Ice Detection / Protection Flashcards
What sources are used for aircraft anti-icing and de-icing?
Bleed air heat and electric heat
What uses bleed air for ice protection?
Engine lips, 3 outboard slats (2,3,4 on each wing)
What uses electric head for ice protection?
Smart probes, TAT probes, windshields, water lines, pressurization static port
If an engine fails, does the opposite wing and engine receive ice protection?
Yes. The cross bleed valve opens to provide symmetrical ice protection for both wings (the failed engine does not receive head to the engine lip)
How many ice detectors must be working to have icing detection?
One. There are 2 for redundancy
How long wil the de-icing system remain on after icing is no longer detected?
5 minutes
If ICING on the MCDU is set to OFF and takeoff roll icing conditions are encountered, will the de-icing system turn on?
Not until 1,700’ or 2 min after takeoff (whichever happens first)
Can the APU be used to provide bleed air for anti-icing?
No
What is protected from ice and rain?
Engine inlets, wing leading edge, smart probes and TAT probes, windshields, water and waste drain systems
Is the ice protection system automatic?
Yes, under normal conditions
Can a pilot override the automatic system?
Yes
How is ice detected in flight?
2 ice detectors, vibrating sensor element that changes frequency when ice builds up around it, once ice is detected, the sensor element heats, the ice melts, the normal vibrating characteristics are restored, and the heading process stops
What compressor stage is bleed air tapped for anti-icing operations?
10th High Stage Valve HSV
How is bleed air directed for pneumatic anti-ice?
Engines (independent), Wings (onside bleed)
What happens if there is a single bleed source failure?
The cross bleed automatically opens
How should the MCDU be set if there are icing conditions present on the ground?
ALL
What does selecting ALL on the MCDU provide?
Engine anti-ice ON when engines are running, Wing anti-ice ON at 40kts wheel speed
If ALL is selected on the ground, at what point will the anti-icing system become automatic? What if OFF is selected?
1,700’ AGL or 2 min after takeoff, which ever happens first, Same will occur when selected OFF
How does the failure of one of the two power sources affect the windshield heating system?
On ground inhibited, in flight left side is heated (right heats if left side has failed)
How does the failure of one of the two power sources affect the windshield heating system?
On ground inhibited, in flight left side is heated (right side heats if left side has failed)
What does TIMER selection on the windshield wiper switch do?
Activates the associated wiper in 8-second intervals
What happens if the wiper is operated on a dry windshield?
The wiper will stop, to reset the wiper move switch to OFF
When do the smart probes heat?
when an engine is running
Is there a test for the anti-ice system?
Yes, but maintenance performs this test.
How should the aircraft be configured for de-icing?
Bleeds OFF, Packs OFF, Stab trim full nose down, Flaps UP, Engines and APU ON or OFF
What does the water and waste ice protection system do?
Prevents fill drain nipples from freezing
The TRS page on the MCDU is defaulted to OFF mode, but may be selected to ALL
note
What subsystems are part of the anti-ice system?
Engine Anti-Ice System, Wing Anti-Ice System, Pitot and Static Port Heating System, Windshield Heating System, Water and Waste Ice Protection System, Ice Detection System
Once ice is detected, when will the STALL PROT ICE SPEED turn off?
After the flight has been completed, regardless of icing conditions
What stage is the engine bleed air extracted from?
Stage 10
In what position will the A/I valves from the engine to the system fail?
Open
What does the T2 sensor do?
Provides inlet temperatures to the FADEC
Why would you need to manually turn on the engine A/I?
The ice detectors won’t activate until a particular airspeed, so while on the ground, the engines may accumulate ice and turning Engine A/I ON will open the bleed valves. This can be done manually via the panel or via the MCDU TDS
Why will TDS settings be disregarded 2 min after T/O or 1,700’, whichever occurs first?
The system will revert to the default control logic so that ice accumulation can be melted whenever ice is detected.
What is the purpose of the A/I ALL setting on the MCDU TDS page?
ALL ensures A/I is used for the leading edge on the takeoff roll, not just the engines
Which slats are heated on the wing?
Slats 2, 3, and 4 (outboard of the engines)
How does the wing bleed air temperature change?
The AMS controller adjusts the signals to the bleed valves based on phase of flight. For example, in idle the 10th stage bleed valve could be fully open while in TOGA the 6th stage bleed valve could be open
Where are the wing A/I overheat detection systems located? What are they composed of?
Dual loop overheat detection systems. Installed in the left and right pylon wing areas.
What happens if a wing duct overheat is detected on the left wing?
The left and right wing A/I valves are both commanded closed. The Wing A/I system will be no-longer available.
When does the wing A/I system test itself?
In flight at 10,000’ or 10min after takeoff, whichever occurs first, the BIT is performed. The valves open. The test takes 1min or less.
What is the windshield contructed from?
Laminated glass
The outside is coated with an anti-static film
The windshield heater is a film located on the inside of the outer glass
What controls the windshield wipers?
2 independent Windshield Heater Control Units in the Fwd e-bay
Why are there 3 windshiled heating elements?
2 are connected to the windshield heater control units and 1 is a spare. One of the 2 is to conrol the heating element and the second is an overheat monitor.
When are TAT and ADSP heated?
While the engines are running
What is the purpose of the ADSP push button?
To allow ADSP heating on the ground without engines running. Only ADSP 3 will be heated by the batteries until an engine is running.
Why is there FWD and AFT drain mast heating?
To prevent ice formation during draining of water, also heating is on the waste service panel and water service panel
When should the TDS A/I be set to ENG v ALL?
The TO DATASET MENU on the MCDU must be set to ENG in the following cases when OAT is between 5°C and 10°C and:
- If there is any possibility of encountering visible moisture up to 1,700 ft AFE, 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.
The TO DATASET MENU on the MCDU must be set to ALL in the following cases when OAT is below 5°C and:
If there is any possibility of encountering visible moisture up to 1,700 ft AFE, 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.
On ground, do not rely on visual icing evidence or ice detector actuation to turn on the anti-icing system. Use the temperature and visual moisture criteria as specified above. Delaying the use of the anti-icing system until ice build-up is visible from the cockpit may result in ice ingestion and possible engine damage or flameout.
Which slats are heated?
slats 2, 3, 4 not the inbound slat 1
