Refer to 24-30 - Cirrus Aircraft

Refer to 24-30 - Cirrus Aircraft
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
DC GENERATION
1. DESCRIPTION
This section covers the systems to generate, regulate, control, and indicate DC electrical power. The DC
generation portion of the system includes the batteries, alternators (with internal rectifiers), and regulator.
A. DC Generation - Serials 1005 thru 1267 w/ Single Alternator (See Figure 24-301)
Primary power for the airplane is supplied by a 28-VDC negative-ground electrical system. The electrical power generation system consists of a 24-volt, 10-amp-hour battery, a 75-ampere alternator, a voltage regulator and an over-voltage protection system. The battery is an aviation grade, 12-cell leadacid type with non-spill vent caps. The battery is used for engine starting and as an emergency power
source in the event of alternator failure. The 75-ampere alternator provides constant charging current
for the battery and primary power to the aircraft electrical system during normal system operation. The
voltage regulator provides transient suppression and constant voltage regulation of the unfiltered alternator power. To protect sensitive instruments, the over-voltage protection system monitors the primary
power bus and automatically limits the peak voltage to 28.5 volts.
B. DC Generation - Serials 1005 thru 1267 w/ Dual Alternators (See Figure 24-302)
Primary power for the airplane is supplied by a 28-VDC negative-ground electrical system. The electrical power generation system consists of a 24-volt, 10-amp-hour battery, two alternators, and a master
Control Unit (MCU). The MCU contains an Alternator Control Unit (ACU) for each alternator, contactors for starter, battery, and ground power, a landing light relay, circuit protection for the circuit breaker
panel buses, and modules for other protection and annunciation functions. The battery is an aviation
grade, 12-cell lead-acid type with non-spill vent caps. The battery is used for engine starting and as an
emergency power source in the event of alternator failure.
Two rectified alternators provide constant charging current for the battery and primary power to the aircraft electrical system during normal system operation. The forward, belt-driven alternator is designated ALT 1. The aft, engine-driven alternator is designated ALT 2. Although each alternator produces
the same amount of power at a given rotational speed, ALT 1 rotates faster and is rated at 75 amperes
while ALT 2 is rated at 40 amperes. Paralleling circuits in the function modules balance alternator output so that, under normal operating conditions, ALT 1 provides 60% of the electrical power and ALT 2
provides the remaining 40%.
Each alternator's ACU provides transient suppression and constant voltage regulation of the alternator
output. To protect sensitive instruments, over-voltage circuits monitor each alternator's output and
automatically limit peak voltage to 28.5 volts. In the event an over-voltage or an overload condition
occurs, the associated ACU automatically opens the affected alternator's circuit breaker. With the
alternator off line, the associated ALT FAIL light illuminates, and the other alternator will provide 100%
of the electrical power requirements.
Should both alternators fail, the battery will supply system current and a discharge rate will be indicated on the ammeter. Under these conditions, depending on electrical system load, the LOW VOLTS
warning light will illuminate when system voltage drops below approximately 24.5 volts.
C. DC Generation - Serials 1268 thru 2015, 2016 & subs w/o Perspective Avionics (See Figure 24303)
Primary power for the airplane is supplied by a 28-VDC, negative-ground electrical system. The electrical power generation system consists of two alternators controlled by a Master Control Unit (MCU)
mounted on the left side of the firewall and two batteries for starting and electrical power storage.
Alternator 1 (ALT 1) is a belt-driven, internally rectified, 75-amp alternator mounted on the RH front of
the engine. Alternator 2 (ALT 2) is a gear-driven, internally rectified, 20-amp alternator mounted on the
accessory drive at the rear of the engine. ALT 1 is regulated to 28 volts and ALT 2 is regulated to 28.75
volts. The output from ALT 1 is connected to the main distribution bus in the MCU through an 80-amp
fuse. The output from ALT 2 is connected to the essential distribution bus in the MCU through a 40EFFECTIVITY:
All
24-30
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CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
amp fuse. Both alternators are self-exciting (not self-starting) and require battery voltage for field excitation in order to start up - for this reason, the batteries should not be turned off in flight.
Battery 1 (BAT 1) is an aviation grade 12-cell, lead-acid, 24-volt, 10-amp-hour battery mounted on the
right firewall. BAT 1 is charged from the main distribution bus in the MCU. Battery 2 (BAT 2) is composed of two 12-volt, 7-amp-hour, sealed, lead-acid batteries connected in series to provide 24 volts.
Both BAT 2 units are located in a vented, acid-resistant container mounted behind the aft cabin bulkhead (FS 222) below the parachute canister. BAT 2 is charged from the circuit breaker panel Essential
bus.
The Master Control Unit (MCU) is located on the left firewall. The MCU controls ALT 1, ALT 2, starter,
landing light, external power, and power generation functions. In addition to ALT 1 and ALT 2 voltage
regulation, the MCU also provides external power reverse polarity protection, alternator overvoltage
protection, as well as alternator fail and over-current annunciations. Power is distributed to the airplane
circuit panel buses through main and essential buses in the MCU. During normal operation, the alternators feed their respective distribution bus independently (ALT 1 feeds main distribution bus and ALT
2 feeds the essential distribution bus). The distribution buses are interconnected by two 50-amp fuses
and a diode. The diode prevents ALT 2 from feeding the main distribution bus. Additionally, since ALT2
/ essential distribution bus voltage is slightly higher than ALT 1 / main distribution bus voltage, ALT 1
will not feed the essential distribution bus unless ALT 2 fails.
D. DC Generation - Serials 2016 & subs w/ Perspective Avionics (See Figure 24-306)
During normal operation, the alternators feed their respective distribution bus independently (ALT 1
feeds Main Distribution Bus 1 and ALT 2 feeds Main Distribution Bus 2). The main distribution buses
are interconnected by an 80-amp (Serials 2016 thru 2240) or 60-amp (Serials 2241 & subs) fuse and
diode. The diode prevents ALT 2 from feeding Main Distribution Bus 1. Additionally, since ALT 2 voltage is slightly higher than ALT 1 voltage, bus voltage is further assured.
The alternators are three-phase AC generator type; each alternator has an internal rectifier. Each alternator uses two diodes for each phase to rectify the output. In addition, these diodes will block reverse
current. If a single output diode were to fail, the winding junction will be held to the output potential,
reducing the quantity of current the alternator can produce.
The alternators are regulated by the MCU and power the MCU via 6 AWG tin plated copper wires.
Alternator 1 is protected by an 100-amp fuse within the MCU while alternator 2 is protected by a 80amp fuse within the MCU. ALT 1 is connected to the Main Distribution Bus 1 and ALT 2 is connected to
the Main Distribution Bus 2. Each alternator system has its own 5-amp alternator circuit breaker
located in the circuit breaker panel. Each alternator is individually protected against overvoltage generation by the field control module, located within the MCU. ALT 1 is regulated to 28 volts and ALT 2 is
regulated to 28.75 volts.
Voltage output of each alternator is a function of engine RPM, alternator design, and load on the alternator. During low RPM operation, the alternator will require higher engine RPM to provide the same
voltage to increased electrical loads.
The drop off RPM for each alternator will change whenever the electrical system loads are altered from
nominal. Any time an alternator drops off line, a Crew Alerting System (CAS) message will appear on
the MFD. If an alternator drops off line due to low engine RPM, the alternator can be restarted by simply increasing engine RPM. When alternator 2 drops off line, alternator 1 will power the Essential Bus
through the Main Distribution Bus 1 in the MCU. When alternator 1 drops off line, alternator 2 will
power the Essential Bus through the Main Distribution Bus 2 in the MCU. For additional information
concerning power distribution, see Electrical Load Distribution. (Refer to 24-50)
E. DC Generation - Serials 1337 & subs w/ Single Alternator SRV (See Figure 24-304)
Primary power for the airplane is supplied by a 28-VDC, negative-ground electrical system. The electrical power generation system consists of an alternator controlled by a Master Control Unit (MCU)
mounted on the left side of the firewall and two batteries for starting and electrical power storage.
24-30
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EFFECTIVITY:
All
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
Alternator 1 (ALT 1) is a belt-driven, internally rectified, 75-amp alternator regulated to 28 volts, and
mounted on the RH front of the engine. Alternator power is routed into the MCU, where it is distributed
to the Main Distribution Bus and the Essential Distribution Bus. The alternator is regulated by a voltage
regulator within the MCU, and can be disconnected from the distribution bus system by the ALT 1
switch located on the pilot's bolster switch panel. The alternator is self-exciting (not self-starting) and
requires battery voltage for field excitation in order to start up - for this reason, the batteries should not
be turned off in flight.
Battery 1 (BAT 1) is an aviation grade 12-cell, lead-acid, 24-volt, 10-amp-hour battery mounted on the
right firewall. BAT 1 is charged from the main distribution bus in the MCU. Battery 2 (BAT 2) is composed of two 12-volt, 7-amp-hour, sealed, lead-acid batteries connected in series to provide 24 volts.
Both BAT 2 units are located in a vented, acid-resistant container mounted behind the aft cabin bulkhead (FS 222) below the parachute canister. BAT 2 is charged from the circuit breaker panel Essential
bus.
The Master Control Unit (MCU) is located on the left firewall. The MCU controls ALT 1, starter, landing
light, external power, and power generation functions. In addition to ALT 1 voltage regulation, the MCU
also provides external power reverse polarity protection, alternator overvoltage protection, as well as
alternator fail and over-current annunciations. Alternator power is distributed to the airplane circuit
panel buses through main and essential buses in the MCU. The distribution buses are interconnected
by two 50-amp fuses and a diode. The diode prevents BAT 2 from feeding the main distribution bus.
F.
DC Generation - Serials 1337 & subs w/ Dual Alternator SRV (See Figure 24-305)
Primary power for the airplane is supplied by a 28-VDC, negative-ground electrical system. The electrical power generation system consists of two alternators controlled by a Master Control Unit (MCU)
mounted on the left side of the firewall and two batteries for starting and electrical power storage.
Alternator 1 (ALT 1) is a belt-driven, internally rectified, 75-amp alternator mounted on the RH front of
the engine. Alternator 2 (ALT 2) is a gear-driven, internally rectified, 20-amp alternator mounted on the
accessory drive at the rear of the engine. ALT 1 is regulated to 28 volts and ALT 2 is regulated to 28.75
volts. The output from ALT 1 is connected to the main distribution bus in the MCU through an 80-amp
fuse. The output from ALT 2 is connected to the essential distribution bus in the MCU through a 40amp fuse. Both alternators are self-exciting (not self-starting) and require battery voltage for field excitation in order to start up - for this reason, the batteries should not be turned off in flight.
Battery 1 (BAT 1) is an aviation grade 12-cell, lead-acid, 24-volt, 10-amp-hour battery mounted on the
right firewall. BAT 1 is charged from the main distribution bus in the MCU. Battery 2 (BAT 2) is composed of two 12-volt, 7-amp-hour, sealed, lead-acid batteries connected in series to provide 24 volts.
Both BAT 2 units are located in a vented, acid-resistant container mounted behind the aft cabin bulkhead (FS 222) below the parachute canister. BAT 2 is charged from the circuit breaker panel Essential
bus.
The Master Control Unit (MCU) is located on the left firewall. The MCU controls ALT 1, ALT 2, starter,
landing light, external power, and power generation functions. In addition to ALT 1 and ALT 2 voltage
regulation, the MCU also provides external power reverse polarity protection, alternator overvoltage
protection, as well as alternator fail and over-current annunciations. Power is distributed to the airplane
circuit panel buses through main and essential buses in the MCU. During normal operation, the alternators feed their respective distribution bus independently (ALT 1 feeds main distribution bus and ALT
2 feeds the essential distribution bus). The distribution buses are interconnected by two 50-amp fuses
and a diode. The diode prevents ALT 2 from feeding the main distribution bus. Additionally, since ALT2
/ essential distribution bus voltage is slightly higher than ALT 1 / main distribution bus voltage, ALT 1
will not feed the essential distribution bus unless ALT 2 fails.
EFFECTIVITY:
Serials 1337 & subs w/ Dual Alternator SRV
24-30
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CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
ALT RELAY
MASTER CONTROL UNIT
(MCU)
(SEE SHEET 2)
ALT SWITCH
LOW VOLTS
25A
15A
15A
LANDING LIGHT
MAIN BUS 1
25A
NON-ESSENTIAL
MAIN BUS 2
25A
STANDBY VACUUM
AVIONICS
SEE VACUUM SYSTEM
AVIONICS
AVIONICS
STARTER RELAY
CONVENIENCE
POWER 12VDC
PITOT HT./
COOLING FAN
FLAPS
COM 2
GPS 2
MFD
ADF
COM I
AVIONICS
ESSENTIAL
AUXILIARY PWR. 28VDC
AVIONICS
NON-ESSENTIAL
NON-ESSENTIAL
STANDBY VACUUM
GPS 1
ENCODER/TRANS
AUDIO PANEL
STORMSCOPE
DME
NAV LIGHTS
CABIN FLOOD LIGHTS
STROBE LIGHTS
AUTO PILOT
MAIN BUS 1
MAIN BUS 2
FUEL PUMP
INST. LIGHTS
PITCH TRIM
ESSENTIAL
HSI
ANNUN. POWER
TURN COORD.
ENGINE INST.
ALTERNATOR
ROLL TRIM
ESSENTIAL 2
ESSENTIAL I
CIRCUIT BREAKER PANEL
NOTE
Earlier serials have fuses in place of circuit breakers.
Serials 1005 thru 1267.
SR20_MM24_1316B
Figure 24-301
Single Alternator Electrical System Schematic - Serials 1005 thru 1267 (Sheet 1 of 2)
24-30
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15 Jun 2010
EFFECTIVITY:
Serials 1005 thru 1267
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
CIRCUIT BREAKER
PANEL
(SEE SHEET 1)
+ 28V
ALT SWITCH
LANDING
LIGHT
25
POWER
BUS
BAR
25
LANDING
LIGHT
RELAY
25
15
LANDING
LIGHT
SWITCH
15
ALT
RELAY
ALT 1
BATTERY
RELAY
BAT
EXTERNAL
POWER
RECEPTACLE
GND
POWER
RELAY
FLD
ACU
CURRENT
SENSOR
+
STARTER
RELAY
-
M
STARTER
MOTOR
FUNCTION
MODULE
+ 28V
IGNITION
SWITCH
STANDBY
VACUUM
STUD (MCU)
MCU
VOLTS
AMPS
+
V
O
L
T
A
M
P
-
ANNUNC.
LOW VOLTS
BATTERY SWITCH
+ 28V
+
-
BATTERY
Serials 1005 thru 1267.
SR20_MM24_1313B
Figure 24-301
Single Alternator Electrical System Schematic - Serials 1005 thru 1267 (Sheet 2 of 2)
EFFECTIVITY:
Serials 1005 thru 1267
24-30
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15 Jun 2010
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
ALT 2 RELAY
MASTER CONTROL UNIT
(MCU)
(SEE SHEET 2)
ALT 2 SWITCH
ALT 1 RELAY
ALT 1 SWITCH
25A
15A
ALT 1 FAIL LED
15A
ALT 2 FAIL LED
MAIN BUS 1
25A
NON-ESSENTIAL
MAIN BUS 2
25A
LANDING LIGHT
STANDBY VACUUM
LOW VOLTS
AVIONICS
SEE VACUUM SYSTEM
AVIONICS
AVIONICS
STANDBY VACUUM
CONVENIENCE
POWER 12VDC
PITOT HT./
COOLING FAN
FLAPS
COM 2
GPS 2
MFD
ADF
COM I
AVIONICS
ESSENTIAL
AUXILIARY PWR. 28VDC
AVIONICS
NON-ESSENTIAL
NON-ESSENTIAL
STARTER RELAY
GPS 1
ENCODER/TRANS
AUDIO PANEL
STORMSCOPE
DME
NAV LIGHTS
CABIN FLOOD LIGHTS
STROBE LIGHTS
ESSENTIAL 2
MAIN BUS 1
MAIN BUS 2
FUEL PUMP
AUTO PILOT
INST. LIGHTS
PITCH TRIM
ROLL TRIM
ESSENTIAL
HSI
ANNUN. POWER
TURN COORD.
