asgmnt pneu eng starting.ppt
TRANSCRIPT
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4 Aeroplane 3
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PNEUMATIC STARTING SYSTEM
To rotate engine to the rpm range where starting can be
accomplished.
Controlled by two start switches (located on the
forward overhead panel)
two pneumatic starters two starter valves
associated pneumatic plumbing
Consists
of
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CENTER INSTRUMENT
PANEL
FORWARD OVERHEAD
PANEL
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COMPONENT LOCATION
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GENERAL
Air pressure in the pneumatic manifold
Engine accelerate to starting speed & engine start
Starter rotate & transmitted to the N2 compressor
through the accessory drive gear system
Low pressure heat the pneumatic starterturbine blades
Start switch supply electrical power to open the
starter valve
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Start switch Control the system
4-position rotary switches
Other than ground start position
switch remain in its original
position until another selection is
made.
Electrical power source 28 -volt dc battery bus
115-volt ac transfer bus
115-volt ac standby bus
GRD, OFF, CONT and FLT
3 separatecompressed
air sources:
-APU-Ground carts
-Cross-bleed air
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Lightweight turbine-type air motor
Converts kinetic energy starting torque
Use low pressure air and electrical power for starter operation.
5 basic parts:
PNEUMATIC STARTER
Scroll assembly
Turbine wheel
Reduction gear assembly Engaging mechanism
Output shaft
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Starter valve
open admit air to
the inlet
connection passes through the
starter vanes (starter
scroll ass.) air directed radially
inward ( throughturbine wheel )
give high
speedrotation
Exhaust air passes
air outlet screen or
turbine wheel
containment ass.
(reduction gear)transmit high
speed, low torque
low speed,
high torque
Transmitted
to output
shaft
Transmitted
to the N2
compressor
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.
speed of output shaft >
speed of internal gear hub clutch mechanism
provide automatic
disengagement
cutout switch mechanism
(actuated by centrifugal
force) closed starter valve
automatically when outputshaft reaches
predetermined cutout speed
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Controls airflow to the pneumatic starter during engine
starting.
Operated pneumatically and solenoid- controlled.
Consists of two assemblies:
STARTER VALVE
Valve body assemblyPiston type pneumaticactuator assembly
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PNEUMATIC STARTING SYSTEM CIRCUIT
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ENGINE STARTING USING
AUXILIARY POWER UNIT
Pack valves and wing thermal anti-ice valves closed.
Applicable engine bleed valve open.
Bleed air isolation valve switch in AUTO.
Both air conditioning packs off.
The APU bleed valve ON.
Compressed air is supplied to the starter to rotate the N2
compressor of the engine.
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ENGINE STARTING USING
EXTERNAL AIR SOURCE
Depends on the external low pressure air source
connected to the ground pneumatic connection.
Procedure for starting is same as using the APU
except that bleed air valve for the applicable engine
must be opened manually if ac power is notavailable.
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ENGINE STARTING USING
ENGINE CROSS BLEED AIR
Can be done by using 8th-stage bleed air from the
operating engine.
The operating engine must operate at approximately80% N2 rpm.
The procedure for starting is the same as using theAPU.
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THE END