UWAI SYSTEM CONFIGURATION
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MD-80 Sec. 4 Page 265
Flight Manual Continental Rev. 05/01/96 #24
COLD WEATHER OPERATIONS
The problems associated with cold weather operations are those concerned with low temperature and with ice and snow on the aircraft, ramps taxiways and runways. The majority of operational difficulties are encountered on the ground.
Predeparture Check
This check will determine the need for deicing. This check is usually accomplished by the flight crew during the normal walkaround inspection. Normally it will be completed at the gate, prior to departure. However qualified ground personnel may also determine the need for aircraft deicing based on their observations during company required aircraft checks, with or without the flight crew present.
The Predeparture check is a check of critical aircraft surfaces to ensure that they are free of any adhering ice, snow, slush, or frost. Critical aircraft surfaces include the following:
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Wings - Coatings of frost up to 1/8 inch in thickness on the lower wing surfaces caused by very cold fuel in the area of the wing tanks (between the front and rear spars) is permissible if, in the Captain’s opinion, it will dissipate by the time takeoff is made. All other wing surfaces must be free of ice, snow, slush or frost.
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Tail
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Control Surfaces
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Engine Inlets
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Landing Gear and Gear Doors, Wheels and Brakes
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Air Conditioning Inlets/Exits and Outflow Valves
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Airdata Sensors, Stall Vanes, Pitot Tubes and Static Ports
If these aircraft surfaces are not free of any adhering ice, snow, slush or frost, the aircraft must be deiced prior to departure.
In many cases, it may be necessary to start the engines and/or taxi to another location prior to deicing the aircraft. In situations such as this, it is permissible to start the engines and proceed to the deicing area with an accumulation of snow and/or ice on the aircraft. However, in no case will an aircraft taxi for takeoff without first ascertaining that the critical aircraft surfaces are free of any adhering ice, snow, slush, or frost.
Ice, Frost, And Snow Removal
Federal regulations prohibit takeoff when frost, snow, or ice is adhering to critical aircraft surfaces. These regulations are based on the “clean” aircraft concept which requires a pre-takeoff contamination check to ascertain that critical aircraft surfaces (wings and control surfaces) are “clean” (free of adhering ice, frost, or snow formations) and to determine that any formations not adhering to critical surfaces will blow off in the early stages of takeoff roll.
De-Icing/Anti-Icing
Aircraft de-icing/anti-icing when required, will be accomplished in accordance with the Continental GMM Section 06-14.
When freezing precipitation conditions exist, a two step deicing/anti-icing procedure will be used. The first step, deicing, is the removal of contaminates from the aircraft. This is accomplished by using diluted Types I, II or IV fluids or, at locations so equipped, by use of an Infrared (IR) de-ice system. When an Infrared system is used, aircraft will be taxi / towed to the entrance of the IR hangar where ground personnel will marshal or Ground Tower will guide the aircraft into the hangar.
Note: The IR system software limits the maximum temperature during aircraft de-icing to 120° F.
The second step, anti-icing, is a separate fluid application to protect against ice, snow, slush or frost adhering to critical aircraft surfaces. Diluted Type 1 or 100% Type II or IV fluids are used for anti-icing.
When freezing precipitation conditions do not exist and are not anticipated, a one step, deicing, procedure will be used to remove any contaminates that may have adhered to the aircraft during a previous exposure to freezing precipitation.
Aircraft may be deiced/anti-iced with the engines and/or APU shutdown or operating. In either case the air conditioning supply switches and APU air switch should be selected off to prevent fumes from entering the cabin through the air conditioning system.
After completion of deicing/anti-icing, run engines and APU for approximately one minute with the air conditioning supply switches and APU air switch selected off to ensure that all deicing/anti-icing fluid has been cleared from the engines and APU. Consider making an announcement advising passengers that a trace of odor may be sensed but it is a normal condition of deicing.
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