ENGINE INST.
ALTERNATOR 1
ALTERNATOR 2
ESSENTIAL I
CIRCUIT BREAKER PANEL
Serials 1005 thru 1267.
SR20_MM24_1317B
Figure 24-302
Dual Alternator Electrical System Schematic - Serials 1005 thru 1267 (Sheet 1 of 2)
24-30
Page 6
15 Jun 2010
EFFECTIVITY:
Serials 1005 thru 1267
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
CIRCUIT BREAKER
PANEL
(SEE SHEET 1)
ALT 1 FAIL LED
2
ANNUNC
5
ALT 1
5
ALT 2
ALT 2 FAIL LED
ALT 1
RELAY
ALT 2
RELAY
ALT 2 SWITCH
ALT 1 SWITCH
ACU
1
POWER
BUS
BAR
25
LANDING
LIGHT
25
FLD
25
BAT
80A
15
ALT 1
ALT 2
ALT 1 +
ALT 2 +
ALT -
FUNCTION
MODULE/
CURRENT
SENSOR
80A
15
LANDING
LIGHT
RELAY
LANDING
LIGHT
SWITCH
BAT
FLD
EXTERNAL
POWER
RECEPTACLE
ACU
2
GND
POWER
RELAY
BATTERY
RELAY
FUNCTION
MODULE/
CURRENT
SENSOR
+
-
M
STARTER
RELAY
STARTER
MOTOR
+ 28V
IGNITION
SWITCH
STANDBY
VACUUM
STUD (MCU)
MCU
ANNUNC.
LOW VOLTS
AMMETER
SELECTOR
SWITCH
+28 V
VOLTS
AMPS
+
V
O
A
+
M
P
L
T
BATTERY SWITCH
-
-
BATTERY
Serials 1005 thru 1267.
SR20_MM24_1314B
Figure 24-302
Dual Alternator Electrical System Schematic - Serials 1005 thru 1267 (Sheet 2 of 2)
EFFECTIVITY:
Serials 1005 thru 1267
24-30
Page 7
15 Jun 2010
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
ALT 1
RELAY
VOLT REG
F
ALT 1
ALT 1
SWITCH
EXTERNAL
POWER
15A
LANDING LIGHT
SWITCH
MAIN DIST
125A
25A
25A
BAT 1
SWITCH
BAT 1
LANDING
LIGHT
B
100A
25A
25A
STARTER
F
ALT 2
B
OIL
ALT 1
ALT 2
LOW
VOLTS
PITOT
HEAT
40A
50A
50A
ESSENTIAL
DIST
FUEL
VOLT REG
25A
25A
MASTER CONTROL UNIT
BAT 2
30A
BAT 2 SWITCH
FUEL PUMP
GPS 2
COM 2
XPNDER
XM/WX
ANN/ENG IND
TRN CRD #2
TRN CRD #1
ATTITUDE #2
ESSENTIAL
TRAFF/TAWS
MAIN BUS 2
AVIONICS NON-ESSENTIAL
CIRCUIT BREAKER PANEL
PFD #2
ALT 1
CABIN LTS
PFD #1
2A
2A
STALL WARN
BATTERY 2
2A
MFD
ATT
GYRO
ATTITUDE #1
ALT 2
AUDIO PANEL
FUEL QUANTITY
REC/INST LTS
PITCH TRIM
ROLL TRIM
A/C 2
ICE PROTECT
START RELAY
PITOT/FAN
12V/ANR
STROBE LTS
NAV LTS
AVIONICS
ESSENTIAL
MAIN BUS 1
AVIONICS
NON-ESSENTIAL
ESS POWER
AUTOPILOT
ALT 2
SWITCH
AVIONICS
ESSENTIAL RELAY
AVIONICS
COM 1
GPS 1
FLAPS
FAN
COMPR/CTRL
AVIONICS
NON-ESSENTIAL
RELAY
AVIONICS
SWITCH
NOTE
Serials 1268 thru 1581: 80A fuse.
Serials 1268 thru 1581: 100A fuse.
Serials 1633, 1639 & subs w/ optional Blower Fan installed.
SR20_MM24_1599E
Figure 24-303
Electrical System Schematic - Serials 1268 & subs w/o SRV & w/o Perspective Avionics
24-30
Page 8
15 Jun 2010
EFFECTIVITY:
Serials 1268 & subs w/o SRV & w/o Perspective Avionics
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
ALT 1
RELAY
VOLT REG
F
EXTERNAL
POWER
15A
LANDING LIGHT
SWITCH
MAIN DIST
125A
25A
25A
BAT 1
SWITCH
BAT 1
LANDING
LIGHT
B
100A
ALT 1
SWITCH
ALT 1
25A
25A
STARTER
OIL
ALT 1
LOW
VOLTS
PITOT
HEAT
50A
50A
25A
ESSENTIAL
DIST
FUEL
25A
MASTER CONTROL UNIT
BAT 2
30A
BAT 2 SWITCH
FUEL PUMP
GPS 2
COM 2
XPNDER
XM/WX
ANN/ENG IND
TRN CRD #2
TRN CRD #1
ATTITUDE #2
ESSENTIAL
TRAFF/TAWS
MAIN BUS 2
AVIONICS NON-ESSENTIAL
CIRCUIT BREAKER PANEL
PFD #2
ALT 1
CABIN LTS
PFD #1
2A
STALL WARN
BATTERY 2
2A
MFD
ATTITUDE #1
ALT 2
AUDIO PANEL
A/C 2
FUEL QUANTITY
REC/INST LTS
PITCH TRIM
ROLL TRIM
START RELAY
PITOT/FAN
12V/ANR
STROBE LTS
NAV LTS
AVIONICS
ESSENTIAL
MAIN BUS 1
AVIONICS
NON-ESSENTIAL
ESS POWER
AUTOPILOT
AVIONICS
ESSENTIAL RELAY
AVIONICS
COM 1
GPS 1
FLAPS
FAN
COMPR/CTRL
AVIONICS
NON-ESSENTIAL
RELAY
AVIONICS
SWITCH
NOTE
Serials 1337 thru 1581: 80A fuse.
Serials 1337 thru 1581: 100A fuse.
Serials 1633, 1639 & subs w/ optional Blower Fan installed.
SR20_MM24_1733D
Figure 24-304
Electrical System Schematic - Serials 1337 & subs w/ Single Alternator SRV
EFFECTIVITY:
Serials 1337 & subs w/ Single Alternator SRV
24-30
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CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
ALT 1
RELAY
VOLT REG
F
EXTERNAL
POWER
15A
LANDING LIGHT
SWITCH
MAIN DIST
125A
25A
25A
BAT 1
SWITCH
BAT 1
LANDING
LIGHT
B
100A
ALT 1
SWITCH
ALT 1
25A
25A
STARTER
F
ALT 2
B
OIL
ALT 1
ALT 2
LOW
VOLTS
PITOT
HEAT
40A
50A
50A
ESSENTIAL
DIST
FUEL
VOLT REG
25A
25A
MASTER CONTROL UNIT
BAT 2
30A
BAT 2 SWITCH
FUEL PUMP
GPS 2
COM 2
XPNDER
XM/WX
ANN/ENG IND
TRN CRD #2
TRN CRD #1
ATTITUDE #2
ESSENTIAL
TRAFF/TAWS
MAIN BUS 2
AVIONICS NON-ESSENTIAL
CIRCUIT BREAKER PANEL
PFD #2
ALT 1
CABIN LTS
PFD #1
2A
STALL WARN
BATTERY 2
2A
MFD
ATTITUDE #1
ALT 2
AUDIO PANEL
A/C 2
FUEL QUANTITY
REC/INST LTS
PITCH TRIM
ROLL TRIM
START RELAY
PITOT/FAN
12V/ANR
STROBE LTS
NAV LTS
AVIONICS
ESSENTIAL
MAIN BUS 1
AVIONICS
NON-ESSENTIAL
ESS POWER
AUTOPILOT
ALT 2
SWITCH
AVIONICS
ESSENTIAL RELAY
AVIONICS
COM 1
GPS 1
FLAPS
FAN
COMPR/CTRL
AVIONICS
NON-ESSENTIAL
RELAY
AVIONICS
SWITCH
NOTE
Serials 1337 thru 1581: 80A fuse.
Serials 1337 thru 1581: 100A fuse.
Serials 1633, 1639 & subs w/ optional Blower Fan installed.
SR20_MM24_1734D
Figure 24-305
Electrical System Schematic - Serials 1337 & subs w/ Dual Alternator SRV
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Page 10
15 Jun 2010
EFFECTIVITY:
Serials 1337 & subs w/ Dual Alternator SRV
AIRPLANE MAINTENANCE MANUAL
LANDING
LIGHT
100A
F ALT 1 B
ALT 1
RELAY
7.5A
MAIN DIST BUS 1
VOLT REG
ALT 1
SWITCH
EXTERNAL
POWER RELAY
EXTERNAL
POWER
125A
BAT 1
MODEL SR20
BAT 1
RELAY
BAT 1
SWITCH
LANDING LIGHT
SWITCH
30A
30A
30A
50A
80A
ESSENTIAL DIST BUS
CIRRUS
50A
STARTER
STARTER
RELAY
STARTER
SWITCH
80A
F ALT 2 B
MAIN DIST BUS 2
50A
30A
30A
30A
30A
30A
VOLT REG
MASTER CONTROL UNIT
AVIONICS
FAN 2
GPS NAV
GIA 2
COM 2
AHRS 2/
ADC 2
FUEL
PUMP
PFD #2
MAIN BUS 1
MAIN BUS 3
8A
EVS
CAMERA
12V DC
OUTLET
MFD #1
ALT 2
ENGINE
INSTR
STALL
WARNING
ROLL
TRIM
PITCH
TRIM
ADC 1
AHRS 1
STDBY
ATTD #1
PFD #1
AVIONICS
STDBY
ATTD #2
MFD #2
CABIN LIGHTS
FUEL QTY
AP SERVOS
KEYPADS /
AP CTRL
ESSENTIAL
POWER
BAT 2
GPS NAV
GIA 1
COM 1
20A
AVIONICS BUS
STARTER
AVIONICS
FAN 1
RECOG
LIGHTS
NAV
LIGHTS
STROBE
LIGHTS
PITOT
HEAT
FLAPS
MAIN BUS 2
20A
NON-ESSENTIAL BUS
A/C BUS 2
8A
CABIN AIR
CONTROL
CABIN
FAN
ESSENTIAL BUS 2
ALT 1
ESSENTIAL BUS 1
A/C BUS 1
ALT 2
SWITCH
DME / ADF
AUDIO
PANEL
WEATHER
XPONDER
TRAFFIC
CIRCUIT BREAKER PANEL
30A
BAT 2
AVIONICS
SWITCH
BAT 2
SWITCH
AVIONICS
NON-ESSENTIAL
RELAY
Serials 2016 thru 2064 w/ Perspective Avionics.
SR20_MM24_2900A
Figure 24-306
Electrical System Schematic - Serials 2016 thru 2064 w/ Perspective Avionics (Sheet 1 of 3)
EFFECTIVITY:
Serials 2016 thru 2064 w/ Perspective Avionics
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AIRPLANE MAINTENANCE MANUAL
LANDING
LIGHT
100A
F ALT 1 B
ALT 1
RELAY
7.5A
MAIN DIST BUS 1
VOLT REG
ALT 1
SWITCH
EXTERNAL
POWER RELAY
EXTERNAL
POWER
125A
BAT 1
MODEL SR20
BAT 1
RELAY
BAT 1
SWITCH
LANDING LIGHT
SWITCH
30A
30A
30A
50A
80A
ESSENTIAL DIST BUS
CIRRUS
50A
STARTER
STARTER
RELAY
STARTER
SWITCH
80A
F ALT 2 B
MAIN DIST BUS 2
50A
30A
30A
30A
30A
30A
VOLT REG
MASTER CONTROL UNIT
STARTER
AVIONICS
FAN 1
RECOG
LIGHTS
NAV
LIGHTS
STROBE
LIGHTS
PITOT
HEAT
FLAPS
8A
AVIONICS
FAN 2
GPS NAV
GIA 2
COM 2
AHRS 2/
ADC 2
FUEL
PUMP
PFD #2
MAIN BUS 1
CABIN
FAN
ALT 2
ENGINE
INSTR
STALL
WARNING
ROLL
TRIM
PITCH
TRIM
ADC 1
AHRS 1
STDBY
ATTD #1
PFD #1
AVIONICS
STDBY
ATTD #2
MFD #2
CABIN LIGHTS
/ OXYGEN
FUEL QTY
AP SERVOS
KEYPADS /
AP CTRL
CABIN AIR
CONTROL
ESSENTIAL
POWER
BAT 2
GPS NAV
GIA 1
COM 1
20A
AVIONICS BUS
A/C COMPR
MAIN BUS 2
20A
NON-ESSENTIAL BUS
A/C BUS 2
8A
ESSENTIAL BUS 2
EVS
CAMERA
12V DC
OUTLET
MFD #1
ALT 1
ESSENTIAL BUS 1
A/C BUS 1
A/C COND
MAIN BUS 3
ALT 2
SWITCH
DME / ADF
AUDIO
PANEL
WEATHER
/DATA LINK
XPONDER
TRAFFIC
CIRCUIT BREAKER PANEL
30A
BAT 2
AVIONICS
SWITCH
BAT 2
SWITCH
AVIONICS
NON-ESSENTIAL
RELAY
Serials 2065 thru 2240 w/ Perspective Avionics.
SR20_MM24_3359B
Figure 24-306
Electrical System Schematic - Serials 2065 thru 2240 w/ Perspective Avionics (Sheet 2 of 3)
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EFFECTIVITY:
Serials 2065 thru 2240 w/ Perspective Avionics
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
LANDING
LIGHT
100A
F ALT 1 B
ALT 1
RELAY
7.5A
VOLT REG
ALT 1
SWITCH
MAIN DIST BUS 1
CIRRUS
EXTERNAL
POWER RELAY
EXTERNAL
POWER
LANDING LIGHT
SWITCH
30A
30A
30A
ESSENTIAL DIST BUS
125A
50A
BAT 1
RELAY
BAT 1
SWITCH
60A
STARTER
STARTER
RELAY
50A
50A
STARTER
SWITCH
5A
60A
F ALT 2 B
MAIN DIST BUS 2
BAT 1
30A
30A
30A
30A
30A
VOLT REG
MASTER CONTROL UNIT
CABIN
FAN
8A
AVIONICS
FAN 2
GPS NAV
GIA 2
COM 2
AHRS 2/
ADC 2
FUEL
PUMP
PFD #2
MAIN BUS 1
A/C COMPR
UAT
RECOG
LIGHTS
EVS
CAMERA
12V DC
OUTLET
MFD #1
ALT 2
ENGINE
INSTR
STALL
WARNING
ROLL
TRIM
PITCH
TRIM
GPS NAV
GIA 1
COM 1
ADC 1
AHRS 1
STDBY
ATTD #1
PFD #1
AVIONICS
ICE
LIGHTS
STDBY
ATTD #2
MFD #2
CABIN
LIGHTS
FUEL QTY
AP SERVOS
KEYPADS
/ AP CTRL
CABIN AIR
CONTROL
ESSENTIAL
POWER
BAT 2
20A
AVIONICS BUS
MAIN BUS 3
ALT 1
STARTER
AVIONICS
FAN 1
NAV
LIGHTS
STROBE
LIGHTS
PITOT
HEAT
FLAPS
1
8A
ESSENTIAL BUS 2
A/C COND
ESSENTIAL BUS 1
CONV
LIGHTS
MAIN BUS 2
20A
NON-ESSENTIAL BUS
A/C BUS 2
A/C BUS 1 CONS
ALT 2
SWITCH
DME / ADF
AUDIO
PANEL
DATA LINK/
WEATHER
XPONDER
TRAFFIC
CIRCUIT BREAKER PANEL
30A
NOTE
1
BAT 2
Serials 2303 & subs.
