Cold Weather Ops Flashcards
When can icing conditions exist?
Icing conditions may exist when the total air temperature is 10 °C or less and visible moisture is present in any form
(clouds, fog with visibility of 1 mile or less, rain, snow, sleet, or ice crystals).
What effects can icing have on an aircraft?
-Increased takeoff speeds, takeoff distances, stall speeds, and landing distances.
-Reduced rate of climb and lower service ceilings.
Increased power requirements, causing increased fuel consumption and decreasing range and endurance.
-Noticeable decrease in airplane maneuverability, including reduced directional stability and control at high sideslip angles, and heavier than normal stall buffet when approaching stall airspeeds (more prominent as flaps settings approach zero).
-Reduced engine power due to obstruction of the engine inlet air duct.
-When using anti-icing/deicing systems, fuel consumption increases and engine power is reduced.
When should you turn on the engine anti ice system?
The engine ice protection system must be on for taxi and takeoff when operating in visible moisture with an ambient temperature of 10 °C or less. If engine ice protection is not switched on, ice may enter the engine air inlet and cause engine power fluctuations. This can cause the propeller to autofeather or damage the engine.
When does the ice protection system become operative in Auto mode?
60 KIAS
What TOLD numbers should you use during computation during icing conditions?
When operating in icing conditions, performance data should be calculated based on the charts for the all bleed condition.
When can you use the wing/empennage protection system in anti ice mode?
The wing/empennage ice protection system should not be operated in the anti-icing mode except during approach and landing. Operation at power settings above 2500 HP at temperatures below −30 °C or at pressure altitudes above 20,000 feet at any HP may degrade engine life.
What are some the approach consideration when icing has been encountered within 6 minutes of landing?
For approaches when icing conditions have been encountered within approximately 6 minutes of landing, do not fly slower than 100% flaps approach and threshold speeds plus 6 knots and add any gust factor up to a cumulative total of 10 knots. For 50% flaps
landings increase approach and threshold speeds by 10 knots and do not add a gust factor.
How is clean air icing identified and what must be done about it?
This icing is caused by the sudden drop in temperature resulting from pressure loss in the engine inlet air
duct. Such icing is indicated by a falling HP indication. If HP indication falls for no apparent reason, assume that engine inlet air duct icing is occurring, and take the following action immediately.
1. ENG switch on ICE PROTECTION panel - ON
2. Increase airspeed to the maximum consistent with a continuous operation, to increase ram pressure in the air duct.
3. Seek an altitude that is less likely to produce air duct icing
What is cold weather defined as?
Cold weather is generally considered to be 0 °C (32 °F) and below.
How much frost is permitted on the underwing?
Light frost up to 1/8 inch thick caused by cold soaked fuel is permitted on the lower wing surface, immediately below the fuel tank area, if the fuselage and all other control surfaces are free of all icing. If deicing is required on any other airplane surface, the underwing frost shall also be removed.
What are is the engine start procedure for moderately cold tempertures?
- Switch underfloor heat off before engine start.
NOTE
The PROPELLER CONTROL switch, for the engine being started, should not be switched to FEATHER until just
prior to start.
- Start the engines with the propeller control switches in FEATHER and Low Speed Ground Idle (LSGI) selected (Hotel mode).
- Observe normal engine starting limits except NG must be 60 percent or higher and NP should be between 15 percent and 30 percent.
- Switch underfloor heat to HEAT/FAN once the engines have stabilized.
- Operate the engine in Hotel mode until oil temperature is above 15 °C and rising.
- Unfeather the propeller and operate the engine in LSGI until oil temperature is above 45 °C and rising.
What are the shutdown procedures in cold weather?
- Switch the cross flow valve to full OPEN. This ensures that the air conditioning system is set for subsequent cold weather starting.
- After shut down in LSGI and NP has decreased to zero, feather the propeller and return the propeller control switch to NORM.
- Switch the oil cooler flaps to CLOSE/fixed.
- Flaps should be up to prevent ice or snow collecting in the flaps well.
- If the airplane is to remain outside for more than 4 hours at temperatures below −18 °C (0 °F) or for more than 1 hour at temperatures below −26 °C (−15 °F), remove the batteries and store them in a heated
area.
