water. Monitor BRAKE DEICE ON ammunciator for auto-
matic termination of system operation and then turn the
switch OFF. During flight, trim tabs and controls should
also be exercised periodically to prevent freeing. Ensure
that anti-icing systems are activated before entering icing
conditions. Do not activate the surface deice system until
ice has accumulated at least 0.5 INCH The propeller deice
system operates effectively as an anti-ice system and it
may be operated continuously in flight If propeller imbal-
ance due to ice does occur, it may be relieved by increas-
ing RPM briefly, then returning to desired setting.
Ice vanes must be extended when opening 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 deice system. After the engine air
inlet screens are blocked, lowering the ice vanes will not
rectify the condition
(2) 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 accumula-
tion on unprotected surfaces of the wing. In the event of
windshield icing, reduce airspeed to 226 KNOTS or below.
h. Descent. Use normal procedures in Section II.
Brake deicing should be considered if moisture was
encountered during previous ground operations or in flight,
in icing conditions with gear extended.
i. Landing. Landing on an icy runway should be
attempted only when absolutely necessary and should not
be attempted unless the wind is within 10° of runway head-
ing. 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 procedures in Section II for normal
j. Engine Shutdown. Use normal procedures in Sec-
k. Before Leaving Aircraft. When the aircraft is
parked outside on ice or in a fluctuating freeze-thaw tem-
perature condition the following procedures should be fol-
lowed in addition to the normal procedures in Section II.
After wheel chocks are in place, release the brakes to pre-
vent freezing. Fill fuel tanks to minimize 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 ice.
8-49. DESERT OPERATION AND HOT WEATHER
Dust, sand, and high temperatures encountered during
desert operation can sharply reduce the operational life of
the aircraft and its equipment The abrasive characteristics
of dust and sand upon turbine blades and moving parts of
the aircraft and the destructive effect of heat upon the air-
craft instruments will necessitate many hours of mainte-
nance 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 principal difficulties encountered are high turbine gas
temperatures (TGT) during engine starting, over-heating of
brakes, and longer takeoff and landing distances due to the
higher density altitudes encountered 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 absorp-
tion by nonmetallic materials.
a. Preparation For Flight. Check the position of the
aircraft in relation to other aircraft Propeller blown sand
can damage nearby 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
b. Engine Starting. Use normal procedures in Section
IL Engine starting under conditions of high ambient tem-
peratures may produce a higher than normal TGT during
the start. The TGT should be closely monitored when the
CONDITION lever is moved to the LOW IDLE position
If overtemperature tendencies are encountered, the CON-
DITION lever should be moved to IDLE CUTOFF position
periodically during acceleration of gas generator RPM
(N 1 ). Be prepared to abort the start before temperature lim-
itations are exceeded.
c. Warm-Up Ground Tests. Use normal procedures
in Section II.
d. Taxing. Use normal procedures in Section II.
When practical, avoid taxiing over sandy terrain to mini-
mize propeller damage and engine deterioration that results
from impingement of sand and gravel. During hot weather
operation, use minimum braking action to prevent brake
e. Takeoff. Use normal procedures in Section II.
Avoid taking off in the wake of another aircraft if the nut-
way surface is sandy or dusty.