BAT 2
SWITCH
AVIONICS
SWITCH
AVIONICS
NON-ESSENTIAL RELAY
Serials 2241 & subs w/ Perspective Avionics.
SR20_MM24_3636C
Figure 24-306
Electrical System Schematic - Serials 2241 & subs w/ Perspective Avionics (Sheet 3 of 3)
EFFECTIVITY:
Serials 2241 & subs w/ Perspective Avionics
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AIRPLANE MAINTENANCE MANUAL
MODEL SR20
G. Alternator 1 (See Figure 24-307)
Alternator 1 is mounted directly to the front, LH side of the engine and is used in all electrical configurations.
Alternator 1 is a 75-amp belt-driven alternator. Alternator 1 has sufficient capacity to power the entire
aircraft electrical load and charge the battery during normal system operation. The alternator and battery are designed to function in parallel or independently and can be alternately connected to the primary bus. Alternator 1 will continue to generate electrical power in the case of battery failure or
malfunction. Alternator 1 is self-exciting, not self-starting. The battery must energize Alternator 1
before it can produce electrical power.
H. Alternator 2 (See Figure 24-308)
Serials 1005 thru 1267: The optional dual alternator system adds a 40-amp engine-driven alternator 2
to the single alternator system. An alternator switch, ammeter switch, circuit breaker, function module,
alternator fail lights, and alternator relay is also added in this configuration. Alternator 2 is mounted
directly to the aft engine accessory pad.
On the optional dual alternator system, alternator 1 produces approximately 60% of the system voltage
and alternator 2 produces approximately 40%. If alternator 1 fails during heavy loading, it may be necessary to shed electrical load to prevent over-burdening alternator 2. The alternator fail lights are
located to the immediate right of the annunciator panel. The lights provide warning of a failed or inoperative alternator. If an alternator is not providing adequate proportional power, the appropriate alternator fail LED will illuminate. In addition, both lights will illuminate during a battery discharge situation
(approximately a 3-amp draw).
Serials 1268 & subs w/o single alternator SRV: Alternator 2 is a 20-amp engine-driven alternator
mounted directly to the aft engine accessory pad. Alternator 2 supplies electrical power to the essential
bus through a 25-amp circuit breaker located in the MCU.
I.
Master Control Unit (MCU) (See Figure 24-309)
The MCU is an integrated component which ensures proper electrical output over the entire temperature and RPM range of the alternator system by regulating and distributing alternator output. The MCU
is mounted to the firewall, directly behind the engine.
(1)
Master Control Unit - Serials 1005 thru 1267
The MCU used in the single alternator system contains a landing light relay, ammeter transducer, alternator control unit (ACU), three 25-amp distribution feeder fuses, buses, and contactors for the alternator, start, master battery, and ground power circuits.
The MCU used in the optional dual alternator system contains a landing light relay, 15-amp landing light circuit breaker, 15-amp auxiliary power circuit breaker, two ACUs, two function modules,
three 25-amp distribution feeder circuit breakers, buses, and contactors for the start, master battery, and ground power circuits.
Note:
The MCU on these airplanes is not field repairable and must be replaced if faulty.
The MCU will trip the alternator circuit breaker(s) whenever there is more than 6-10 amps
reverse current. The pilot has access to the alternator circuit breaker(s), which are located in the
circuit breaker panel, during flight. If the system is generating more than 31.75 ± 0.5 V, the corresponding alternator circuit breaker will open, preventing further power generation by that alternator. The other alternator will regulate at a higher rate, 29.0 +0.25, -0.5 V during the overvoltage.
After the circuit breaker opens, the other alternator will provide 100% of the load at the nominal
voltage.
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The MCU contains a current sensor in the battery bus, this current sensor sends a signal to the
ammeter (battery charge or discharge). The ammeter only indicates a discharge when the electrical draw on the system exceeds the quantity of power generated by system. In the dual alternator system, the ammeter will only indicate a discharge when the ammeter select switch is in
EFFECTIVITY:
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CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
the BATT position and the electrical draw on the system exceeds the quantity of power generated by system. Diodes in the alternator(s) block reverse current making negative current indication unnecessary. The current value displayed by the ammeter corresponds directly to the
quantity of power generated by the alternator system. When the ammeter select switch is in the
ALT 1 or ALT 2 position (dual alternator system only), the ammeter drives will only allow the
ammeter to display a positive current value because of the diodes within the alternator block.
The master switch arrangement, located in the pilot's bolster contains the battery, alternator 1,
and alternator 2 control switches. Each switch disconnects the associated device from the primary bus. The switches are located in a side-by-side arrangement and are labeled as to their
function. The BATT master switch, when closed, connects battery 1 to the primary bus. This
switch activates a contactor within the MCU, providing the ability to connect and disconnect battery power from the aircraft. The battery switch controls a contactor, which isolates battery 1,
while the alternator switch removes field excitation from the alternator thereby isolating the primary bus.
Six buses are powered from the MCU. These buses are designed to ensure essential flight and
avionics systems remain powered during a malfunction of any one of the buses. Three bus wires
run from the MCU, through the firewall, and to the circuit breaker panel. Three bus wires in the
MCU are overload protected by fuses and circuit breakers. Three buses are used to power the
majority of aircraft loads and supply power to the circuit breaker panel. The fourth bus is for the
landing light. The fifth is the clock bus which is fused at 5 amperes and is the only bus powered
directly from battery 1 and is not controlled by the master switch arrangement. The clock bus
fuse is externally removable for long term storage situations to prevent battery drain. The sixth
bus is for the standby vacuum pump.
Alternator power flows from the alternator into the MCU. Inside the MCU is where the ACU regulates alternator output. The ACU (voltage regulator) provides transient suppression and constant
voltage regulation of unfiltered alternator power. To protect sensitive instruments, the over-voltage protection system monitors the primary power bus and automatically limits peak voltage to
approximately 31.75 volts. During sustained over-voltage and under-voltage periods, the overvoltage system provides a warning to the pilot. The ACU will cause the alternator circuit breaker
to open in cases of reverse current, field output overloads, and overvoltage. In the event an
over-voltage condition occurs, the ACU automatically removes alternator field current to shut
down the alternator. The ACU has been integrated into the MCU case, for durability and reliability.
(2)
Master Control Unit 100 and 120 - Serials 1268 thru 1581
The MCU controls alternator 1, alternator 2 (Serials w/ dual alternators), starter, landing light,
external power, and the power generation system annunciation. The MCU provides protection
for external power reverse polarity and alternator overvoltage situations. The MCU also provides
low voltage annunciation and an overload annunciation for ALT 1 and ALT 2 (Serials w/ dual
alternators) fail annunciators in the instrument panel.
The bus structure of the MCU and the circuit breaker panel allows all power devices to feed into
the Essential Bus during emergencies. This action is automatic and does not require pilot intervention. The Main and Essential Buses are separated via diodes which allow the Main Bus to
feed into the Essential Bus during failures of Alternator 2 (Serials w/ dual alternators) or Battery
2. The MCU regulates Alternator 1 to 28 VDC, while Alternator 2 (Serials w/ dual alternators) is
regulated to 28.75 VDC which ensures the diode separates the buses during normal operation.
The MCU used on this airplane contains a landing light relay, battery relay, ground power relay,
starter relay, ammeter transducer, 15-amp landing light circuit breaker, two buses (one essential
and one non-essential), two field control modules, three current sensors, and five 25-amp distribution feeder circuit breakers.
The pilot has access to the alternator circuit breaker(s), which are located in the circuit breaker
panel, during flight. If the system is generating more than 31.75 ± 0.25 V, the corresponding
alternator circuit breaker will open, preventing further power generation by that alternator.
EFFECTIVITY:
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CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
The MCU contains a current sensor in the battery bus, this current sensor sends a signal to the
ammeter (battery charge or discharge). The ammeter will only indicate a discharge when the
ammeter select switch is in the BATT position and the electrical draw on the system exceeds the
quantity of power generated by the system. Diodes in the alternators block reverse current making negative current indication unnecessary. The current value displayed by the ammeter corresponds directly to the quantity of power generated by the alternator system. When the ammeter
select switch is in the ALT 1 or ALT 2 (Serials w/ dual alternators) position, the ammeter drives
will only allow the ammeter to display a positive current value because of the diodes within the
alternator block.
The master switch arrangement, located in the pilot's bolster contains battery 1, battery 2, alternator 1, and alternator 2 (Serials w/ dual alternators) control switches. Each switch disconnects
the associated device from the corresponding bus. The switches are located in a side-by-side
arrangement and are labeled as to their function. The BAT 2 switch, when closed, connects battery 2 to the Essential Bus. This switch activates a relay located next to BAT 2, providing the
ability to connect and disconnect battery 2 from the aircraft.
Seven power distribution buses with associated protection devices are located in the MCU.
These buses are designed to ensure essential flight and avionics systems remain powered
during a malfunction of any one of the buses. Five bus wires run from the MCU, through the firewall, and to the circuit breaker panel for overload protection by fuses or circuit breakers. The five
buses are used to power the majority of aircraft loads and supply power to the circuit breaker
panel. Three buses are used as distribution feeders from the Main Distribution Bus. Two buses
are used as distribution feeders from the Essential Distribution Bus. One bus is used to power
the landing light directly from the Main Distribution Bus through a 15 amp circuit breaker. One
bus is used to power the clock which is fused at 5 amperes and is the only bus powered directly
from battery 1 and is not controlled by master switch arrangement. The clock bus fuse is externally removable for long term storage situations to prevent battery drain. On PFD equipped airplanes, the clock bus is not used.
Alternator power flows from alternator(s) into the MCU. Inside the MCU is where the field control
module regulates alternators output. Each field control module provides transient suppression
and constant voltage regulation of unfiltered alternator power. To protect sensitive instruments,
the over-voltage protection system monitors the primary power bus and automatically limits peak
voltage to approximately 31.75 volts. During sustained over-voltage periods, the over-voltage
system provides a warning to the pilot. Each field control module will cause the corresponding
alternator circuit breaker to open in cases of field output overloads, and overvoltage. In the event
an over-voltage condition occurs, the corresponding field control module automatically removes
alternator field current to shut down the corresponding alternator. Each field control module has
been integrated into the MCU case, for durability and reliability.
(3)
Master Control Unit 130 and 140 - Serials 1582 & subs
The MCU 130 (Serials w/o Perspective) and 140 (Serials w/ Perspective) controls alternator 1,
alternator 2 (Serials w/ dual alternators), starter, landing light, and external power. The MCU provides protection for external power reverse polarity and alternator overvoltage situations. The
bus structure of the MCU and the circuit breaker panel allows all power devices to feed into the
Essential Bus during emergencies. This action is automatic and does not require pilot intervention.
MCU 130: The Main and Essential Buses are separated via diodes which allow the Main Bus to
feed into the Essential Bus during failures of Alternator 2 (Serials w/ dual alternators) or Battery
2. The MCU used on this airplane contains a landing light relay, battery relay, ground power
relay, starter relay, 15-amp landing light circuit breaker, two buses (one essential and one nonessential), two field control modules, two (Serials w/ single alternator) or three (Serials w/ dual
alternators) current shunts, and seven 25-amp distribution feeder circuit breakers.
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MCU 140: The Main Distribution Bus 1 and Main Distribution Bus 2 are separated via a diode
which allows the Main Bus 1 to feed into Main Bus 2 during failures of Alternator 2. The MCU
EFFECTIVITY:
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CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
used on this airplane contains a landing light relay, battery relay, ground power relay, starter
relay, 7.5-amp landing light fuse, three buses (one essential and two non-essential), two field
control modules, three current shunts, and eight 30-amp distribution feeder fuses.
The MCU regulates Alternator 1 to 28 VDC. while Alternator 2 (Serials w/ dual alternators) is
regulated to 28.75 VDC which ensures the diode separates the buses during normal operation.
The pilot has access to the alternator circuit breaker(s), which are located in the circuit breaker
panel, during flight. If the system is generating more than 31.75 ± 0.25 V, the corresponding
alternator circuit breaker will open, preventing further power generation by that alternator.
The MCU contains a current shunt in the battery bus. This current shunt sends a signal to the
data acquisition unit (Serials w/o Perspective) or the GEA 71 engine airframe unit (Serials w/
Perspective). Diodes in the alternators block reverse current making negative current indication
unnecessary. The current value displayed by the ammeter (Serials w/o Perspective) or MFD
(Serials w/ Perspective) corresponds directly to the quantity of power generated by the alternator system.
The master switch arrangement, located in the pilot's bolster contains battery 1, battery 2, alternator 1, and alternator 2 (Serials w/ dual alternators) control switches. Each switch disconnects
the associated device from the corresponding bus. The switches are located in a side-by-side
arrangement and are labeled as to their function. The BAT 2 switch, when closed, connects battery 2 to the Essential Bus. This switch activates a relay located next to BAT 2, providing the
ability to connect and disconnect battery 2 from the aircraft.
Nine (Serials 2016 thru 2240) or ten (Serials 2241 & subs) power distribution buses with associated protection devices are located in the MCU. The buses are designed to ensure essential
flight and avionics systems remain powered during a malfunction of any one of the buses.
MCU 130: Seven bus wires run from the MCU, through the firewall, and to the circuit breaker
panel for overload protection by fuses or circuit breakers. The seven buses are used to power
the majority of aircraft loads and supply power to the circuit breaker panel. Five buses are used
as distribution feeders from the Main Distribution Bus. Two buses are used as distribution feeders from the Essential Distribution Bus. One bus is used to power the landing light directly from
the Main Distribution Bus through a 15 amp circuit breaker. One bus was used to power the
clock which was fused at 5 amperes. On PFD equipped airplanes, the clock bus is not used.
MCU 140: Eight bus wires run from the MCU, through the firewall, and to the circuit breaker
panel for overload protection by fuses or circuit breakers. The eight buses are used to power the
majority of aircraft loads and supply power to the circuit breaker panel. Three buses are used as
distribution feeders from the Main Distribution Bus 1. Three buses are used as distribution feeders from the Main Distribution Bus 2. Two buses are used as distribution feeders from the
Essential Distribution Bus. One bus is used to power the landing light directly from the Main Distribution Bus 1 through a 7.5 amp fuse.
Serials 22-2241 & subs: One bus is used to power the constant power devices including the
interface between the CAPS and the ELT system which is fused at 5 amperes and is not controlled by master switch arrangement.
