Anti-ice Flashcards
When may the window heat power test be accomplished?
When any WINDOW HEAT Switch ON with its associated ON Light extinguished
Which windows are heated, and how are they controlled?
- L/R FWD Switch! associated No. 1 windows
* L/R SIDE Switch! associated No. 2 windows (and Nos. 4 & 5, if installed)
When is power supplied to the probe heat systems?
When the related Probe Heat Switch is ON. When the Probe Heat Switch is in the AUTO position (some aircraft), power is automatically supplied when either engine is running.
What is indicated by a COWL ANTI-ICE Light?
Overpressure in the duct downstream of the cowl anti-ice valve
How does engine or wing anti-ice affect stall warning logic?
Stall warning logic adjusts stick shaker (S/S) and min maneuver (M/M) speed bars on the airspeed indicator. FMC displayed VREF is unchanged. Stall warning logic resets when engine anti-ice turned off, unless wing anti-ice was used (resets upon landing).
What are the indications of a cowl valve which fails to go to the commanded position?
The COWL VALVE OPEN Light stays bright, and an amber TAI is illuminated above the related N1 indicator
What are the indications of a wing valve which fails to go to the commanded position?
The associated Wing Anti-Ice VALVE OPEN Light stays bright
What is the definition of icing conditions?
OAT (on ground and for takeoff), or TAT (in flight) is 10°C (50°F) or below, and visible moisture in any form is present (clouds, fog with visibility of one mile or less, rain, snow, sleet, ice crystals), or operation on ramps, taxiways, or runways where surface snow, ice, standing water, or slush may be ingested or freeze on the engines or nacelles.
When must engine anti-ice be used?
During all ground and flight operations when icing conditions exist or are anticipated, except during climb or cruise when the temperature is below -40°C SAT
When must wing anti-ice be used?
On the ground –
• Between engine start and takeoff, when icing conditions exist or are anticipated,
! unless the aircraft is, or will be protected by Type II or Type IV fluid
In flight –
• Primary method is to use as a de-icer, allowing ice to accumulate before turning wing anti-ice on
• Secondary method is to use as anti-icer only, using wing anti-ice prior to ice accumulation. This method is required during extended operations (including holding) in moderate to severe icing conditions.
If wing anti-ice required after takeoff, what is the minimum altitude for use?
1000’ AGL
What is the maximum altitude recommended for use of wing anti-ice?
FL350 – Use of wing anti-ice above this altitude may cause bleed trip off and possible loss of cabin pressure
When must the upper wing surfaces be visually inspected from the cabin prior to gate departure?
When Cold Soaked Fuel Frost (CSFF) is suspected, i.e. when
• a large amount of fuel remains in the wing tanks after landing
• frost/ice observed on lower wing surface outboard of fuel measuring stick #4
• fuel temp
During off gate deicing operations, which parts of the aircraft must be clear of frozen contamination prior to pushback?
Engine inlets
Which parts of the aircraft must be free of frozen contamination prior to engine start?
Engine inlet ducts, doors and probes, exhaust ducts, and thrust reversers. N1 fan must be free to rotate.
May hot water be used to remove frozen contamination on the engines prior to start?
No, but the contamination may be removed with limited amounts of heated deicing fluid.
When must the upper wing surfaces be visually inspected from the cabin prior to gate departure?
When Cold Soaked Fuel Frost (CSFF) is suspected, i.e. when
• a large amount of fuel remains in the wing tanks after landing
• frost/ice observed on lower wing surface outboard of fuel measuring stick #4
• fuel temp
May hot water be used to remove frozen contamination on the engines prior to start?
No, but the contamination may be removed with limited amounts of heated deicing fluid.
What amount of frozen contamination on the fuselage is acceptable?
It is acceptable to have a thin coating of hoarfrost on the fuselage, provided all vents and ports are clear and the hoarfrost does not extend down to the area of the windows. Otherwise, the fuselage must be deiced.
When may adverse weather maintenance procedures be required prior to engine start?
At ambient temperatures colder than -40°C/F (see OM1 GEN 30.3)
When must engines be idled for 2 minutes prior to changing thrust lever position?
At ambient temperatures colder than -35°C (-31°F)
What engine indications might be observed after starting in extreme cold weather?
Oil pressure may be above the normal range and the OIL FILTER BYPASS Alert may illuminate for several minutes. Operate the engine at idle until oil pressure returns to the normal range. If oil temperature stabilizes within limits and oil pressure is still above the normal range, shut down the engine.
When should ground engine run-ups be accomplished in icing conditions?
