TM 55-1510-221-10
2-14. HAND-OPERATED FIRE EXTINGUISHER.
Repeated or prolonged exposure to high
concentrations of
monobromotrifluo-
romethane (CF3Br) or decomposition
products should be avoided. The liquid
shall not be allowed to come into contact
with the skin, as it may cause frost bite or
low temperature burns because of its very
low boiling point.
One hand-operated fire extinguisher is mounted
Tie-down provisions for a survival raft and kit
below the pilot’s seat and a second extinguisher is
are provided just forward of the toilet on the right
located on the left cabin sidewall, aft of the cabin
hand side of the cabin (fig. 2-2).
door. They are of the monobromotrifluromethane
(CF3Br) type. The extinguisher is charged to a pres-
sure 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.
NOTE
Engine tire extinguisher systems are
described in Section III.
2-15. SURVIVAL KITS.
Section III.
ENGINES AND RELATED SYSTEMS
2-16. ENGINES.
The aircraft is powered by two PT6A-41 turbo-
prop engines (fig. 2-11). The engine has a three stage
axial, single stage centrifugal compressor, driven by
a single stage reaction turbine. The power turbine, a
two stage reaction turbine, counter-rotating with the
compressor turbine, drives the output shaft. Both
the compressor turbine and the power turbine are
located in the approximate center of the engine with
their shafts extending in opposite directions. 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 capaci-
tance discharge ignition unit and two spark igniter
plugs are used to start combustion. After combus-
tion, the exhaust passes through the compressor tur-
bine and two stages of power turbine then is routed
through two exhaust ports near the front of the
engine. A pneumatic fuel control system schedules
fuel flow to maintain the power set by the gas gener-
ator power lever. The accessory drive at the aft end
of the engine provides power to drive the fuel
pumps, fuel control, the oil pumps, the refrigerant
compressor (right engine), the starter-generator, and
the turbine tachometer transmitter. The reduction
gearbox forward of the power turbine provides gear-
ing for the propeller and drives the propeller
tachometer transmitter, the propeller overspeed gov-
ernor, and the propeller governor.
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 pro-
peller spinner and forward cowling, and exhausting
through ducts in the upper and lower aft cowling.
2-18. AIR INDUCTION SYSTEMS - GENERAL.
Each engine and oil cooler receives ram air duc-
ted from an air scoop located within the lower sec-
tion of the forward nacelle. Special components of
the engine induction system protect the power plant
from icing and 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
the compressor.
2-20