Alternator power flows from alternator(s) into the MCU. Inside the MCU is where the field control
module regulates alternator(s) output. Each field control module provides transient suppression
and constant voltage regulation of unfiltered alternator power. To protect sensitive instruments,
the over-voltage protection system monitors the primary power bus and automatically limits peak
voltage to approximately 31.75 volts. Each field control module will cause the corresponding
alternator circuit breaker to open in cases of field output overloads, and overvoltage. In the event
an over-voltage condition occurs, the corresponding field control module automatically removes
alternator field current to shut down the corresponding alternator. Each field control module has
been integrated into the MCU case, for durability and reliability.
EFFECTIVITY:
All
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AIRPLANE MAINTENANCE MANUAL
MODEL SR20
J. Low Volts Warning Light
The airplane is equipped with a red LOW VOLTS warning light in the annunciator panel, located on the
left side of the instrument panel.
Serials 1005 thru 1581: If bus voltage drops to approximately 24.5 volts, the field control module in the
MCU will cause the LOW VOLTS warning light will illuminate red.
Serials 1582 & subs: If Essential Bus voltage drops to approximately 24.5 volts, the data acquisition
unit will cause the LOW VOLTS warning light to illuminate red.
In twin alternator configurations, resetting the ALT 1 and ALT 2 switches from off and back on again
may reset the field control module. If the warning light does not illuminate again, normal alternator
charging has resumed. If the light illuminates again, a malfunction has occurred. (Refer to 31-50)
Illumination of the LOW VOLTS warning light along with ammeter discharge indications may occur
during low RPM conditions with an electrical load on the system, such as during a low RPM taxi. Under
these conditions, the light will go out at higher RPM. The master switch will not need to be recycled
since an over-voltage condition has not occurred to de-activate the alternator system.
K. ALT 1 and ALT 2 Fail Lights
Serials 1005 thru 1267 w/ optional dual alternator system: In conjunction with the red LOW VOLTS
warning light, the MCU will illuminate the appropriate amber alternator fail light, notifying the pilot of the
system at fault. (Refer to 31-50)
Serials 1268 thru 1581 w/o single alternator SRV: Two amber colored alternator fail lights are located
in the annunciator panel. The lights provide warning of a overloaded or inoperative alternator. The ALT
1 and ALT 2 fail lights are operated by circuits in the MCU and current sensors on the ALT 1 and ALT 2
output lines. If either alternator generates less than 2 amps (approximately), the corresponding annunciator light will illuminate steady.
Serials 1582 & subs w/o single alternator SRV: Two amber colored alternator fail lights are located in
the annunciator panel. The lights provide warning of a overloaded or inoperative alternator. The ALT 1
and ALT 2 fail lights are operated by the data acquisition unit. The DAU monitors a voltage drop across
the current shunts in the MCU on the ALT 1 and ALT 2 output lines. If either alternator generates less
than 2 amps (approximately), the corresponding annunciator light will illuminate steady.
Serials 1337 thru 1581 w/ single alternator SRV: In conjunction with the red LOW VOLTS warning light,
the MCU controls the illumination of the alternator fail light, notifying the pilot of the system at fault.
Serials 1582 & subs w/ single alternator SRV: In conjunction with the red LOW VOLTS warning light,
the data acquisition unit controls the illumination of the alternator fail light, notifying the pilot of the system at fault.
L. Volt and Ampere Meter (See Figure 24-3011)
A combination Volt and Ampere meter is mounted on the right instrument panel immediately outboard
of the oil temperature and pressure gage.
Serials 1005 thru 1382: The AMP pointer sweeps a scale from -60 to +60 amps with zero at the 9
o'clock position.
Serials 1383 thru 1581: The AMP pointer sweeps a scale from -100 to +100 amps with zero at the 9
o'clock position.
Serials 1005 thru 1267: The ammeter will indicate the current generation provided by Alternator 1,
Alternator 2, and the charge or discharge status of battery 1.
The VOLT pointer sweeps a scale from 16 to 32 volts. The voltage indication is measured off the
essential bus. The voltage required to operate the internal meter lighting is supplied through the 2-amp
Instrument Lights circuit breaker on Main Bus 1.
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EFFECTIVITY:
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CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
Serials 1268 thru 1581 w/o single alternator SRV: The ammeter will indicate the current generation
provided by Alternator 1, Alternator 2, and the charge or discharge status of battery 1.
The VOLT pointer sweeps a scale from 16 to 32 volts. The voltage indication for the Volt / Ampere
Meter is measured off the annunciator circuit breaker which is on the Essential Bus. The voltage
required to operate the internal meter lighting is supplied through the 2-amp instrument lights circuit
breaker which is on Main Bus 1. Main Bus voltage (measured at the engine instrument circuit breaker)
is displayed on the clock voltmeter for reference.
Serials 1337 thru 1581 w/ single alternator SRV: The ammeter will indicate the current generation provided by Alternator 1, and the charge or discharge status of battery 1.
The VOLT pointer sweeps a scale from 16 to 32 volts. The voltage indication for the Volt / Ampere
Meter is measured off the annunciator circuit breaker which is on the Essential Bus. The voltage
required to operate the internal meter lighting is supplied through the 2-amp instrument lights circuit
breaker which is on Main Bus 1. Main Bus voltage (measured at the engine instrument circuit breaker)
is displayed on the clock voltmeter for reference.
Serials 1582 & subs: Main and Essential Bus voltages are shown as text in the electrical data field
located in the mid-right section of the MFD and are also continuously displayed in the voltage parameters field located in the upper left corner of the PFD. The MFD and PFD receive the voltage signals via
the DAU as measured directly off the Main and Essential Buses.
In the event Main Bus voltage is less than 24.5v or exceeds 32.0v the MFD will display “Check Main
Bus” in a yellow advisory box in the lower right corner of the MFD.
In the event Essential Bus voltage is less than 24.5v or exceeds 32.0v the MFD will display “Check
Essential Bus” in a red advisory box in the lower right corner of the MFD.
Alternator 1 and Alternator 2 ampere output are shown as text in the electrical data field located in the
mid-right section of the MFD. The MFD and PFD receive the amp signals via the DAU as derived from
current shunts located in the MCU.
In the event Alternator 1 or Alternator 2 ampere output is less than 2 amps for 20 seconds or more, the
MFD will display “Check ALT 1” or “Check ALT 2” respectively, in a yellow advisory box in the lower
right corner of the MFD.
28 VDC for the digital instrument operation is supplied through the 2-amp ANNUN / ENGINE INST circuit breaker on the Avionics Essential Bus.
M. Ammeter Select Switch (See Figure 24-3011)
Serials 1005 thru 1267 w/ optional dual alternator system: An ammeter select switch is located in the
pilot's primary view and is labeled distinctly. The ammeter select switch controls which output reading
the ammeter will display, Alternator 1, Alternator 2, or the state of charge or discharge battery 1 is in.
The amps indication is derived from a current transducer located in the electrical system MCU. When
the engine is operating and the master switch is turned on, the ammeter indicates the charging rate
applied to the battery. Due to the inability of the alternators to dissipate current, the alternator ammeter
indications are positive only.
Serials 1268 thru 1581 w/o single alternator SRV: An ammeter select switch is located on the right
instrument panel and is labeled distinctly. The ammeter select switch controls which output reading the
ammeter will display the voltage from, ALT 1, ALT 2 or BAT 1. The amps indication is derived from a
current transducer located in the electrical system MCU. When the engine is operating and the BAT 1
switch is turned on, the ammeter indicates the charging rate applied to battery 1. Due to the inability of
the alternators to dissipate current, the alternator ammeter indications are positive only.
Serials 1337 thru 1581 w/ single alternator SRV: An ammeter select switch is located on the right
instrument panel and is labeled distinctly. The ammeter select switch controls which output reading the
ammeter will display the voltage from, ALT 1 or BAT 1. The amps indication is derived from a current
transducer located in the electrical system MCU. When the engine is operating and the BAT 1 switch is
EFFECTIVITY:
All
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AIRPLANE MAINTENANCE MANUAL
MODEL SR20
turned on, the ammeter indicates the charging rate applied to battery 1. Due to the inability of the alternators to dissipate current, the alternator ammeter indications are positive only.
Serials 1582 & subs: Main and Essential Bus voltages are displayed on the MFD and PFD, therefore,
no ammeter select switch is necessary.
N. Turn Coordinator Batteries - Serials 1005 thru 1267 (See Figure 24-3012)
Turn coordinator batteries provide emergency power to the turn coordinator in the event of essential
power bus failure. Turn coordinator batteries consist of three date stamped 9-VDC Duracell MN1604
batteries connected in series to provide 27-VDC to the turn coordinator and the stall warning horn.
When the turn coordinator battery switch is manually selected the turn coordinator batteries will provide at least 30 minutes of power for the turn coordinator. When replacement is required, replace all
turn coordinator batteries at the same time, ensure expiration dates are the same, and expiration date
is valid through the next annual inspection date.
Turn coordinator batteries are independently controlled and wired to the turn coordinator and stall
warning horn power source allowing it to function properly when connected with battery 1 and the alternator. Failure of the battery 1 will not affect the ability of the turn coordinator batteries to provide necessary power. Because of diode protection, a failure or malfunction of the turn coordinator batteries will
not affect Battery 1 or the alternator.
O. Battery 1 (See Figure 24-3013)
Serials w/ TCM Battery: Battery 1 is a 24-volt, 12-cell, 10-ampere hour, lead-acid aviation-grade type
battery with non-spill vent caps. The battery is mounted in the engine compartment and has a top vent
with an acid-resistant tube. The tube discharges out the bottom of the engine cowling, preventing the
build up of dangerous or explosive gasses within the engine cowl.
Serials w/ Concorde Battery: Battery 1 is a 24-volt, valve regulated, lead-acid aviation-grade type battery. The battery is mounted in the engine compartment.
Serials 1268 & subs: Battery 1 is used for engine starting and can also be used as an emergency
power source in the event Battery 2 or either alternator fails. Battery 1 provides all the electrical power
for starting the aircraft. Battery 1 also supplies the electrical power to the landing light in the event
Alternator 1 fails. Battery 1 is independently controlled by the BAT 1 switch, located in the pilot’s bolster panel. The BAT 1 switch energizes a relay in the MCU which will connect BAT 1 to the Main Distribution Bus.
P. Battery 2 - Serials 1268 & subs (See Figure 24-3014)
Battery 2 is a maintenance free rechargeable sealed lead acid battery. Battery 2 consists of two 12volt, 6-cell, 7-amp-hour batteries connected in series to provide 24-VDC to the Essential Bus. There is
no need to check the specific gravity of the electrolyte or add water to these batteries during their service life.
Battery 2 is independently controlled by using the BAT 2 switch, located in the pilot’s bolster panel. The
BAT 2 switch energizes a relay located just aft of bulkhead 222 in the MCU which will connect BAT 2 to
the Essential Bus. The electrical power from BAT 2 reaches the Essential Bus through the circuit
breaker panel. Battery 2 is mounted directly behind bulkhead 222 in an acid resistant battery container.
Battery 2 is primarily used to power the Essential Bus. The Essential Bus delivers electrical power to
the annunciator lights, turn coordinator, attitude indicator, horizontal situation indicator (HSI), stall
warning system, and alternator 2.
Failure of the BAT 1 will not affect the ability of BAT 2 to provide necessary power to the Essential Bus.
Because of diode protection, a failure or malfunction of the BAT 1 will not affect BAT 2 or either alternator output.
24-30
Page 20
15 Dec 2014
EFFECTIVITY:
All
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
2. MAINTENANCE PRACTICES
A. Alternator 1 (See Figure 24-307)
(1)
Removal - Alternator 1
(a) Set BATTERY and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove safety wire from alternator mounting bolt.
(e) Loosen alternator bolts and slip drive belt off alternator pulley.
(f)
Identify and disconnect wires from alternator.
Note:
(2)
To aid reinstallation, note position of washers on alternator mounting bolts.
(g) Remove bolts securing alternator to engine.
Installation - Alternator 1
Note:
(a)
Three shims must be used to align alternator. One shim must be positioned on
each end of the alternator mounting boss. The remaining shim must be placed on
either side of the mounting boss (as required) to obtain proper sheave alignment.
Place alternator into bracket and loosely secure upper mounting bolt, washer, shims,
washer, and nut. Alternator must be mounted using two shims on either side of alternator
mounting boss and one on the opposite end of the mounting boss.
CAUTION:
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
(m)
EFFECTIVITY:
All
Cable shielding could be installed to the Power and/or Field wire harness. If
installed, attach cable shielding wire(s) to ground terminal on alternator. Do
not install cable shielding wire(s) to AUX power terminal.
Connect wires to alternator.
Loosely secure lower alternator mounting boss to bracket using bolt, small washer, and
large washer.
Secure alternator mounting bolts.
Place a long, thin, and ridged steel ruler into the bottom of the alternator pulley and drive
pulley.
Verify pulleys are aligned. Pulleys are aligned if the ruler lays directly on the centerline of
both pulleys.
If the pulleys are not in alignment, loosen mounting bolts. Note position that shims are currently placed. Remove upper mounting bolt, nut, washer, and shims.
1
Take the shim(s) from the forward side of the alternator mounting boss and place
them on the aft side of the alternator mounting boss.
2
Loosely secure upper mounting bolt, washer, shims, washer, and nut. Verify pulleys
are aligned. Repeat procedure until pulleys are aligned.
Install drive belt onto alternator pulley and tension belt properly. Using a torque wrench,
rotate alternator pulley clockwise with 11 - 13 ft-lb (15 - 18 Nm) of force. When the belt
slips in alternator pulley within the aforementioned torque range, the belt is properly tensioned.
Tighten upper alternator mounting bolt to 400 - 450 in-lb (45 - 51 Nm).
Tighten lower alternator mounting bolts to 200 - 275 in-lb (23 - 31 Nm).
Safety wire lower alternator mounting bolt. (Refer to 20-50)
Connect battery 1.(Refer to 24-30)
Install engine cowling. (Refer to 71-10)
24-30
Page 21
01 May 2012
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
B. Alternator 1 Drive Belt (See Figure 24-307)
Alternator 1 is driven by a drive belt. The drive belt connects alternator 1 to the alternator drive sheave,
which is powered by the engine’s crankshaft. If the drive belt becomes insufficiently tensioned or
breaks, output of alternator 1 will be reduced. The drive belt should be inspected periodically for proper
tension and wear. Replace all worn drive belts.
(1)
(2)
24-30
Page 22
19 Sep 2010
Removal - Alternator Drive Belt
(a) Set BATTERY and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove safety wire from alternator mounting bolt.
(e) Loosen alternator bolts and slip drive belt off alternator pulley.
(f)
Remove propeller. (Refer to 61-10)
(g) Remove drive belt.
Installation - Alternator Drive Belt
(a) Install alternator drive belt around drive pulley.
(b) Install propeller. (Refer to 61-10)
(c)
Install drive belt onto alternator pulley and tension belt properly. Using a torque wrench,
rotate alternator pulley clockwise with 11 - 13 ft-lb (15 - 18 Nm) of force. When the belt
slips in alternator pulley within the specified torque range, the belt is properly tensioned.
(d) Tighten upper alternator mounting bolt to 400 - 450 in-lb (45 - 51 Nm).
(e) Tighten lower alternator mounting bolt to 200 - 275 in-lb (23 - 31 Nm).
(f)
Safety wire lower alternator mounting bolt. (Refer to 20-50)
(g) Connect battery 1. (Refer to 24-30)
(h) Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
All
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
C. Alternator 1 Drive Sheave (See Figure 24-307)
(1)
(2)
Removal - Alternator Drive Sheave
(a) Remove alternator drive belt. (Refer to 24-30)
(b) Remove bolts and washers securing alternator drive sheave and backing plates to prop
flange.
