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OPERATING MANUAL
PSP 606
SECTION 5
AUXILIARY POWER UNIT (APU)
Subject
TABLE OF CONTENTS
Page
GENERAL
APU CONTROL
START SYSTEM
SHUTDOWN
IBLEED AIR SYSTEM
OIL SYSTEM
1
1
3
5
5
7
Figure
Number
LIST OF ILLUSTRATIONS
Title Page
1 APU Control Panels
2 APU Controls and Indicators
3 Auxiliary Battery Panel
4 APU Fault Indications
2
4
6
8
OPERATING MANUAL
PSP 606
SECTION 5
AUXILIARY POWER UNIT (APU)
GENERAL
The auxiliary power unit (APU) is a gas turbine engine which provides bleed air
for air conditioning and engine starting, and drive facilities to supply
electrical power. Except for the aircraft battery and fuel supply, the APU is
independent of other aircraft systems. It is mounted on a support skid
assembly, within an aluminum enclosure, in the rear fuselage behind the rear
pressure bulkhead. Access to the APU is by way of the rear equipment bay door.
Clean compressed air can be supplied for cabin and flight compartment air
conditioning on the ground or in the air, and for ground and in-flight engine
starting (for limitations on in-flight use of the APU, refer to the LIMITATIONS
section of the Airplane Flight Manual). Shaft power is used to drive a
generator to supply ground electrical power and in-flight standby power.
An APU control panel, located on the flight compartment overhead panel,
contains a combined power and fuel supply switch/light, FUEL ON/OFF, a single
START/STOP switch/light, a BLEED AIR supply switch/light, oil fault lights and
rpm and exhaust gas temperature (EGT) indicators. An APU fault annunciator
panel, located on the left side of the rear fuselage, contains fault indication
flags, an IND RESET pushbutton and a remote APU STOP pushbutton.
The APU has an independant fuel feed system which draws fuel from the right
main fuel tank. In addition, a tapping from the left engine fuel system
ensures that the supply of fuel to the APU is maintained during negative G
conditions (refer to Section 12, FUEL for details of APU fuel feed system).
Fire protection is from a single Firex bottle mounted on the fuselage structure
outside the APU enclosure (refer to Section 9, FIRE PROTECTION).
APU CONTROL (Figures 1 and 2)
An electronic control unit (ECU) mounted on the APU support monitors engine
speed, exhaust gas temperature, oil pressure and temperature and overcurrent
conditions during APU operation. Signals from sensors on the APU are relayed
through the ECU to the appropriate indicators on the APU CONTROL and APU FAULT
panels. The ECU also shuts down the APU under certain fault conditions (refer
to paragraph 4.).
Flight crew control and monitoring is provided by the APU control panel on the
flight compartment overhead panel. External shutdown control and fault finding
indicators are provided on the APU FAULT panel on the left side of the rear
fuselage (refer to Section 1, AIRCRAFT GENERAL, Figure 7).
SECTION 5
Page 1
Jun 12/86
canadair
chauencjer
OPERATING MANUAL
PSP 606
BLEED ADPTR FUEL APU START/
AIR OIL ON/OFF OIL STOP
©
®
APU FAULT
OVER OVER EGT
SPEED CURRENT HIGH o o o
PRESS LOW o
OIL
TEMP HIGH o
I GEN ADAPTER OIL
PRESS LOW TEMP HIGH o o
IND RESET APU STOP
0
EXTERNAL PANEL
(LEFT SIDE OF REAR FUSELAGE)
O
APU Control Panels
Figure 1 SECTION 5
Page 2
Feb 12/88
canadair
chanencjer
OPERATING MANUAL
PSP 606
An exhaust gas temperature indicator and an engine speed indicator are located
on the APU control panel. The exhaust gas temperature indicator is calibrated
in degrees Celsius and the engine speed indicator gives a readout in percentage
of maximum rpm. Fault lights and switch/lights are grouped above the APU
gauges.
The APU FAULT panel contains a STOP pushbutton and an IND RESET pushbutton.
The fault warning indicators are flags in the form of three white triangles in
a circle, on a black background. Flags indicate overspeed, overcurrent, high
exhaust gas temperature, low oil pressure, high oil temperature, generator
adapter low oil pressure and generator adapter high oil temperature. If the
fault which caused the indicator to show has been rectified, pushing the RESET
button causes the white triangles to rotate out of view.
START SYSTEM (Figures 2 and 3)
Electrical power for APU starting is provided by the aircraft 28-volt battery
or by an external dc ground power supply. The selection of power source is
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