The engine POWER levers actuate an engine mounted
cambox which is connected to the engine fuel control
unit (FCU) and the propeller reversing cable. The
cambox is arranged so that the reversing cable is not
affected by POWER lever movement forward of the idle
stop. When the POWER levers are lifted over the
reversing detent and moved rearward, the reversing
cable is pulled aft. This action resets the beta valve
rearward, allowing the governor to pump more oil into
the propeller, thus moving the blades through the ground
fine range toward reverse pitch. As the blades move, the
mechanical feedback collar is moved forward. This
movement is transmitted by a carbon block on the end of
the reversing lever to the beta valve, causing it to move
forward. As the POWER levers are moved further
rearward (into the striped area), the propeller blades are
moved further toward the reverse pitch stop, and the
FCU is reset to increase engine speed.
2-48. PROPELLER TACHOMETERS.
Two tachometers on the instrument panel register
propeller speed in hundreds of RPM (fig. 2-18). Each
indicator is slaved to a tachometer-generator unit
attached to the corresponding engine, installed on the
Section VII. UTILITY SYSTEMS
2-49. DEFROSTING SYSTEM.
Description. The defrosting system is an
integral part of the heating and ventilation system. The
system consists of two warm air outlets connected by
ducts to the heating system. One outlet is just below the
pilot's windshield and the other is just below the copilot's
windshield. A push-pull control placarded DEFROST
AIR, on the pilot's subpanel, manually controls airflow to
the windshield. When the control is pulled out,
defrosting air is ducted to the windshield. As the control
is pushed in, there is a corresponding decrease in
VENT BLOWER switches As required.
CABIN AIR TEMP CONTROL rheostat As
CABIN AIR, COPILOT AIR, PILOT AIR,
and DEFROST AIR controls As required.
Manual Operation. If the automatic temperature
control should fail to operate, the temperature of defrost
air and cabin air can be controlled manually by setting
the CABIN AIR MODE SELECT switch to the MAN
COOL position, then using the CABIN AIR MANUAL
TEMP switch to set the desired temperature. This
control is located on the overhead control panel
(fig. 2-15). Use the following procedure for manual
PILOT and COPILOT AIR controls In.
CABIN AIR and DEFROST AIR controls -
CABIN AIR MODE SELECT switch -
Cold air outlets As required.
CABIN AIR MANUAL TEMP switch - As
2-50. SURFACE DEICING SYSTEM.
Description. Ice accumulation is removed from
each inboard and outboard wing leading edge, both
horizontal stabilizers, stabilons, and taillets by the flexing
of deice boots which are pneumatically actuated. Bleed
air is used to supply air pressure to inflate the deice
boots, and to supply vacuum through the ejector system.
A pressure regulator protects the system from over
inflation. When the system is not in operation, a
distributor valve keeps the boots held down by vacuum
supplied through the ejector system.
below -40°C can cause permanent
damage to the deice boots.