(c)
Remove alternator drive sheave and backing plates.
Installation - Alternator Drive Sheave
Note:
(a)
(b)
EFFECTIVITY:
All
Exercise caution when securing the backing plates to the prop flange. The alignment holes in the backing plates must be aligned before securing the mounting
hardware.
Install bolts and washers securing alternator drive sheave and backing plates to prop
flange.
Install alternator drive belt. (Refer to 24-30)
24-30
Page 23
19 Sep 2010
CIRRUS
AIRPLANE MAINTENANCE MANUAL
5
BRACKET
(REF)
3
MODEL SR20
5
3
7
4
6
4
3
4
3
9
5
1
8
3
3
2
CABLE
(REF)
3
5
5
3
CABLE
(REF)
LEGEND
1. Alternator
2. Bolt
3. Washer
4. Shim
5. Nut
6. Drive Sheave
7. Backing Plate
8. Pulley
9. Mounting Boss
NOTE
Tighten to 400-450 inch pounds (45-51 Nm).
Tighten to 200-275 inch pounds (23-31 Nm)
and safety wire.
Place one shim on each side of alternator
mounting boss. Remaining shim must be
used on either side of mounting boss to
obtain proper sheave alignment.
SR20_MM24_1147D
Figure 24-307
Alternator 1
24-30
Page 24
19 Sep 2010
EFFECTIVITY:
All
2
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
D. Alternator 2 (See Figure 24-308)
(1)
(2)
Removal - Alternator 2
(a) Set BATTERY and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Identify and disconnect wires from alternator terminals.
(e) Remove nuts and washers securing alternator to engine. Remove alternator from airplane.
(f)
Discard old gasket and remove residual gasket material from alternator and engine.
Disassembly - Alternator 2
Note:
(3)
To facilitate removal of shear coupling assembly from coupling pins on alternator, tightly grip and rock spline of shear coupling assembly back and forth
until loosened.
(a) Pull shear coupling assembly from alternator.
Assembly - Alternator 2
(a)
Acquire necessary tools, equipment, and supplies.
Description
Mallet
P/N or Spec.
-
Supplier
Any Source
Purpose
Tap shear coupling onto shaft
coupling pins.
(b)
(4)
Position and align shear coupling assembly to alternator pins. Gently tap shear coupling
assembly with mallet until coupling is seated onto pins.
Installation - Alternator 2
(a) Place alternator and new gasket into position. Hand tighten washers and nuts in an alternating pattern securing alternator to engine.
(b) Serials 1005 thru 1267, 2016 & subs w/ Perspective Avionics: Torque nuts to 200 in-lb
(22.6 Nm) in an alternating pattern.
(c)
Serials 1268 thru 2015, 2016 & subs w/o Perspective Avionics: Torque nuts to 50 - 70 in-lb
(5.6 - 7.9 Nm) in an alternating pattern.
CAUTION:
(5)
Cable shielding could be installed to the Power and/or Field wire harness. If
installed, attach cable shielding wire(s) to ground terminal on alternator. Do
not install cable shielding wire(s) to AUX power terminal.
(d) Connect alternator wires to appropriate terminals.
(e) Connect battery 1. (Refer to 24-30)
(f)
Install engine cowling. (Refer to 71-10)
Inspection/Check - Alternator 2
(a) Set BAT 1, BAT 2 and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Visually inspect rear housing cooling slots for gray dust residue which may indicate bearing failure.
(e) Verify alternator is securely mounted to engine and no oil leakage is visible around alternator base.
(f)
Visually inspect alternator wiring and electrical connectors for security and condition.
EFFECTIVITY:
All
24-30
Page 25
01 May 2012
CIRRUS
(g)
(h)
(i)
(j)
(k)
24-30
Page 26
01 May 2012
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
Visually inspect output terminal and nut for dark discoloration. If discolored or corroded,
replace terminal ring on output wire.
1
Remove nut and washer securing output wire to alternator terminal.
2
Clean output terminal and nut with brass wire brush.
3
Cut old end of wire off and strip new end to obtain a clean and bright conductor.
4
Insert end of wire into terminal ring and crimp.
5
Position terminal ring on output terminal and secure with washer and nut.
Clean casting webs between mounting flanges and alternator housing and visually inspect
casting webs for cracks. If a crack exists in any of the four casting webs, replace alternator.
If it is difficult to distinguish casting features from cracks, refer to Advisory Circular 43.131B Acceptable Methods, Techniques, and Practices - Aircraft Inspection And Repair for
additional non-destructive testing.
Connect battery 1. (Refer to 24-30)
Perform the Before Takeoff checklist as described in the Normal Procedures section of the
Pilot’s Operating Handbook.
1
Verify both ALT 1 and ALT 2 caution lights are out.
2
Verify positive amps indication for each alternator.
3
Listen for excessive noise or vibration which may indicate bearing failure.
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
All
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
4
1
CABLE
(REF)
2
3
2
2
3
3
CABLE
(REF)
NOTE
Torque nuts to 200 in-lb (22.6 Nm).
Serials 1005 thru 1267,
2016 & subs w/ Perspective Avionics.
LEGEND
1. Alternator
2. Washer
3. Nut
4. Gasket
SR20_MM24_1315D
Figure 24-308
Alternator 2 - Serials 1005 thru 1267, 2016 & subs w/ Perspective Avionics (Sheet 1 of 2)
EFFECTIVITY:
Serials 1005 thru 1267, 2016 & subs w/ Perspective
Avionics
24-30
Page 27
19 Sep 2010
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
2
4
2
3
10
1
2
3
6
9
5
LEGEND
1. Alternator
2. Washer
3. Nut
4. Gasket
5. Mounting Flange
6. Casting Web
7. Alternator Housing
8. Output Terminal
9. Rear Housing Cooling Slots
10. Shear Coupling Assembly
7
8
NOTE
Torque nuts to 50 - 70 in-lb (5.6 - 7.9 Nm).
Serials 1268 thru 2015,
2016 & subs w/o Perspective Avionics.
SR20_MM24_1580D
Figure 24-308
Alternator 2 - Serials 1268 thru 2015, 2016 & subs w/o Perspective Avionics (Sheet 2 of 2)
24-30
Page 28
19 Sep 2010
EFFECTIVITY:
Serials 1268 thru 2015, 2016 & subs w/o Perspective
Avionics
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
E. Master Control Unit - Serials 1005 thru 1267 (See Figure 24-309)
This MCU is not field repairable and must be replaced if faulty.
(1)
Removal - Master Control Unit
(a) Set BATTERY and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery. (Refer to 24-30)
Note:
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
To facilitate re-installation, label all wires prior to removal.
Identify wires routed to alternator 1 and disconnect at alternator. Remove cable ties securing wires together.
Serials 1005 thru 1267 w/ dual alternator: Identify wires routed to alternator 2 and disconnect at alternator.
Identify wire routed to starter and disconnect at starter.
Identify wire routed to backup vacuum pump and disconnect at MCU.
Identify wire routed to ground bus bar assembly and disconnect at MCU.
Identify wires routed to external power receptacle and disconnect at MCU.
At MCU, identify P108 and P109 connectors and disconnect from J108 and J109 connectors.
Serials 1005 thru 1267 w/ dual alternator: Identify P111 connector and disconnect from
J111 connector on MCU.
Loosen adel clamps securing MCU wires to firewall, battery bracket, engine mount, and
engine baffling.
CAUTION:
(2)
Remove MCU wires from engine compartment carefully to avoid damaging
other components.
(m) Remove bolts and washers securing MCU to firewall and remove MCU from airplane.
Installation - Master Control Unit
(a)
Acquire necessary tools, equipment, and supplies.
Description
High Temperature Silicone Sealant
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
P/N or Spec.
RTV 736
Supplier
Dow Corning
Purpose
Sealant.
Position MCU to firewall and secure with bolts and washers.
Route wires to alternator 1 and connect at alternator. Secure wires together with cable
ties.
Serials 1005 thru 1267 w/ dual alternator: Route wires to alternator 2 and connect at alternator.
Route wire to starter and connect at starter.
Route wire from backup vacuum pump and connect at MCU.
Route wire from ground bus bar assembly and connect at MCU.
Route wires from external power receptacle and connect at MCU.
At MCU, connect P108 and P109 connectors to J108 and J109 connectors.
Serials 1005 thru 1267 w/ dual alternator: At MCU, connect P111 connector to J111 connector.
Verify wire routing and tighten adel clamps securing MCU wires to firewall, battery bracket,
engine mount, and engine baffling.
EFFECTIVITY:
Serials 1005 thru 1267
24-30
Page 29
19 Sep 2010
CIRRUS
(l)
(m)
(n)
24-30
Page 30
19 Sep 2010
AIRPLANE MAINTENANCE MANUAL
Apply firewall sealant to bolts securing MCU and adel clamps to firewall.
Connect battery. (Refer to 24-30)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials 1005 thru 1267
MODEL SR20
CIRRUS
F.
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
Master Control Unit - Serials 1268 & subs (See Figure 24-309)
MCU part number 14600-002, 16600-001, 19900-001, & 19800-001 are field repairable to the extent
provided for in Chapter 24-00, Electrical Power Troubleshooting. (Refer to 24-00) Field repair is limited
to replacing the following components: current sensors, logic module, fuses, and field control modules.
The MCU part number may be determined from a placard located on the MCU chassis.
Note:
Airplane serial effectivities may vary from shown if originally installed MCU has been
replaced.
MCU part number 14600-002 (MCU 100) is installed on SR20 airplanes serial numbers 1268 thru
1524.
MCU part number 16600-001 (MCU 120) is installed on SR20 airplanes serial numbers 1525 thru
1581.
MCU part number 19900-001 (MCU 130) is installed on SR20 airplanes serial numbers 1582 and subsequent.
MCU part number 19800-001 (MCU 140) is installed on SR20 airplanes serial numbers 2016 & subs
w/ Perspective Avionics.
(1)
Removal - Master Control Unit
(a) Set BATTERY and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove nuts and washers securing grounding strap to MCU chassis.
(e) MCU 14600-002, & 16600-001: Identify and disconnect P108, P109, P111, and P115 connectors from J108, J109, J111, and J115 connectors.
(f)
MCU 16600-001: Disconnect P757 connector from J757 connector, if installed.
(g) MCU 19900-001: Identify and disconnect P135, P136, P137, and P138 connectors from
J135, J136, J137, and J138 connectors.
(h) MCU 19800-001: Disconnect P180, P181, P182, and P183 connectors.
(i)
MCU 19900-001: Remove nuts, washers, and clamps securing wire harness loom to
chassis.
(j)
MCU 14600-002 & 16600-001: Remove MCU cover. (Refer to 24-30)
Note:
(2)
MCU 14600-002: Label cable guide routing holes with cable component
name to facilitate re-installation.
(k)
MCU 14600-002: Remove screws and washers securing cable guide to MCU chassis.
(l)
Remove nuts and washers securing alternator 1 cable assembly to bus bar stud.
(m) Remove nuts and washers securing alternator 2 cable assembly to bus bar stud.
(n) Remove nuts and washers securing battery 1 cable assembly to bus bar stud.
(o) Remove nuts and washers securing starter cable assembly to bus bar stud.
(p) Remove bolts and washers securing MCU to firewall. Remove MCU from airplane.
Installation - Master Control Unit
(a)
Acquire necessary tools, equipment, and supplies.
Description
High Temperature Silicone Sealant
EFFECTIVITY:
Serials 1268 & subs
P/N or Spec.
RTV 736
Supplier
Dow Corning
Purpose
Sealant.
24-30
Page 31
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
(b)
(3)
Position MCU to firewall and secure with bolts and washers. Apply sealant over bolt
heads.
(c)
Install washers and nuts securing alternator 1 cable assembly to bus bar stud.
(d) Install washers and nuts securing alternator 2 cable assembly to bus bar stud.
(e) Install washers and nuts securing battery 1 cable assembly to bus bar stud.
(f)
Install washers and nuts securing starter cable assembly to bus bar stud.
(g) MCU 14600-002: Install screws and washers securing cable guide to MCU chassis.
(h) MCU 14600-002, & 16600-001: Connect P108, P109, P111, and P115 connectors to J108,
J109, J111, and J115 connectors.
(i)
MCU 16600-001: Connect P757 connector to J757 connector, if installed.
(j)
MCU 19900-001: Connect P135, P136, P137, and P138 connectors to J135, J136, J137,
and J138 connectors.
(k)
MCU 19800-001: Connect P180, P181, P182, and P183 connectors.
(l)
MCU 19900-001: Position wire harness loom to chassis and secure with clamps, washers,
and nuts.
(m) Install washers and nuts securing grounding strap to MCU chassis.
(n) MCU 14600-002: Install MCU cover. (Refer to 24-30)
(o) MCU 14600-002 & 16600-001: Apply sealant around cable guide holes where cable
assemblies and connector wires exit MCU.
(p) Connect battery 1. (Refer to 24-30)
(q) Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
(r)
Install engine cowling. (Refer to 71-10)
Operational Inspection - Master Control Unit - Serials w/o Perspective Avionics
WARNING:
(a)
(b)
(c)
(d)
(e)
24-30
Page 32
01 Jan 2016
In order to perform the following check the engine must be operating. Do
not stand or let anyone else stand close to the arc of the airplane’s propeller
while conducting this check.
Verify all circuit breakers are set.
Toggle battery 2 master switch to the ON position and verify the following occurs:
1
Volt / Amp meter indicates at least 24 volts on battery 2.
2
Serials 1268 thru 1581: ALT 1 and ALT 2 caution lights illuminate.
3
Serials 1582 & subs: ALT 2 caution light illuminates.
4
Flap position light off.
5
Attitude gyro low voltage flag hidden.
6
Serials 1268 thru 1336, 1337 thru 1422 w/o PFD: HSI HDG flag hidden within five
minutes.
7
Serials 1337 thru 1422 w/ PFD, 1423 & subs: PFD powers up.
8
Serials 1268 thru 1336, 1337 thru 1422 w/o PFD: Turn Coordinator low voltage flag
hidden.
9
Autopilot ready indication after gyro spool up.
Toggle battery 1 master switch to the ON position and verify the following occurs:
1
ALT 1 and ALT 2 fail lights are on.
2
Flap position light illuminates.
3
Engine instruments are operational and manifold pressure gage indicates approximately the altimeter setting.
4
Ammeter select switch shows slight discharge in BAT position.
Start Engine and set engine speed at 1000 RPM.
Verify landing light, pitot heat, avionics, strobe lights, and navigation lights are on.
EFFECTIVITY:
Serials 1268 & subs
CIRRUS
(f)
(g)
(h)
(i)
(j)
(k)
AIRPLANE MAINTENANCE MANUAL
Switch ALT 1 ON and ALT 2 ON.
Increase RPM to 1700.
Check that LOW VOLT light is off and ammeter shows no current discharge in BAT position.
Increase RPM to 2200.
Check that LOW VOLT light is off and ammeter shows no current discharge in BAT position.
Switch ALT 1 ON and ALT 2 OFF. Verify and record operating values.
Voltage Indication
(l)
Ammeter Indication
Voltmeter
ALT 1
BAT
ALT 2
LOW
VOLTS
ALT 1
Steady
ALT 2
Steady
27V - 28.3V
27V - 28V
Pos < 40A
0 - Pos
0A
OFF
OFF
ON
Switch ALT 1 OFF and ALT 2 ON. Verify and record operating values.
