曝光台 注意防骗
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several degrees above freezing. A 15°F temperature rise may be affected by a 100 KCAS
increase coincident with the corresponding rise in Total Air Temperature. The ability to affect
this temperature rise below 10,000 ft MSL is limited by the 250 kt speed limit. Also, if the OAT
is extremely cold, this procedure will not work.
Trace, light, moderate, and severe describe the intensity of icing that will vary among airplanes
for the same cloud depending on airplane size, speed, and altitude.
Extent of ice accretion, shape, roughness, and height are the most important factors in the effect
on an airfoil. Unfortunately, operational descriptors of rime, clear, or mixed ice are not adequate
to accurately convey shades of color of the icing environment and the hazards of Supercooled
Large Droplets (SLD). Ice forming aft of the anti-ice devices may be white, milky, or clear.
Non-hazardous ice may also be described using the same terms. In the same cloud, one airplane
may accrete rime while another—at a higher speed—accretes mixed ice.
GULFSTREAM AEROSPACE
GIV AIRPLANE FLIGHT MANUAL
ADVERSE WEATHER/ABNORMAL
ATMOSPHERIC CONDITIONS
APPENDIX E
E-14 FAA APPROVED
31 May 2001
Where Does Ice Accrete?
Where ice builds up on a given airfoil depends on the AOA, airspeed, and icing variables. Ice
tends to accrete more on the upper surface at low angle-of-attack associated with higher speeds
or flap extension or during descent. Ice tends to accrete more on the lower surface at higher
angle-of-attack (slower airspeed or heavier weight).
Normal Icing Cues
Visual or tactile icing cues signal the potential for ice to form, the presence of ice accretion, or
icing severity. Cues may vary somewhat among airplane types, but typically include:
• temperature below freezing combined with visible moisture,
• ice on the windshield wiper arm, winglets, wing leading edges
or
• ice detector (if installed) annunciation.
Tactile cues such as vibration, buffet, or changes in handling characteristics normally trigger a
mental warning that ice has already accreted to a perceptible, and perhaps, detrimental level.
Typically, as ice increases in thickness, cues become more prominent.
Ice can contribute to partial or total wing stall followed by roll, aileron, snatch, or reduced aileron
effectiveness.
Wing stall is not an uncommon consequence of ice accretion. Ice from freezing drizzle can form
sharp edged roughness elements approximately 5 to 10 mm high over a large chordwise expanse
of the wings lower surface (perhaps covering 30 to 50%) and fuselage, increasing drag
dramatically and thereby reducing speed. Proper airspeed control will minimize the potential for
wing stall. Correcting for ice accumulation demands increased power, increased AOA, or both to
maintain altitude. If actual stall is encountered (identified by wing roll-off), lower the nose
(decrease AOA), accept any altitude loss required to recover from the stall, then increase power
after recovery and return to previously assigned altitude.
GULFSTREAM AEROSPACE
GIV AIRPLANE FLIGHT MANUAL
ADVERSE WEATHER/ABNORMAL
ATMOSPHERIC CONDITIONS
APPENDIX E
FAA APPROVED E-15
31 May 2001
Tailplane stall in a Gulfstream airplane has not been experienced but can occur in icing
conditions as the airplane is configured for landing. If tailplane stall does occur (identified by
pitch down), retract flaps to the previous position and raise nose to increase AOA while slowing
airspeed to minimum maneuvering speed for the current flap setting. After recovery, increase
power and return to previously assigned altitude.
Loss of roll control effectiveness is a different situation, and perhaps the more dangerous.
Because of flow disruption over the wing ahead of the ailerons, the controls do not produce the
rolling moments associated with a given deflection and airspeed. This can affect airplanes of any
size.
When reduction or loss of aileron control due to ice is experienced, it may or may not be
accompanied by abnormally light control forces. If the airplane is displaced in roll attitude, for
instance, caused by partial stall due to ice, the pilot’s efforts to correct the attitude by aileron
deflection are defeated by the lack of their effectiveness. To recover, lower pitch (decrease
AOA), increase airspeed, and roll wings level. After recovery, increase power and return to
previously assigned altitude.
INFLIGHT PROCEDURES
Engine Icing
Engine icing can occur without wing icing. A jet engine operating in an air mass with an
ambient temperature below 8°C may experience engine icing; this is caused by the temperature
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湾4飞机飞行手册AFM Gulfstream IV AIRPLANE FLIGHT MANUAL 2(146)
