曝光台 注意防骗
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entering icing conditions. Late selection of nacelle anti–ice may allow inlet ice
buildup and ice shedding into the engine.
December 01, 1999
747 Operations Manual
Copyright © The Boeing Company. See title page for details.
SP.16.6 D6-30151-425
Supplementary Procedures -
Adverse Weather
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.
Note: After the flaps are up, wing anti–ice should be used to melt any
accumulation of slush.
The secondary method is to use wing anti-ice prior to ice accumulation. Operate
the wing anti–ice system as an anti–icer only during extended operations in
moderate or severe icing conditions, such as holding.
Ice accumulation on the flight deck window frames, windshield center post, or
windshield wiper arm, or side windows may be used as an indication of structural
icing conditions and the need to turn on wing anti–ice.
Normally, it is not necessary to shed ice periodically unless extended flight
through icing conditions is necessary (holding).
CAUTION: Do not operate wing anti-ice when total air
temperature (TAT) is above 10°C (50°F).
Note: Wing anti-icing is not effective with leading edge flaps
extended. If icing conditions exist, turn wing anti-icing on after
retraction of leading edge flaps; or complete wing anti-icing
prior to extension of leading edge flaps.
Note: Prolonged operation in icing conditions with the leading edge
and trailing edge flaps extended is not recommended.
Secure
The flight crew should ensure the following actions are accomplished as required:
April 01, 2001
747 Operations Manual
Supplementary Procedures -
Adverse Weather
Copyright © The Boeing Company. See title page for details.
D6-30151-425 SP.16.7
Outflow Valve Manual switches .........................................................ON
Outflow Valve Manual control ....................................................CLOSE
Inhibits intake of snow and ice.
Wheel chocks ....................................................................Check in place
Parking brakes .................................................................................. OFF
Eliminates the possibility of brakes freezing.
Protective covers and plugs ........................................................ Installed
Water storage containers..............................................................Drained
Toilets ..........................................................................................Drained
Doors ............................................................................................Closed
Hot Weather Operation
During flight planning, consider the following:
• high temperatures inflict performance penalties which must be
taken into account on the ground before takeoff
• alternate takeoff procedures (Packs Off Takeoff, APU-to-Pack
Takeoff, etc.)
During ground operation, consider the following to help keep the airplane as cool
as possible:
• all packs should be used (when possible) for maximum cooling
• recirculation fans should be off because the fans add warm air to
the conditioned air
• if cooling air is available from an outside source, the supply should
be plugged in immediately after engine shutdown and should not
be removed until just prior to engine start
• keep all doors and windows, including cargo doors, closed as much
as possible
• electronic components which contribute to a high temperature level
in the flight deck should be turned off while not needed
• all air outlets on flight deck should be open
April 01, 2001
747 Operations Manual
Copyright © The Boeing Company. See title page for details.
SP.16.8 D6-30151-425
Supplementary Procedures -
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