7-13 CONTROL LOCK
To prevent damage to the ailerons, elevator, and rudder systems, caused by
wind buffeting while the airplane is parked, a control lock is provided to lock
the ailerons, elevator, and rudder in place. The lock consists of a steel pin
which is inserted through holes in the control tube and a locking mechanism
for the rudder pedals. The steel pin has a ag that identies it as a control
lock and provides a warning statement for removal prior to starting the engine.
To install the control lock, align the hole in the upper portion of the pilot’s
control wheel shaft with the hole in the shaft collar on the instrument panel
and insert the rod into the aligned holes. Installation of the lock will secure
the ailerons in their neutral position and the elevators in the full trailing edge
down position. Proper installation of the lock will place the ag directly in front
of the pilot’s view of the instrument panel.
To install the rudder gust lock, position the pedal sleeves over the top of the
rudder pedals and then lock the seat track anchor into the anchor point.
7-14 ENGINE
The Pratt & Whitney Canada PT6A-34 powerplant is a lightweight, reverse
ow, free power turbine engine. It utilizes two independent turbines; one
turbine drives the compressor in the gas generator section and the second
drives the propeller through a reduction gearbox.
Inlet air enters near the rear of the engine through an annular plenum
chamber formed by the compressor inlet case where it is directed to the
compressor section. The compressor consists of three axial stages and a
single centrifugal stage, all assembled as an integral unit. A row of stator
vanes, located between each stage of compression, diffuses the air, raises
its static pressure and directs it to the next stage of compression. The
compressed air passes through diffuser tubes which turn the air through
ninety degrees in direction and converts velocity to static pressure. The
resultant compression ratio of the engine is 7.0:1.
The diffused air then passes through straightening vanes to the annulus
surrounding the combustion chamber liner. The combustion chamber liner
consists of an annular weldment that has perforations of various sizes,
allowing entry of compressor delivery air. The ow of air changes direction
180 degrees as it enters and mixes with fuel. The fuel/air mixture is ignited
and the resultant expanding gases are directed to the turbines. The location of
the liner eliminates the need for a long shaft between the compressor and the
compressor turbine, thus reducing the overall length and weight of the engine.
Fuel is injected into the combustion chamber liner through 14 simplex
nozzles, 10 primary and 4 secondary, for ease of starting. Fuel is supplied
by a dual manifold consisting of primary and secondary transfer tubes and
adapters. The fuel/air mixture is initially ignited during starting by two spark
igniters which protrude into the liner. The resultant gases expand from the
liner, reverse direction in the exit duct zone and pass through the compressor
turbine inlet guide vanes to the compressor turbine. The guide vanes ensure
that the expanding gases impinge on the turbine blades at the correct angle,
with minimum loss of energy. The still-expanding gases are then directed
forward to drive the power turbine.
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