They are of the monobromotrifluoromethane (CF3Br)
type. The extinguisher is charged to a pressure of 150
to 170 PSI and emits a forceful stream. Use an
extinguisher with care within the limited area of the
cabin to avoid severe splashing.
described in Section III.
2-15. SURVIVAL KITS.
Tie-down provisions for three survival rafts and
kits are provided just aft of the toilet on the right side of
the aft cabin area.
ENGINES AND RELATED SYSTEMS
The aircraft is powered by two PT6A-67 turboprop
engines, rated at 1200 SHP (fig. 2-11). Each engine is
equipped with a hydraulically controlled, reversible,
constant-speed, four-bladed full-feathering propeller.
The engines are reverse-flow free turbines, employing
centrifugal compressors in combination, driven by the
gas generator turbine. The gas generator turbine and
the two power turbines are in line with each other and
have opposite rotations. The power turbines are
connected through planetary reduction gearing to a
flanged propeller shaft. The oil tank, filler cap and
dipstick are an integral part of the engine.
Being a reverse flow engine, the ram air supply
enters the lower portion of the nacelle and is drawn in
through the aft protective screens. The air is then
routed into the compressor. After it is compressed, it is
forced into the annular combustion chamber, and mixed
with fuel that is sprayed in through 14 nozzles mounted
around the gas generator case. A capacitance
discharge ignition unit and two spark igniter plugs are
used to start combustion. After combustion, the exhaust
passes through the compressor turbine and two stages
of power turbines, then is routed through two exhaust
ports near the front of the engine. A pneumatic fuel
control system schedules fuel flow to maintain power set
by the gas generator POWER lever. The accessory
drive at the aft end of the engine provides power to
drive the fuel pumps, fuel control, oil pumps, refrigerant
compressor (right engine), starter/generator, and the
tachometer generator. The reduction gearbox forward
of the power turbine provides gearing for the propeller
and drives the propeller tachometer generator, the
propeller overspeed governor, and the propeller primary
2-17. ENGINE COMPARTMENT COOLING.
The forward engine compartment including the
accessory section is cooled by air entering around the
exhaust stack cutouts, the gap between the propeller
spinner and forward cowling, and exhausting through
louvers in the upper forward aid aft cowling.
2-18. AIR INDUCTION SYSTEMS - GENERAL.
Each engine and oil cooler receives ram air,
ducted from separate air inlets located within the lower
section of the forward nacelle. Induction system
components protect the power plant from icing and
reduce the possibility of foreign object damage.
2-19. FOREIGN OBJECT DAMAGE CONTROL.
The engine has an integral air inlet screen
designed to obstruct objects large enough to damage
2-20. ENGINE ICE PROTECTION SYSTEMS.
Inertial Separator. An inertial separation
system is built into each engine air inlet to prevent
moisture particles from entering the engine inlet plenum
under icing conditions. A movable vane and a bypass
door are lowered into the airstream when operating in
visible moisture at 5 °C or colder, by energizing
electrical actuators with the switches, placarded # 1 and
# 2 ICE VANE CONTROL - ON, located on the
overhead control panel (fig. 2-13). The system
operates identically to the main system. The back-up
ice vane system is controlled by two switches placarded
#1 and #2 ICE VANE POWER SELECT - MAIN -
STANDBY, located on the overhead control panel (fig.
2-13). If the main system fails, placing the switch in the
STBY position will allow use of the back-up system.
Electrical protection is provided through two 5-ampere
circuit breakers placarded ICE VANE CONTR MAIN and
ICE VANE CONTR AUXILIARY, located on the
overhead circuit breaker panel.
Engine Ice Protection Systems Operation.
The vane deflects the ram airflow slightly downward to
introduce a sudden turn in the airflow to the engine,
undeflected, because of their greater momentum, and
be discharged overboard.
Once the ice vane system is actuated, the
extended position of the vane and bypass door is
indicated by green annunciators, placarded # 1 VANE
EXT and #2 VANE EXT located on the caution/advisory
panel. If for any reason the vane(s) do not attain the
selected position within 33 seconds, an amber #1 VANE
FAIL or # 2 VANE FAIL annunciator(s) illuminates on
the caution/ advisory panel.