ICE AND RAIN PROTECTION
- The ice and rain protection system allows unrestricted operation of the aircraft in icing
conditions and heavy rain.
1. ANTI-ICE
Either hot air or electrical heating protects critical areas of the aircraft as follows:
HOT AIR
‐ Three outboard leading-edge slats of each wing
‐ Engine air intakes.
ELECTRICAL HEATING
‐ Flight compartment windows
‐ Sensors, pitot probes and static ports
‐ Waste-water drain mast.
1.1 WING ANTI-ICE
- In flight, hot air from the pneumatic system heats the three outboard slats (3-4-5) of
each wing.
- Air is supplied through one valve in each wing (2 valves 2 wings)
- When the aircraft is on ground, the flight crew can initiate a 30 s test sequence by
turning the system ON.
- If the system detects a leak during normal operation, the affected side’s wing anti-ice
valve automatically closes
- When wing anti-ice is selected, the N1 or EPR limit is automatically reduced, and the
idle N1 or EPR is automatically increased.
- If the electrical power supply fails, the valves close.
- Air reaches slat 3 through a telescopic duct. It is distributed to the outboard slats by
piccolo ducts, interconnected by flexible connections.
- Only the three outboard slats are protected by the hot anti-icing air. Due to the
aerodynamic characteristics of the wing, slats 1 and 2 do not need to be protected.
Notes:
1. In case of failure, the aircraft may be dispatched per Minimum Equipment List with
the RH WING anti-ice valve deactivated in the OPEN position or either valve (2 valves)
in the CLOSED position.
- If the valve is deactivated OPEN, the associated engine bleed switch must be selected
OFF until after takeoff (until 1,500ft AGL). A flight manual performance penalty is
applied (fuel consumption is increased by 1%) we need to check MEL operation
depending on altitude. Affected ENG BLEED is OFF to prevent SLAT is damage by heat
- If the valve is deactivated CLOSED, the aircraft may not be flown into icing
conditions, flight time < 1.5h, 1 flight to main base only
2. The amber FAULT light comes on briefly as the valves transit.
3. ICE NOT DET: This memo appears in green, if ice is no longer detected after 190 s.
4. For NEO, WAI will be appeared on EWD
5. Wings that are thin or have sharp leading edges are more efficient ice collectors. For
this reason, smaller, thin airfoils may accrete more ice faster than larger, thick airfoils.
A large transport aircraft will accrete proportionally less ice than a smaller aircraft
traversing the same icing environment. Also, if the leading edge radius of the wing
decreases from root to tip (as it frequently does in swept or tapered wings), the ice
accretion will be proportionately greater near the tip. Therefore, only slat 3,4,5 are anti
ice. Vertical and horizontal stabilizers are not requiring for this. Manufacturer just make
bigger stabilizers, put weight penalty in increasing Vapp rather than established
complicated anti ice system for stabilizers
1.2 ENGINE ANTI-ICE
- An independent air bleed from the high pressure compressor protects each engine
nacelle from ice (from the 7th stage of high pressure compressor)
- The valve automatically closes, if air is unavailable (engine not running).
- When an engine anti-ice valve is open, the N1 or EPR limit is automatically reduced
and, if necessary, the idle N1 or EPR is automatically increased for both engines in order
to provide the required pressure.
- If electrical power fails, the valves open.
Notes:
For NEO:
- Two Pressure Regulated & Shut off Valves (PRSOV) enable the flow of bleed air to the
engines air intake inlet. Only one PRSOV is performing the shut off function when the
engine anti-ice is off.
- The NAI will be displaced on EWD
1.3 WINDOW HEAT
- The aircraft uses electrical heating for anti-icing each windshield and defogging the
cockpit side windows.
- 2 Independent Window Heat Computers (WHCs), one on each side, automatically
regulate the system, protect it against overheating, and indicate faults. Window heating
comes on:
Automatically when at least one engine is running, or when the aircraft is in
flight.
Manually, before engine start, when the flight crew switches ON the
PROBE/WINDOW HEAT pushbutton switch.
- Windshield heating operates at low power on the ground and at normal power in
flight…
- Only one heating level exists for the windows.
1.4 PROBES HEAT
Electrical heating protects:
‐ Pitot probes
‐ Static ports
‐ Angle-Of-Attack (AOAs) probes
‐ Total Air Temperature (TAT) probes.
3 independent Probe Heat Computers (PHCs) automatically control and monitor:
‐ Captain probes
‐ F/O probes
‐ STBY probes.
They protect against overheating and indicate faults.
The probes are heated:
‐ Automatically when at least one engine is running, or when the aircraft is in flight.
‐ Manually, when the flight crew switches ON the PROBE/WINDOW HEAT pb. Only at
least one engine is running, this function is active
- On the ground, the TAT probes are not heated and pitot heating operates at a low level
(the changeover to normal power in flight is automatic).
2. ICE DETECTION SYSTEM
