accumulated from the spray of slush or water. Monitor
BRAKE DE-ICE annunciator for automatic termination of
system operation and then turn the switch OFF.
Flight controls. During flight, trim tabs and
controls should also be exercised periodically to prevent
(3) Anti-icing equipment. Insure that anti-icing
systems are activated-before entering icing conditions.
Do not activate the surface de-ice system until ice has
accumulated one-half to one inch. The propeller de-ice
system operates effectively as an anti-ice system and it
may be operated continuously in flight. If propeller
imbalance due to ice does occur, it may be relieved by
increasing RPM briefly, then returning to desired setting.
Do not operate deicer boots continuously.
Continuous operation tends to balloon the
ice over the boots. Allow at least 1/ 2 inch
of ice to accumulate on the surface boots
and 1/8 to 1/4 inch of ice to accumulate on
the antenna boots, then activate the deicer
boots to remove the ice. Repeat this
procedure as required.
(4) Ice vanes. Ice vanes must be extended
when operating in visible moisture or when freedom from
visible moisture cannot be assured, at 5°C FAT or less.
Ice vanes are designed as an anti-ice system, not a de-ice
system. After the engine air inlet screens are blocked,
lowering the ice vanes will not rectify the condition. Ice
vanes should be retracted at 15°C FAT and above to
assure adequate engine oil cooling.
(5) Stall speeds. Stalling airspeeds should be
expected to increase when ice has accumulated on the
aircraft causing distortion of the wing airfoil. For the same
reason, stall warning devices are not accurate and should
not be relied upon. Keep a comfortable margin of
airspeed above the normal stall airspeed. Maintain a
minimum of 140 knots during sustained icing conditions to
prevent ice accumulation on unprotected surfaces of the
wing. In the event of windshield icing, reduce airspeed to
226 knots or below.
Descent. Use normal procedures in Section II.
Brake icing should be considered if moisture was
encountered during previous ground operations or inflight
in icing conditions with gear extended.
Landing. Landing on an icy runway should be
attempted only when absolutely necessary and should not
be attempted unless the wind is within 10 degrees of
runway heading. Application of brakes without skidding
the tires on ice is very difficult, due to the sensitive
brakes. In order not to impair pilot visibility, reverse thrust
should be used with caution when landing on a runway
covered with snow or standing water. Use the procedures
in Section II for normal landing.
Engine Shutdown. Use normal procedures in
Before Leaving the Aircraft. When the aircraft is
parked outside on ice or in a fluctuating freeze-thaw
temperature condition the following procedures should be
followed in addition to the normal procedures in Section II.
After wheel chocks are in place, release the brakes to
condensation, remove any accumulation of dirt and ice
from the landing gear shock struts, and install protective
covers to guard against possible collection of snow and
8-69. DESERT OPERATION AND HOT WEATHER
Dust, sand, and high temperatures encountered
operational life of the aircraft and its equipment. The
abrasive qualities of dust and sand upon turbine blades
and moving parts of the aircraft and the destructive effect
of heat upon the aircraft instruments will necessitate
hours of maintenance if basic preventive measures are
not followed. In flight, the hazards of dust and sand will
be difficult to escape, since dust clouds over a desert may
be found at altitudes up to 10,000 feet. During hot
weather operations, the principle difficulties encountered
are high turbine gas temperatures (TGT) during engine
starting, overheating of brakes, and longer takeoff and
landing rolls due to the higher density altitudes. In areas
where high humidity is encountered, electrical equipment
(such as communication equipment and instruments) will
be subject to malfunction by corrosion, fungi and moisture
absorption by nonmetallic materials.
Preparation For Flight. Check the position of the
aircraft in relation to other aircraft. Propeller sand blast
can damage closely parked aircraft. Check that the
landing gear shock struts are free of dust and sand.
Check instrument panel and general interior for dust and
sand accumulation. Open main entrance door and
cockpit vent storm windows to ventilate the aircraft.