MD Helicopters CSP-900RMM-2, Техническое обслуживание и ремонт

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CSP − 900RMM − 2 MD Helicopters, Inc.
Rotorcraft Maintenance Manual
Page 3
Revision 21
71-00-00
Metered fuel from the Fuel Metering Unit
(FMU) sprays into a reverse-flow annular
combustion chamber by a fuel manifold. Fuel
sprays into the combustion chamber from the
twelve fuel nozzles that mount on the gas
generator case. The nozzles receive fuel from
the FMU and flow divider. The fuel/air
mixture ignites and expanding gas goes to the
compressor turbine and power turbine.
The expanding gas from the combustion
chamber reverses direction and go through the
compressor turbine stator vanes to the single
stage compressor turbine. The stator vanes
make sure the expanding gas impinges upon
the compressor turbine blades at an angle that
minimizes loss of energy. The expanding gas
impinging on the turbine blades causes the
compressor turbine to rotate, this causes
rotation of the centrifugal impeller. The still
expanding gas continues an aft flow to the
power turbine stator and power turbine.
The power turbine stator makes sure the
expanding gas impinges on the power turbine
blades at an angle that minimizes loss of
energy. The expanding gases impinging on the
turbine blades causes the power turbine to
rotate, this causes rotation of the reduction
gearbox. The expanding gas then exits the
power turbine through an annular primary-
exhaust nozzle and secondary ejector and out
into the atmosphere.
B. Fireseals (Engine Firewall to Plenum
Seals)
The engine firewall to plenum seals attaches
to the forward and aft sections of the inlet
flange. Each seal attaches to the inlet flange
with fasteners that attach to the fireseal and
inlet flange.
The seals are high temperature rubber
C-shaped seals.
The seals form a fire and debris protection seal
for the inlet plenum between the compressor
case and reduction gearbox.
C. Ignition System
Each engine has an independent ignition
system that operates identically. The PW206A
ignition system supplies each engine with light
ups over a wide temperature range. The
system energizes from the battery bus through
the auto ignition relay. The system generates
from 9 to 30 Vdc.
Ignition Exciters (Ignitor Box) - There is
one engine ignitor box for each engine. The
ignitor box attaches to the airframe.
The ignition exciters supply a pulsed high
voltage output (3000 volts). When the ignitor
box energizes the exciter sends a high voltage
pulse to the ignition lead. The EEC responds
to certain parameters that indicate a potential
flameout condition. The EEC then activates
the ignition circuit for the period of time that
the condition exists.
Ignition Leads (Ignitor Cables) - Each
engine has two ignitor cables. The ignitor
cables attach to the ignitor box at one end and
the ignitor at the other end. Each ignitor cable
is a cable inside a flexible metal braiding.
Each ignitor box transmits a pulsed high
voltage output thru the engine ignitor cables
and to the ignitors.
Ignitors - There are two ignitors on each
engine at the four and five o'clock positions.
The ignitors attach to the combustor chamber
case of the engine.
Each ignitor has an electrode encased in a
semi-conducting material. The high voltage
pulse from the ignitor box crosses the gap
between the electrode and the ignitor shell.
This causes a spark to develop for light-up of
the fuel that flows into the combustor.
D. Start System
The start system for each engine supplies the
initial rotation of the PW206A engine. The
EEC controls and monitors the start system.
Starter/Generator - The starter/generator
attaches to the starter drive pad on the engine
reduction gearbox.
The generator part of the starter/generator is
a self-excited machine that uses four main
poles and four interpoles. An integral fan pulls
in air from the end of the anti-drive part of
the machine. This permits self-cooling during
rated conditions.
The starter part of the starter/generator
energizes from a 28 Vdc power source through
the essential and/or battery bus. The position
of the engine power management select switch
determines which bus supplies power.