TM 55-1510-215-10
reverse the propellers (fig. 2-21). This light illuminates
only when the landing gear handle is down, and if
CAUTION
circuit is protected by a 5-ampere circuit breaker,
placarded LDG GR CONTROL, located on the fight
To prevent damage to reversing
subpanel (fig. 2-7).
linkage and an asymmetric thrust
condition, propeller levers must be in
b. Propeller Primary Pitch Annunciator Lights. Two
HIGH RPM position prior to propeller
yellow lights placarded L PRI PITCH and R PRI PITCH
reversing.
are located on the caution annunciator panel (fig. 2-22).
Illumination of a light indicates malfunction of the normal
The propeller blade angle may be reversed to
propeller low-pitch stop, and that the secondary low pitch
shorten landing roll. To reverse, propeller levers are
functions for the affected propeller. Propeller reverse
positioned at HIGH RPM (full forward), and the power
pitch operation must not be attempted while either of
levers are lifted up to pass over an IDLE detent, then
these lights are illuminated. Refer to chapter 9.
pulled aft into REVERSE setting. In REVERSE position,
each power lever overrides the corresponding secondary
2-51. Propeller Tachometer.
idle stop, allowing engine power for the beta and reverse
ranges. Power levers must be pulled back through
Two tachometers on the instrument panel register
normal idle speed range before being positioned in
propeller speed in hundreds of RPM (fig. 2-22). Each
REVERSE.
indicator is slaved to a tachometer generator unit
attached to the corresponding engine.
a. Propeller Reverse Not-Ready Annunciator Light.
One yellow caution light, placarded REVS NOT READY,
on the caution annunciator panel alerts the pilot not to
Section VII. UTILITY SYSTEMS
2-52. Defrosting System.
NOTE
a. Description.
The defrosting system is an
For maximum windshield defrosting,
integral part of the heating and ventilation system. The
pull out the CABIN AIR, VENT AIR,
system consists of two warm air outlets connected by
and DEFROST AIR controls and
ducts to the heating system. One outlet is just below the
position the HTR switch to MAN.
pilot's windshield and the other is below the copilot's
Regulate the temperature by opening
windshield. A push-pull control, placarded DEFROST
one or more of the cold air outlets.
AIR, on the right subpanel (fig. 2-7), manually controls
airflow to the windshield. When pulled out, defrosting air
c. Emergency Operation.
If the automatic
is ducted to the windshield. As the control is pushed in,
temperature control should fail to operate, the
there is a corresponding decrease in airflow.
temperature (of defrost air and cabin air) may be
controlled manual by manipulating the HTR control
b. Normal Operation
switch between the OFF and MAN positions.
1. Vent blower operation - Check.
2-53. Surface Deicer System.
2. HTR switch - AUTO.
a. Description. Ice accumulation is removed from
each outboard wing leading edge, both horizontal
3. CABIN TEMP control - As required.
stabilizers, and the vertical stabilizer by the flexing of
deicer boots which are pneumatically actuated. Engine
4. CABIN AIR, VENT AIR, and DEFROST
bleed air, from the engine compressor, is used to supply
AIR controls - As required.
air pressure to inflate the deicer boots, and to supply
vacuum, through the ejector system, for boot hold down
during flight.
2-37