• 70% N1 (or as high as practical) for 30 seconds at 30-minute (or less) intervals when engine anti-ice is required and OAT is 3°C or below
• 70% N1 for 1 second at 10-minute (or less) intervals
when operating in freezing rain/drizzle/fog or heavy snow
• 70% N1 for 30 seconds prior to brake release at start of takeoff roll when engine anti-ice is required and OAT is 3°C or below (confirm stable engine operation)
When should ground engine run-ups be accomplished in icing conditions?
• 70% N1 (or as high as practical) for 30 seconds at 30-minute (or less) intervals when engine anti-ice is required and OAT is 3°C or below
• 70% N1 for 1 second at 10-minute (or less) intervals
when operating in freezing rain/drizzle/fog or heavy snow
• 70% N1 for 30 seconds prior to brake release at start of takeoff roll when engine anti-ice is required and OAT is 3°C or below (confirm stable engine operation)
When should in flight engine run-ups be accomplished in icing conditions?
Run up to 80% N1 (one at a time) at 15-minute intervals in moderate/severe icing conditions
After deicing/anti-icing is complete, when should flaps be extended to ensure maximum anti-icing fluid effectiveness and to avoid a significant decrease in holdover time?
Delay extension until just prior to takeoff
When must a Flight Deck Pre-Takeoff Check be accomplished?
- Several times during the holdover time period to maintain awareness of the aircraft’s condition, and
- Just prior to takeoff, when icing conditions exist and holdover time is still valid
When must a Flight Deck Pre-Takeoff Check be accomplished?
- Several times during the holdover time period to maintain awareness of the aircraft’s condition, and
- Just prior to takeoff, when icing conditions exist and holdover time is still valid
When must a Cabin Pre-Takeoff Contamination Check be accomplished?
- Required within 5 minutes of takeoff if holdover time has expired
- Required within 5 minutes of takeoff during heavy snow conditions
- Required within 5 minutes of takeoff any time a flight crew assessed change in intensity is being used
When is a Cabin Pre-Takeoff Contamination Check not authorized?
- When conditions hinder the flight crew’s ability to clearly assess aircraft condition
- When Type I fluid has been applied during freezing drizzle
- When Type II or IV fluid has been applied during conditions of freezing drizzle, light freezing rain, or rain on cold soaked wings and holdover time has expired
- When ice pellets have fallen
- When clear ice formation may be present
When is a Cabin Pre-Takeoff Contamination Check not authorized?
- When conditions hinder the flight crew’s ability to clearly assess aircraft condition
- When Type I fluid has been applied during freezing drizzle
- When Type II or IV fluid has been applied during conditions of freezing drizzle, light freezing rain, or rain on cold soaked wings and holdover time has expired
- When ice pellets have fallen
- When clear ice formation may be present
When is an External Pre-Takeoff Contamination Check not authorized?
When Type I fluid is used during freezing drizzle
What are some visual indications of fluid failure?
Any ice (other than ice pellets) or snow accumulating on top of treated surfaces is an indication that the fluid has lost its effectiveness
During cold weather operations, when are takeoffs not authorized?
Precipitation
• Moderate or heavy freezing rain
• Heavy ice pellets
Runway contamination
• Accumulations of more than 4” of dry snow
• Accumulations of more than 1⁄2” of standing water, wet snow, or slush
• Chunks of hardened snow or ice
When holding in icing conditions, may flaps be extended?
No, it is prohibited
Are takeoffs authorized in heavy snow conditions?
Yes, subject to the following restrictions:
• Aircraft must be anti-iced with undiluted Type IV fluid.
• Aircraft critical surfaces must be free of contaminants, or
aircraft must be de-iced before anti-icing fluid is applied.
• Cabin or External Pre-Takeoff Contamination Check must be performed, and takeoff must occur within 5 minutes of the most recent check
Are takeoffs authorized in heavy snow conditions?
Yes, subject to the following restrictions:
• Aircraft must be anti-iced with undiluted Type IV fluid.
• Aircraft critical surfaces must be free of contaminants, or
aircraft must be de-iced before anti-icing fluid is applied.
• Cabin or External Pre-Takeoff Contamination Check must be performed, and takeoff must occur within 5 minutes of the most recent check
Are takeoffs authorized in light or moderate ice pellets?
Yes, subject to the restrictions and allowance times outlined in OM1 GEN 30.42-30.44
After landing, when should flaps remain extended to Flaps 15 or greater until flap areas have been inspected for debris?
- After prolonged operation in icing conditions with flaps extended, or
- When an accumulation of airframe ice is observed, or
- When operating on a contaminated runway or taxiway
Which procedure should be followed to prevent deicing fluid from entering the APU during takeoff if anti-icing with Type IV fluid and TPS calls for an Engine Bleeds Off Takeoff?
Unpressurized Takeoff Procedure (OM1 GEN 30.29, SYS 20.4)
