºC with NAI on
Which anti-ice system automatically turns on continuous ignition?
Nacille Anti-Ice
What part of the wing is anti-iced?
Mid-span
&
Outboard sections
When is WAI inhibited?
On ground
&
when leading edge flaps are extended
Quick Look - Probe Heat
Four pitot-static probes, 2-TAT probes, 2 AOA’s are heated
(4) Pitot/static probes (energized when any engine > 50% N2)
(2) TAT probes (heated in flight only with air/ground sensing)
(2) AOA (energized when any engine > 50% N2)
Note - No flight deck controls for these.
Ice Detection
Automatic Ice Detection System
- 2 ice detector probes on forward fuselage
- Provides signals to EICAS for NAI & WAI
Quick Look - Window Heat
All flight deck windows are electrically heated.
ON - Controlled heat applied to the windshield
Off (No light) - Heat off
INOP light - Windshield overheat or controller fault
- Power is removed from windshield
How do you reset a window overheat?
Switch window heat OFF for 10 seconds.