Ammeter Indication
Voltmeter
ALT 1
BAT
ALT 2
LOW
VOLTS
ALT 1
Steady
ALT 2
Stead
y
20V - 24V
28V - 29V
0A
0A - Neg
2A - 20A
OFF
ON
OFF
Switch ALT 1 ON and ALT 2 ON. Verify and record operating values.
Ammeter Indication
Annunciator Illumination
Clock/Volts
Voltmeter
ALT 1
BAT
ALT 2
LOW
VOLTS
ALT 1
Steady
ALT 2
Steady
27V 28.3V
28V 29V
Pos <
40A
0A Pos
2A 20A
OFF
OFF
OFF
Switch ALT 1 OFF and ALT 2 OFF. Verify and record operating values.
Voltage Indication
(o)
Annunciator Illumination
Clock/Volts
Voltage Indication
(n)
Annunciator Illumination
Clock/Volts
Voltage Indication
(m)
MODEL SR20
Ammeter Indication
Annunciator Illumination
Clock/Volts
Voltmeter
ALT 1
BAT
ALT 2
LOW
VOLTS
ALT 1
Steady
ALT 2
Steady
20V - 24V
20V 24V
0A
Neg < 40A
0A
ON
ON
ON
Shut down engine.
EFFECTIVITY:
Serials 1268 & subs
24-30
Page 33
01 Jan 2016
CIRRUS
(4)
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
Operational Inspection - Master Control Unit - Serials w/ Perspective Avionics
In order to perform the following check the engine must be operating. Do not stand or let anyone
else stand close to the arc of the airplane’s propeller while conducting this check.
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
Verify all circuit breakers are set.
Toggle battery 2 master switch to the ON position and verify the following occurs:
1
Flap position light off.
2
Serials w/o MD302 Standby Attitude Module: Standby attitude gyro low voltage flag
hidden.
3
Serials w/ MD302 Standby Attitude Module: MD302 Standby Attitude Module powers up.
4
PFD powers up.
5
MFD is off.
6
Essential Bus voltage (indicated on PFD) is 22 to 26 volts.
7
ALT 1 and ALT 2 caution annunciations on PFD.
Toggle battery 1 master switch to the ON position and verify the following occurs:
1
Flap position light illuminates.
2
MFD powers up.
3
Pull PFD #1 circuit breaker and verify PFD remains on.
4
Reset PFD #1 circuit breaker.
5
Serials w/o MD302 Standby Attitude Module: Pull STDBY ATTD #1 circuit breaker
and verify standby attitude gyro voltage flag remains hidden.
6
Serials w/ MD302 Standby Attitude Module: Pull STDBY ATTD #1 circuit breaker
and verify MD302 Standby Attitude Module remains powered up.
7
Reset STDBY ATTD #1 circuit breaker.
8
Pull MFD #2 circuit breaker and verify MFD remains on.
9
Reset MFD #2 circuit breaker.
10
Switch on Landing Light and verify Landing Light illuminates.
11
Switch off Landing Light.
12
Serials w/ Fan or Air Conditioning: Turn on Cabin Fan and verify fan is on.
13
Serials w/ Fan or Air Conditioning: Turn off Cabin Fan.
14
ALT 1 and ALT 2 caution annunciations on PFD.
15
BAT 1 current indicator shows slight discharge.
Start Engine and set engine speed at 1000 RPM.
Switch ALT 1 ON and ALT 2 ON.
Verify landing light, pitot heat, avionics, strobe lights, and navigation lights are on.
Increase RPM to 1700.
Check that BAT 1, ALT 1, ALT 2, ESS BUS, M BUS 1, and M BUS 2 caution and warning
annunciations are off.
Increase RPM to 2200.
Check that BAT 1, ALT 1, ALT 2, ESS BUS, M BUS 1, and M BUS 2 caution and warning
annunciations are off.
Serials 2016 thru 2064 w/ Vent only: Turn vent airflow off and on. Verify control of airflow
into the cabin.
Switch ALT 1 ON and ALT 2 OFF. Verify and record operating values from MFD.
Bus Volts (V)
ESS
24-30
Page 34
01 Jan 2016
M1
Current (A)
M2
ALT 1
EFFECTIVITY:
Serials 1268 & subs
ALT 2
BAT 1
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
Bus Volts (V)
= M1 - 0.7
(± 0.2)
(m)
27.0V 28.3V
Current (A)
= M1 - 0.7
(± 0.2)
2A - 72A
Current (A)
ESS
M1
M2
ALT 1
ALT 2
BAT 1
= M2 - 0.7
(± 0.2)
22V - 26V
28.1V 29.1V
0A
2A - 50A
Neg - 0
Switch ALT 1 ON and ALT 2 ON. Verify and record operating values from MFD.
Bus Volts (V)
(o)
Current (A)
ESS
M1
M2
ALT 1
ALT 2
BAT 1
= M2 - 0.7
(± 0.2)
27.0V 28.3V
28.1V 29.1V
Pos < 72A
2A - 50A
0 - Pos
Switch ALT 1 OFF and ALT 2 OFF. Verify and record operating values from MFD.
Bus Volts (V)
(5)
0 - Pos
Switch ALT 1 OFF and ALT 2 ON. Verify and record operating values from MFD.
Bus Volts (V)
(n)
0A
Current (A)
ESS
M1
M2
ALT 1
ALT 2
BAT 1
22V - 26V
22V - 26V
= M1 - 0.7
(± 0.2)
0A
0A
Neg - 0
(p) Shut down engine.
Inspection/Check - Master Control Unit
(a)
Acquire necessary tools, equipment, and supplies.
Description
High Temperature Silicone Sealant
RTV 736
Supplier
Purpose
Dow Corning
Sealant.
-
Any Source
General Cleaning.
Isopropyl Alcohol
99% or
higher purity
Any Source
Solvent clean.
Corrosion Inhibitor
(aerosol)
MIL-C-81309
Type III
Any Source
Prevent corrosion.
Cotton Cloth
(clean and lint free)
(b)
(c)
P/N or Spec.
Set BATTERY and AVIONICS switches to OFF positions.
Remove engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials 1268 & subs
24-30
Page 35
01 Jan 2016
CIRRUS
(d)
(e)
(f)
AIRPLANE MAINTENANCE MANUAL
Disconnect battery 1. (Refer to 24-30)
Remove MCU cover. (Refer to 24-30)
Visually inspect inside MCU for evidence of water. If water if found, dry MCU and components with a clean cotton cloth.
Note:
(g)
(h)
(i)
(j)
(k)
(l)
(m)
(n)
24-30
Page 36
01 Jan 2016
MODEL SR20
Evidence of surface corrosion does not require replacement of MCU components. If corrosion is found, verify MCU operation by performing Operational Inspection - Master Control Unit.
Apply corrosion inhibitor as follows:
1
Cover surrounding components and structures to prevent inadvertent application of
corrosion inhibitor to these areas.
2
Apply a thin coat of corrosion inhibitor to MCU circuit board, internal components,
and connectors per the manufacturer’s instructions.
Verify security of MCU chassis to firewall.
Visually inspect cable assemblies and connector wires for chafing and security.
Serials w/ MCU 100 or MCU120: Visually inspect sealant for a tight seal around cable
guide holes where cable assemblies and connector wires exit MCU.
Serials w/ MCU 100 or MCU120: If necessary, reapply sealant to MCU as follows:
1
Solvent clean areas of MCU to be sealed. (Refer to 20-30)
2
Apply sealant around cable guide holes where cable assemblies and connector
wires exit MCU.
Install MCU cover. (Refer to 24-30)
Connect battery 1. (Refer to 24-30)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials 1268 & subs
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
OPTIONAL ALTERNATOR 2
(REF)
FIREWALL
(REF)
4
3
1
2
3
GROUND BUS
BAR ASSEMBLY
(REF)
4
STARTER
(REF)
2
3
ALTERNATOR 1
(REF)
VACUUM PUMP
(REF)
OIL FILTER
(REF)
EXTERNAL POWER
RECEPTACLE
(REF)
LEGEND
1. Master Control Unit (MCU)
2. Bolt
3. Washer
4. Adel Clamp
Serials 1005 thru 1267.
SR20_MM24_1601F
Figure 24-309
MCU Installation - Serials 1005 thru 1267 (Sheet 1 of 5)
EFFECTIVITY:
Serials 1005 thru 1267
24-30
Page 37
01 Jan 2012
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
2
ER
1
Y
RT
1
OR
R
A
T
A
TE
OR
ST
N
T
T
R
TO
BA
NA
TE
ER
AL
TO
T
TO
AL
TO
WIRE LOOM
(REF)
P109 (REF)
P111 (REF)
P115 (REF)
P108 (REF)
3
5
16
6
3 15 17
7
5
6
3
7
FIREWALL
(REF)
EXTERNAL POWER
RECEPTACLE
(REF)
18
1
3
2
5
12
13
6
3
11
8
14
TO GROUND
BUS BAR
ASSEMBLY
9
10
13
6
3
NOTE
Apply sealant to top corners of MCU, cable exits,
and around external power receptacle.
LEGEND
1. Master Control Unit (MCU)
2. Bolt
3. Washer
5. Screw
6. Lock Washer
7. Cable Guide
8. Starter Cable
9. Battery 1 Cable
10. Alternator 1 Cable
11. Alternator 2 Cable
12. Ground Cable
13. Nut
14. MCU Cover
15. J115 Connector
16. J109 Connector
17. J108 Connector
18. J111 Connector
Serials 1268 thru 1524.
Figure 24-309
Master Control Unit Installation - Serials 1268 thru 1524 (Sheet 2 of 5)
24-30
Page 38
01 Jan 2012
EFFECTIVITY:
Serials 1268 thru 1524
SR20_MM24_1741F
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
WIRE LOOM
(REF)
NOTE
Apply sealant to top corners of MCU
and around external power receptacle.
P109 (REF)
P111 (REF)
P757 (REF)
P115 (REF)
P108 (REF)
2
TER
OR
TAR
S
NAT
R
TO
E
1
ALT
ERY
1
TO
ATT
B
TOR
TO
RNA
E
T
AL
TO
15
16
17
18
19
FIREWALL
(REF)
EXTERNAL POWER
RECEPTACLE
(REF)
3
1
3
2
12
13
6
3
11
8
TO GROUND
BUS BAR
ASSEMBLY
10
9
LEGEND
1. Master Control Unit (MCU)
2. Bolt
3. Washer
5. Screw
6. Lock Washer
8. Starter Cable
9. Battery 1 Cable
10. Alternator 1 Cable
11. Alternator 2 Cable
13
6
14
3
12. Ground Cable
13. Nut
15. J115 Connector
16. J109 Connector
17. J108 Connector
18. J111 Connector
19. J757 Connector
5
Serials 1525 thru 1581.
SR20_MM24_2096A
Figure 24-309
Master Control Unit Installation - Serials 1525 thru 1581 (Sheet 3 of 5)
EFFECTIVITY:
Serials 1525 thru 1581
24-30
Page 39
01 Jan 2012
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
22
EXTERNAL POWER
RECEPTACLE
(REF)
1
TO ALTERNATOR 1
21
3
TO STARTER
TO BATTERY
13
TO ALTERNATOR 2
12
6
3
3
2
20
3
11
13
9
TO GROUND
BUS BAR
ASSEMBLY
8
P138
(REF)
P136
(REF)
13
3
6
10
22
21
P137
(REF)
P135
(REF)
FIREWALL
(REF)
NOTE
Apply sealant to top corners of MCU
and around external power receptacle.
LEGEND
1. Master Control Unit (MCU)
2. Bolt
3. Washer
6. Lock Washer
8. Starter Cable
9. Battery 1 Cable
10. Alternator 1 Cable
11. Alternator 2 Cable
12. Ground Cable
13. Nut
20. Adel Clamp
21. Wire Loom
22. Cable Tie
SR20_MM24_2191A
Figure 24-309
Master Control Unit Installation - Serials 1582 & subs w/o Perspective Avionics (Sheet 4 of 5)
24-30
Page 40
01 Jan 2012
EFFECTIVITY:
Serials 1582 & subs w/o Perspective Avionics
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
FIREWALL
(REF)
3
1
3
2
11
12
5
3
10
8
P182
(REF)
P180
(REF)
9
7
12
5
3
21
20
P183
(REF)
DETAIL D
P181
(REF)
LEGEND
1. Master Control Unit (MCU)
2. Bolt
3. Washer
5. Lock Washer
7. Starter Cable
8. Battery 1 Cable
9. Alternator 1 Cable
10. Alternator 2 Cable
11. Ground Cable
12. Nut
20. Wire Loom
21. Cable Tie
SR20_MM24_2904A
Figure 24-309
Master Control Unit Installation - Serials 2016 & subs w/ Perspective Avionics (Sheet 5 of 5)
EFFECTIVITY:
Serials 2016 & subs w/ Perspective Avionics
24-30
Page 41
01 Jan 2012
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
G. MCU Cover - Serials w/ MCU 14600-001, 14600-002, 16600-001, and 19900-001 (See Figure 243010)
(1)
(2)
Removal - MCU Cover
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Using a plastic scraper, remove sealant from corners of MCU and from around external
power receptacle.
(e) Remove screws securing MCU cover to chassis. Remove MCU cover.
Installation - MCU Cover
(a)
Acquire necessary tools, equipment, and supplies.
Description
P/N or Spec.
Corrosion Inhibitor
(aerosol)
MIL-C-81309
Type III
Any Source
Prevent corrosion.
High Temperature Silicone Sealant
RTV 736
Dow Corning
Sealant.
-
Any Source
General Cleaning.
99% or
higher purity
Any Source
Solvent clean.
Cotton Cloth
(clean and lint free)
Isopropyl Alcohol
(b)
(c)
(d)
(e)
(f)
(g)
24-30
Page 42
01 Jan 2016
Supplier
Purpose
Apply corrosion inhibitor as follows:
1
Cover surrounding components and structures to prevent inadvertent application of
corrosion inhibitor to these areas.
2
Apply a thin coat of corrosion inhibitor to MCU circuit board, internal components,
and connectors per the manufacturer’s instructions.
Position MCU cover to chassis and secure with screws.
Solvent clean upper corners of MCU chassis, and along edge of external power receptacle. (Refer to 20-30)
Apply sealant to openings at upper corners of MCU chassis, and along edge of external
power receptacle.
Connect battery 1. (Refer to 24-30)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials w/ MCU 14600-001, 14600-002, 16600-001,
and 19900-001
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
H. MCU Cover - Serials w/ MCU 19800-001 (See Figure 24-3010)
(1)
(2)
Removal - MCU Cover
(a) Set BAT 1, BAT 2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove screws securing MCU cover to chassis. Remove MCU cover.
Installation - MCU Cover
(a)
(b)
(c)
(d)
(e)
Acquire necessary tools, equipment, and supplies.
Description
P/N or Spec.
Corrosion Inhibitor
(aerosol)
MIL-C-81309
Type III
Supplier
Any Source
Purpose
Prevent corrosion.
Apply corrosion inhibitor as follows:
1
Cover surrounding components and structures to prevent inadvertent application of
corrosion inhibitor to these areas.
2
Apply a thin coat of corrosion inhibitor to MCU circuit board, internal components,
and connectors per the manufacturer’s instructions.
Position MCU cover to chassis and secure with screws.
Connect battery 1. (Refer to 24-30)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials w/ MCU 19800-001
24-30
Page 43
01 Jan 2016
CIRRUS
I.
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
MCU Bottom Cover - Serials w/ MCU 16600-001 & 19900-001 (See Figure 24-3010)
(1)
Removal - Serials w/ MCU Bottom Cover
(a) Remove MCU cover.
