Taxi–Out
CAUTION: Use extreme caution when taxiing on ice-covered taxiways or runways, as excessive speed or high crosswinds may start a skid. Make all turns at a reduced speed. Use smaller tiller and rudder inputs, apply minimum thrust evenly and smoothly.
Nose wheel steering .......................................................................Check Exercise nose wheel steering in both directions during taxi to circulate warm hydraulic fluid through steering cylinders and minimize steering lag caused by low temperatures.
Flaps (As required)............................................................................SET If taxi route is through slush or standing water in low temperatures or if precipitation is falling with temperatures below freezing, taxi with flaps up. Taxiing with flaps extended subjects flaps and flap drives to snow and slush accumulations from the main gear wheels. Leading edge devices are also susceptible to slush accumulations.
If exterior deicing required:
Flaps .............................................................................................. UP Prevents ice and slush from accumulating in flap cavities.
Thrust levers........................................................................... CLOSE Reduces possibility of injury to personnel at inlet or exhaust areas.
Nacelle Anti-ice switches ............................................................. ON
Pack control selectors ..................................................................OFF Reduces possibility of fumes entering the air conditioning system.
If APU operations not required:
APU selector ..........................................................................OFF APU should be shut down when deicing surfaces around the inlet to eliminate the possibility of deicing fluid entering the APU.
Copyright . The Boeing Company. See title page for details.
SP.16.4 D6-30151-425 October 1, 2000
Supplementary Procedures -Adverse Weather 747 Operations Manual
If APU operations required:
APU bleed valve switch ......................................................... OFF
CAUTION: With APU operating, ingestion of deicing fluid causes objectionable fumes and odors to enter the airplane. This may also cause erratic operation or damage to the APU.
Wait approximately one minute after completion of deicing to turn Pack selectors on to ensure all deicing fluid has been cleared from the engines:
APU bleed valve switch ................................................................ON
Pack control selectors ....................................................................ON
APU selector (As required).................... START, RELEASE TO ON
Before Takeoff
Flaps ....................................................................................................Set Extend flaps to takeoff setting at this time if they have been held due to slush, standing water, or icing conditions.
BEFORE TAKEOFF Checklist ............................................ Accomplish Accomplish the complete BEFORETAKEOFF checklist to ensure the airplane is configured for takeoff.
If airplane deicing was accomplished:
A visual inspection of the airplane wings should be made just prior to takeoff.
Engine run–up (As required) ................................................ Accomplish Takeoff in icing conditions must be preceded by a static run–up to as high a thrust setting as practical (60% N1 recommended) for approximately 30 seconds and stable engine operation checked prior to start of takeoff run.
Climb and Cruise NacelleAnti–IceOperation
Nacelle anti–ice must be used during all flight operations when icing conditions exist or are anticipated, except when the temperature is below –40°C SAT.
When operating in areas of possible icing, activate nacelle anti–ice prior to entering icing conditions. Late selection of nacelle anti–ice may allow inlet ice buildup and ice shedding into the engine.
Copyright . The Boeing Company. See title page for details.
December 01, 1999 D6-30151-425 SP.16.5
Supplementary Procedures -Adverse Weather
747 Operations Manual
In moderate to severe icing conditions for prolonged periods with N1 settings at or below 70%, or if fan icing is suspected due to high engine vibration, increase thrust on one engine at a time to a minimum of 70% N1 for 10 to 30 seconds every 10 minutes.
WARNING: Do not rely on airframe visual icing cues before activating nacelle anti–ice. Use the temperature and visible moisture criteria.
Nacelle Anti-ice switches.............................................................. AUTO
Wing Anti–Ice Operation
The wing anti–ice system may be used as a deicer or anti–icer in flight only. The primary method is to use the automatic ice detection system which acts as a deicer by allowing ice to accumulate before turning wing anti–ice on. This procedure provides the cleanest airfoil surface, the least possible runback ice formation, and the least thrust and fuel penalty.
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