(b) MCU 16600-001: Remove nuts, washers, and clamps securing wire harness loom to
chassis.
Note:
MCU 16600-001: Label cable guide routing holes with wire harness name
to facilitate re-installation.
(c)
(d)
(2)
24-30
Page 44
01 Jan 2016
MCU 16600-001: Remove screws and washers securing cable guide to chassis.
MCU 19900-001: Identify and disconnect P135, P136, P137, and P138 connectors from
J135, J136, J137, and J138 connectors.
(e) MCU 19900-001: Remove screws securing cable plate to bottom cover.
(f)
Remove screws securing MCU bottom cover to chassis.
(g) Remove MCU bottom cover from chassis.
Installation - Serials w/ MCU Bottom Cover
(a) Position bottom cover to chassis and secure with screws.
(b) MCU 16600-001: Position cable guide around wire harness J108, J109, J111, J115, and
J757, if installed.
(c)
MCU 16600-001: Install screws and washers securing cable guide to chassis.
(d) MCU 16600-001: Position wire harness loom to chassis and secure with clamps, washers,
and nuts.
(e) MCU 19900-001: Position cable plate to bottom cover and secure with screws.
(f)
Install MCU cover.
(g) MCU 19900-001: Connect P135, P136, P137, and P138 connectors to J135, J136, J137,
and J138 connectors.
EFFECTIVITY:
Serials w/ MCU 16600-001 & 19900-001
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
J. ALT 1 Current Sensor - Serials w/ MCU 14600-002 & 16600-001 (See Figure 24-3010)
The ALT 1 current sensor, integral to the MCU, is located on the LH side of the power board assembly.
(1)
Removal - ALT 1 Current Sensor
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) Disconnect ALT 1 cable assembly from ALT 1 bus bar stud.
(f)
MCU 14600-002: Loosen nuts securing ALT 1 bus bar to terminal ring support bracket.
(g) MCU 16600-001: Loosen nuts securing ALT 1 bus bar to the MCU chassis.
Note:
Inboard fuse stud securing ALT 1 current sensor to power board assembly
is not soldered to board and may fall lose if not held in place.
(h)
(i)
(j)
(k)
(l)
(2)
MCU 14600-002: Remove kep-nuts securing 80A fuse to power board assembly.
MCU 16600-001: Remove kep-nuts securing 100A fuse to power board assembly.
Remove screws and washers securing ALT 1 current sensor to power board assembly.
Remove ALT 1 current sensor from power board assembly.
Disassemble ALT 1 bus bar stud, washers, bus bar IXa, and nuts from ALT 1 current sensor stand-off.
Installation - ALT 1 Current Sensor
(a)
Acquire necessary tools, equipment, and supplies.
Description
Loctite®
(b)
P/N or Spec.
222
Supplier
Any Source
Purpose
Fuse installation.
Assemble ALT 1 bus bar stud, washers, bus bar IXa, and nuts to ALT 1 current sensor
stand-off.
CAUTION:
Before installing, examine current sensor module for bent pins. If bent pins
are found, gently straighten them.
Do not force current sensor assembly into power board jack. Current sensor
should install into jack with gentle pressure.
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
MCU 14600-002: Align ALT 1 current sensor module pins to power board jack while simultaneously aligning bus bar IXa on fuse stud and ALT 1 bus bar stud over terminal ring support bracket.
MCU 16600-001: Align Alt 1 current sensor module pins to power board jack while simultaneously aligning bus bar IXa on fuse stud and ALT 1 bus bar stud through hole in MCU
chassis.
Gently press ALT 1 current sensor assembly onto power board.
Install screws and washers securing ALT 1 current sensor to power board assembly.
Apply Loctite® to power board fuse studs.
MCU 14600-002: Position 80A fuse to power board assembly and secure with kep-nuts.
MCU 16600-001: Position 100A fuse to power board assembly and secure with kep-nuts.
MCU 14600-002: Tighten nuts securing ALT 1 bus bar to terminal ring support bracket.
MCU 16600-001: Tighten nuts securing ALT 1 bus bar to MCU chassis.
EFFECTIVITY:
Serials w/ MCU 14600-002 & 16600-001
24-30
Page 45
01 Jan 2016
CIRRUS
(l)
(m)
(n)
(o)
(p)
24-30
Page 46
01 Jan 2016
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
Connect ALT 1 cable assembly to ALT 1 bus bar stud.
Install MCU cover. (Refer to 24-30)
Connect battery 1. (Refer to 24-30)
Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials w/ MCU 14600-002 & 16600-001
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
K. ALT 2 Current Sensor - Serials w/ MCU 14600-002 & 16600-001 (See Figure 24-3010)
The ALT 2 current sensor, integral to the MCU, is located on the LH side of the power board assembly.
(1)
(2)
Removal - ALT 2 Current Sensor
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) Disconnect ALT 2 cable assembly from ALT 2 bus bar stud.
(f)
MCU 14600-002: Loosen nuts securing ALT 2 bus bar to terminal ring support bracket.
(g) MCU 16600-001: Loosen nuts securing ALT 2 bus bar to MCU chassis.
(h) Remove kep-nuts securing 40A fuse to power board assembly.
(i)
Remove screws and washers securing ALT 2 current sensor to power board assembly.
(j)
Remove ALT 2 current sensor from power board assembly.
(k)
Disassemble ALT 2 bus bar stud, washers, bus bar IXb, and nuts from ALT 2 current sensor stand-off.
Installation - ALT 2 Current Sensor
(a)
Acquire necessary tools, equipment, and supplies.
Description
Loctite®
(b)
P/N or Spec.
222
Supplier
Any Source
Purpose
Fuse installation.
Assemble ALT 2 bus bar stud, washers, bus bar IXb, and nuts to ALT 2 current sensor
stand-off.
CAUTION:
Before installing, examine current sensor module for bent pins. If bent pins
are found, gently straighten them.
Do not force current sensor assembly into power board jack. Current sensor
should install into jack with gentle pressure.
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
(m)
(n)
(o)
MCU 14600-002: Align ALT 2 current sensor pins to power board jack while simultaneously aligning bus bar IXb on fuse stud and ALT 2 bus bar stud over terminal ring support
bracket.
MCU 16600-001: Align Alt 2 current sensor module pins to power board jack while simultaneously aligning bus bar IXa on fuse stud and ALT 2 bus bar stud through hole in MCU
chassis.
Gently press ALT 2 current sensor assembly onto power board.
Install screws and washers securing ALT 2 current sensor to power board assembly.
Apply Loctite® to power board fuse studs.
Position 40A fuse to power board assembly and secure with kep-nuts.
MCU 14600-002: Tighten nuts securing ALT 2 bus bar to terminal ring support bracket.
MCU 16600-001: Tighten nuts securing ALT 2 bus bar to MCU chassis.
Connect ALT 2 cable assembly to ALT 2 bus bar stud.
Install MCU cover. (Refer to 24-30)
Connect battery 1. (Refer to 24-30)
Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials w/ MCU 14600-002 & 16600-001
24-30
Page 47
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
L. BAT Current Sensor - Serials w/ MCU 14600-002 & 16600-001 (See Figure 24-3010)
The BAT current sensor, integral to the MCU, is located on the lower mid portion of the power board
assembly.
(1)
Removal - BAT Current Sensor
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) MCU 14600-002: Remove kep-nuts securing 100A fuse to power board assembly.
(f)
MCU 16600-001: Remove kep-nuts securing 125A fuse to power board assembly.
(g) Remove screw, washers, and nut securing bus bar IXc to power board assembly.
(h)
(i)
(j)
(2)
Remove screws and washers securing BAT current sensor to power board assembly.
Remove BAT current sensor from power board assembly.
Disassemble BAT bus bar stud, nuts, washers, bus bar IXc, and bus bar X, from BAT current sensor stand-off.
Installation - BAT Current Sensor
(a)
Acquire necessary tools, equipment, and supplies.
Description
Loctite®
(b)
P/N or Spec.
222
Supplier
Any Source
Purpose
Fuse installation.
Assemble BAT bus bar stud, nuts, washers, bus bar IXc, and bus bar X, to BAT current
sensor stand-off.
CAUTION:
Before installing, examine current sensor module for bent pins. If bent pins
are found, gently straighten them.
Do not force current sensor assembly into power board jack. Current sensor
should install into jack with gentle pressure.
(c)
24-30
Page 48
01 Jan 2016
(d)
(e)
(f)
(g)
(h)
(i)
Align BAT current sensor pins to power board jack while simultaneously aligning bus bar X
on fuse stud.
Gently press BAT current sensor assembly onto power board.
Install screws and washers securing BAT current sensor to power board assembly.
Apply Loctite® to power board fuse studs.
MCU 14600-002: Position 100A fuse to power board assembly and secure with kep-nuts.
MCU 16600-001: Position 125A fuse to power board assembly and secure with kep-nuts.
Install screw, washers, and nut securing bus bar IXc to power board assembly.
(j)
(k)
(l)
(m)
Install MCU cover. (Refer to 24-30)
Connect battery 1. (Refer to 24-30)
Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials w/ MCU 14600-002 & 16600-001
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
M. Logic Module - Serials w/ MCU 14600-002 & 16600-001 (See Figure 24-3010)
The logic module, integral to the MCU, is centrally located on the power board assembly.
(1)
(2)
Removal - Logic Module
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) Remove screws and washers securing logic module to power board assembly.
(f)
Remove logic module from power board assembly.
Installation - Logic Module
CAUTION:
Before installing, examine logic module for bent pins. If bent pins are found, gently
straighten them.
Do not force logic module into power board jack. Logic module should install into
jack with gentle pressure.
(a)
(b)
(c)
(d)
(e)
(f)
Align logic module pins to power board jack and gently press logic module onto power
board.
Install screws and washers securing logic module to power board assembly.
Install MCU cover. (Refer to 24-30)
Connect battery 1. (Refer to 24-30)
Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials w/ MCU 14600-002 & 16600-001
24-30
Page 49
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
N. Midi Fuse - Serials w/ MCU 14600-002 & 16600-001 (See Figure 24-3010)
The midi fuses, integral to the MCU, are installed in five locations on the power board assembly.
(1)
(2)
Removal - Midi Fuse
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) Remove kep-nuts securing midi fuse to power board assembly.
(f)
Remove midi fuse from power board assembly.
Installation - Midi Fuse
(a)
Acquire necessary tools, equipment, and supplies.
Description
Loctite®
(b)
(c)
(d)
(e)
(f)
(g)
(h)
24-30
Page 50
01 Jan 2016
P/N or Spec.
222
Supplier
Any Source
Purpose
Fuse installation.
Apply Loctite® to power board studs.
Position midi fuse on power board studs.
Install kep-nuts securing midi fuse to power board assembly.
Install MCU cover. (Refer to 24-30)
Connect battery 1. (Refer to 24-30)
Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials w/ MCU 14600-002 & 16600-001
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
O. Midi Fuse - Serials w/ MCU 19900-001 (See Figure 24-3010)
The midi fuses, integral to the MCU, are installed in five locations behind the circuit board assembly.
Midi fuses are named in accordance with the attaching bus bar.
(1)
(2)
(3)
(4)
(5)
Removal - Midi Fuse 28
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) Remove circuit board assembly.
(f)
Remove screw and washers securing bus bar 28 to power diode.
(g) Remove nut, washer, and spacers securing bus bar 28 to chassis.
(h) Remove nuts, washers, and spacers securing bus bar 27 to chassis.
(i)
Remove nut, washers, and screw securing fuse to current shunt.
(j)
Remove nut, washers, and screw securing fuse to bus bar 28.
(k)
Remove fuse from MCU.
Installation - Midi Fuse 28
(a) Position fuse to bus bar 28 and secure with screw, washers, and nuts.
(b) Position fuse to current shunt and secure with screw, washers, and nut.
(c)
Position bus bar 27 to chassis and secure with spacers, washers, and nuts.
(d) Position bus bar 28 to chassis and secure with spacers, washer, and nut.
(e) Position bus bar 28 to power diode and secure with screws and washers.
(f)
Install circuit board assembly.
(g) Install MCU cover. (Refer to 24-30)
(h) Connect battery 1. (Refer to 24-30)
(i)
Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
(j)
Install engine cowling. (Refer to 71-10)
Removal - Midi Fuse 18
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) Remove circuit board assembly.
(f)
Remove screw, washers, and nut securing fuse to bus bar 18.
(g) Remove screw securing fuse to power diode.
(h) Remove fuse from MCU.
Installation - Midi Fuse 18
(a) Position fuse to power diode and secure with screw.
(b) Position fuse to bus bar 18 and secure with screw, washers, and nut.
(c)
Install circuit board assembly.
(d) Install MCU cover. (Refer to 24-30)
(e) Connect battery 1. (Refer to 24-30)
(f)
Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
(g) Install engine cowling. (Refer to 71-10)
Removal - Midi Fuse 10
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
EFFECTIVITY:
Serials w/ MCU 19900-001
24-30
Page 51
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
(d) Remove MCU cover. (Refer to 24-30)
(e) Remove circuit board assembly.
(f)
Remove screw, washers, and nut securing fuse to bus bar 10.
(g) Remove screw, washers, and nut securing fuse to current shunt.
(h) Remove fuse from MCU.
(6) Installation - Midi Fuse 10
(a) Position fuse to current shunt and secure with screw, washers, and nut.
(b) Position fuse to bus bar 10 and secure with screw, washers, and nut.
(c)
Install circuit board assembly.
(d) Install MCU cover. (Refer to 24-30)
(e) Connect battery 1. (Refer to 24-30)
(f)
Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
(g) Install engine cowling. (Refer to 71-10)
(7) Removal - Midi Fuse 19
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) Remove circuit board assembly.
(f)
Remove screw, washers, and nut securing fuse to current shunt.
(g) Remove screw securing fuse to power diode.
(h) Remove fuse from MCU.
(8) Installation - Midi Fuse 19
(a) Position fuse to power diode and secure with screw.
(b) Position fuse to current shunt and secure with screw, washers, and nut.
(c)
Install circuit board assembly.
(d) Install MCU cover. (Refer to 24-30)
(e) Connect battery 1. (Refer to 24-30)
(f)
Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
(g) Install engine cowling. (Refer to 71-10)
(9) Removal - Midi Fuse 17
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) Remove circuit board assembly.
(f)
Remove nuts securing 3 bus bar 11s to breakers.
(g) Remove screw securing midi fuse 7 to power diode.
(h) Remove screw securing midi fuse 19 to power diode.
(i)
Remove nut and washers securing bus bar 19 to bus bar 16.
(j)
Remove nuts and washers securing RH clamp to bus bar 14.
(k)
Remove screw, washers, and nut securing fuse to busbar 14.
(l)
Remove screw, washers, and nut securing fuse to busbar 17.
(10) Installation - Midi Fuse 17
(a) Position fuse to busbar 17 and secure with screw, washers, and nut.
(b) Position fuse to busbar 14 and secure with screw, washers, and nut.
(c)
Position bus bar 14 into clamp and secure with washers and nuts.
24-30
Page 52
01 Jan 2016
EFFECTIVITY:
Serials w/ MCU 19900-001
MODEL SR20
CIRRUS
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
Position bus bar 19 to bus bar 16 and secure with washers and nuts.
Position midi fuse 19 to power diode and secure with screw.
Position midi fuse 7 to power diode and secure with screw.
Position 3 bus bar 11s to breakers and secure with nuts.
Install circuit board assembly.
Install MCU cover. (Refer to 24-30)
Connect battery 1. (Refer to 24-30)
Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials w/ MCU 19900-001
24-30
Page 53
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
P. Midi Fuse - Serials w/ MCU 19800-001 (See Figure 24-3010)
The midi fuses, integral to the MCU, are installed in two locations on the power board assembly.
(1)
(2)
24-30
Page 54
01 Jan 2016
Removal - Midi Fuse
(a) Set BAT 1, BAT 2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) Remove screws and washers securing fuse to power board assembly.
Installation - Midi Fuse
(a) Position fuse to power board assembly and secure with screws and washers.
(b) Install MCU cover. (Refer to 24-30)
(c)
Connect battery 1. (Refer to 24-30)
(d) Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
(e) Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials w/ MCU 19800-001
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
Q. Blade Fuse (See Figure 24-3010)
MCU 14600-001, 14600-002, & 16600-001: The blade fuse, integral to the MCU, is located on the
lower LH side of the power board assembly. MCU 19900-001: The blade fuses, integral to the MCU,
are installed in seven locations on the power board assembly. MCU 19800-001: The blade fuses, integral to the MCU, are installed in 21 locations on the power board assembly.
(1)
(2)
Removal - Blade Fuse
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) Remove blade fuse from fuse holder.
Installation - Blade Fuse
(a) Insert blade fuse into fuse holder.
(b) Install MCU cover. (Refer to 24-30)
(c)
Connect battery 1. (Refer to 24-30)
(d) Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
(e) Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
All
24-30
Page 55
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
R. External Fuse (See Figure 24-3010)
MCU 14600-001, 14600-002, 16600-001 & 19900-001: The external fuse, integral to the MCU, is
located on the RH side of the MCU chassis. MCU 19800-001: The external fuse, integral to the MCU,
is located on top of the MCU chassis.
(1)
(2)
24-30
Page 56
01 Jan 2016
Removal - External Fuse
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Remove external fuse from fuse holder assembly.
Installation - External Fuse
(a) Insert external fuse into fuse holder assembly.
(b) Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
(c)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
All
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
S. Field Control Module - Serials w/ MCU 14600-002, 16600-001 (See Figure 24-3010)
The ALT 1 and ALT 2 field control modules, integral to the MCU, are located on the RH side of the
MCU chassis floor.
(1)
(2)
Removal - Field Control Module
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) MCU 16600-001: Remove MCU bottom cover.
(f)
Identify and disconnect wire harness from field control module.
(g) Remove lower screw and washer securing field control module to chassis floor.
(h) Ensure flange on field control module is clear of retainer bar and remove from airplane.
Installation - Field Control Module
Note:
(a)
(b)
(c)
(d)
(e)
(f)
(g)
Do not interchange ALT 1 and ALT 2 field control modules. Verify ALT 1 and ALT 2
field control modules are installed in correct location on chassis floor.
Position field control module with flange under retaining bar, align over installation holes
on chassis floor, and secure with screw and washer.
Connect wire harness to field control module.
MCU 16600-001: Install MCU bottom cover.
Install MCU cover. (Refer to 24-30)
Connect battery 1. (Refer to 24-30)
Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials w/ MCU 14600-002, 16600-001
24-30
Page 57
01 Jan 2016
CIRRUS
T.
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
Field Control Module - Serials w/ MCU 19900-001 (See Figure 24-3010)
The ALT 1 and ALT 2 field control modules are integral to the MCU. The ALT 1 field control module is
located on the lower, RH side of chassis. The ALT 2 field control module is located on the upper, RH
side of chassis floor.
(1)
(2)
(3)
24-30
Page 58
01 Jan 2016
Removal - ALT 1 Field Control Module
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) Remove MCU bottom cover. (Refer to 24-30)
(f)
Remove circuit board assembly. (Refer to 24-30)
(g) Disconnect wire harness from field control module.
(h) Remove screw and washer securing field control module to chassis.
(i)
Slide field control module from under retainer lip. Remove field control module from airplane.
Installation - ALT 1 Field Control Module
(a) Position field control module under retainer lip on chassis and secure with screws and
washers.
(b) Connect wire harness to field control module.
(c)
Install circuit board assembly. (Refer to 24-30)
(d) Install MCU bottom cover. (Refer to 24-30)
(e) Install MCU cover. (Refer to 24-30)
(f)
Connect battery 1. (Refer to 24-30)
(g) Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
(h) Install engine cowling. (Refer to 71-10)
Removal - ALT 2 Field Control Module
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) Remove circuit board assembly. (Refer to 24-30)
(f)
Remove screw securing upper RH standoff to chassis.
(g) Disconnect wire harness from field control module.
(h) Remove screw securing bus bar 8 and terminal ring 736 to power diode.
(i)
Remove nut and spacers securing bus bar 8 to chassis.
(j)
Remove nuts and spacers securing bus bar 9 to chassis.
(k)
Remove bolt, washers, and nuts securing ALT 2 cable and bus bar 9 to chassis.
(l)
Remove or relocate bus bar 8 and bus bar 9 assembly to allow removal of field control
module.
(m) Remove screw and washers securing field control module to chassis.
(n) Slide field control module from under retainer lip. Remove field control module from airplane.
EFFECTIVITY:
Serials w/ MCU 19900-001
CIRRUS
(4)
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
Installation - ALT 2 Field Control Module
(a)
Acquire necessary tools, equipment, and supplies.
Description
Loctite®
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
(m)
(n)
P/N or Spec.
222
Supplier
Any Source
Purpose
Fuse installation.
Position field control module under retainer lip and secure with screws and washers.
Position bus bar 9 to chassis and secure with spacers, washers, and nuts.
Install bolt, washers, and nuts securing alt 2 cable and bus bar 9 to chassis.
Apply Loctite to upper RH standoff and secure to chassis floor with screw. Position sleeve
over standoff.
Position bus bar 8 to chassis and secure with spacers, washers, and nut.
Position bus bar and terminal ring 736 to power diode.
Position circuit board support to standoffs and secure with screws and washers.
Connect wire harness to field control module.
Install circuit board assembly. (Refer to 24-30)
Install MCU cover. (Refer to 24-30)
Connect battery 1. (Refer to 24-30)
Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials w/ MCU 19900-001
24-30
Page 59
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
U. Field Control Module - Serials w/ MCU 19800-001 (See Figure 24-3010)
The ALT 1 and ALT 2 field control modules are integral to the MCU. The ALT 1 field control module is
located on the upper chassis. The ALT 2 field control module is located on the lower, RH side of chassis.
(1)
(2)
24-30
Page 60
01 Jan 2016
Removal - Field Control Module
(a) Set BAT 1, BAT 2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) Disconnect wire harness from field control module.
(f)
Remove nuts securing field control module to chassis. Remove field control module from
airplane.
Installation - Field Control Module
(a) Position field control module to chassis and secure with nuts.
(b) Connect wire harness to field control module.
(c)
Install MCU cover. (Refer to 24-30)
(d) Connect battery 1. (Refer to 24-30)
(e) Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
(f)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials w/ MCU 19800-001
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
V. Circuit Board Assembly - Serials w/ MCU 19900-001 (See Figure 24-3010)
(1)
(2)
Removal - Circuit Board Assembly
(a) Set BAT1, BAT2, and AVIONICS switches to OFF positions.
(b) Remove engine cowling. (Refer to 71-10)
(c)
Disconnect battery 1. (Refer to 24-30)
(d) Remove MCU cover. (Refer to 24-30)
(e) Disconnect P134 and P126 connectors from circuit board.
(f)
Remove screws securing circuit board to mount.
(g) Remove nuts and clamps securing wire harness to mount.
(h) Remove screws securing mount to chassis standoffs.
Installation - Circuit Board Assembly
(a) Position mount to chassis standoffs and secure with screws.
(b) Position circuit board assembly to mount and secure with screws.
(c)
Position wire harness clamps to mount and secure with nuts.
(d) Connect P134 and P126 connectors to circuit board.
(e) Install MCU cover. (Refer to 24-30)
(f)
Connect battery 1. (Refer to 24-30)
(g) Perform Operational Inspection - Master Control Unit. (Refer to 24-30)
(h) Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials w/ MCU 19900-001
24-30
Page 61
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
12
10
4
9
2
7
20
7 6
17
15
7
6
7
6 7
3
2
7
6
2
13
11
6
7
6
19
6
6
5
7
8
7
1
2
LEGEND
1. MCU Cover
2. Screw
3. ALT 1 Current Sensor
4. ALT 1 Cable Assembly
5. Bolt
6. Washer
7. Nut
8. Midi Fuse
9. ALT 2 Current Sensor
10. ALT 2 Cable Assembly
11. BAT Current Sensor
12. Logic Module
13. Blade Fuse
14. External Fuse
15. ALT 1 Field Control Module
16. ALT 2 Field Control Module
17. Bus Bar, IX A
18. Bus Bar, X
19. Bus Bar, IX C
20. Bus Bar, IX B
Serials 1268 thru 1524.
Figure 24-3010
MCU Components - Serials 1268 thru 1524 (Sheet 1 of 5)
24-30
Page 62
01 Jan 2016
14
5
18
6
16
EFFECTIVITY:
Serials 1268 thru 1524
SR20_MM24_1737E
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
26
12
25
24
10
6
20
2
4
9
7
7 6
7
17
15
16
14
7
6
21
6 7
3
13
11
2
6
7
2 6
7
5
18
2
22
6
19
6
6
7
23
6
8
7
1
5
6
23
LEGEND
1. MCU Cover
2. Screw
3. ALT 1 Current Sensor
4. ALT 1 Cable Assembly
5. Bolt
6. Washer
7. Nut
8. Midi Fuse
9. ALT 2 Current Sensor
10. ALT 2 Cable Assembly
11. BAT Current Sensor
12. Logic Module
13. Blade Fuse
2
14. External Fuse
15. ALT 1 Field Control Module
16. ALT 2 Field Control Module
17. Bus Bar, IX A
18. Bus Bar, X
19. Bus Bar, IX C
20. Bus Bar, IX B
21. Spacer
22. Bottom Cover
23. Cable Guide
24. Clamp
25. Loom
26. Cable Tie
2
Serials 1525 thru 1581.
SR20_MM24_2100A
Figure 24-3010
MCU Components - Serials 1525 thru 1581 (Sheet 2 of 5)
EFFECTIVITY:
Serials 1525 thru 1581
24-30
Page 63
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
1
5
4
7
9
8
6
4
10
7
11
14
4
7
6
5
2
12
4
4
13
3
LEGEND
1. Master Control Unit (MCU)
2. Bottom Cable Plate
3. Bottom Cover
4. Screw
5. Clamp
6. Washer
7. Nut
8. Standoff
9. Power Board Mount
10. Power Board
11. Blade Fuse
12. Gasket
13. MCU Cover
14. External Fuse
SR20_MM24_2243
Figure 24-3010
MCU Components - Serials 1582 & subs w/o Perspective Avionics (Sheet 3 of 5)
24-30
Page 64
01 Jan 2016
EFFECTIVITY:
Serials 1582 & subs w/o Perspective Avionics
CIRRUS
AIRPLANE MAINTENANCE MANUAL
6
MODEL SR20
13
4
16
6
16
4
31
16
19
29
24
31
16
28
16
4
23
6
16
6
16
32
30
14
4
15
23
16
6
24
17
25
16
6
27
26
16
19
32
24
4
19
16
19
6
16
23
18
16
22
6
20
16
21
4
33
4
LEGEND
4. Screw
6. Nut
13. ALT 2 Field
Control Module
14. ALT 1 Field
Control Module
15. Busbar Clamp
16. Washer
17. Busbar 14
18. Busbar 17
19. Midi Fuse
20. Busbar 11
21. Busbar 18
22. Busbar 10
23. Current Shunt
24. Insulator
25. Busbar 13
26. Busbar 19
27. Busbar 16
28. Busbar 7
29. Busbar 27
30. Busbar 28
31. Spacer
32. Bolt
33. Breaker
SR20_MM24_2245B
Figure 24-3010
MCU Components - Serials 1582 & subs w/o Perspective Avionics (Sheet 4 of 5)
EFFECTIVITY:
Serials 1582 & subs w/o Perspective Avionics
24-30
Page 65
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
14
14
1
Serials 2016 thru 2240.
15
7
8
2
6
6
7
13
7
16
32
2
21
LEGEND
1. Master Control
Unit (MCU)
2. Screw
6. Washer
7. Nut
8. Midi Fuse
13. Blade Fuse
14. External Fuse
15. ALT 1 Field
Control Module
16. ALT 2 Field
Control Module
21. MCU Cover
22. Spacer
32. Gasket
DETAIL E
SR20_MM24_2906A
Figure 24-3010
MCU Components - Serials 2016 & subs w/ Perspective Avionics (Sheet 5 of 5)
24-30
Page 66
01 Jan 2016
EFFECTIVITY:
Serials 2016 & subs w/ Perspective Avionics
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
W. Low-Volts Warning Light (Annunciator Panel) (Refer to 31-50)
X. ALT 1 and ALT 2 Fail Lights (Refer to 31-50)
Y. Volt / Amp Meter - Serials 1005 thru 1581 (See Figure 24-3011)
(1)
(2)
Removal - Volt / Amp Meter
(a) Set BATTERY and AVIONICS switches to OFF positions.
(b) Serials 1268 thru 1581: Pull BAT 2 circuit breaker to the OFF position.
(c)
Remove engine cowling. (Refer to 71-10)
(d) Disconnect battery 1. (Refer to 24-30)
(e) Remove MFD. (Refer to 31-60)
(f)
Remove screws and washers securing volt / amp meter to instrument panel.
(g) Identify and disconnect wire harness connector from volt / amp meter.
(h) Serials 1005 thru 1502 w/ 100A amp meter after SB 2X-24-04: Disconnect amp meter
adaptor from wire harness connector.
(i)
Remove volt / amp meter from airplane.
Installation - Volt / Amp Meter
Note:
(3)
Volt/amp meter P/N 11240-001 requires adaptor installation between amp meter
and wire harness connector.
(a) Identify and connect wire harness connector to volt / amp meter.
(b) Position volt/amp meter to instrument panel and secure with screws and washers.
(c)
Install MFD. (Refer to 31-60)
(d) Connect battery 1. (Refer to 24-30)
(e) Install engine cowling. (Refer to 71-10)
(f)
Serials 1268 thru 1581: Reset BAT 2 circuit breaker.
(g) Perform Operational Test - Volt / Amp Meter. (Refer to 24-30)
Operational Test - Volt / Amp Meter
(a) Set BAT 1 switch to ON position.
(b) Verify needle indicates 26 ±2 VDC.
(c)
Set BAT 1 switch to OFF position.
EFFECTIVITY:
All
24-30
Page 67
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
Z. Volt / Amp Meter - Serials 1582 & subs (See Figure 24-3011)
Note:
(1)
24-30
Page 68
01 Jan 2016
Voltage and amperage are displayed on the screens of the MFD and PFD.
Operational Test - Volt / Amp Meter
(a) Set BAT1 and AVIONICS switches to ON positions.
(b) On MFD, when PRESS ANY BEZEL KEY TO CONTINUE is displayed, press any key.
(c)
If Engine Monitoring is selected, press [Fuel Done] to enter Map page.
(d) Rotate left knob to select Engine page.
(e) Verify main bus voltage indicates 26 ±2 VDC.
(f)
Verify essential bus voltage indicates no more than 1 vdc less than the main bus voltage.
(g) Verify ALT1 indicates zero amps.
(h) Verify ALT2 indicates zero amps.
(i)
Verify BATT indicates Dschg 0 - 10 amps.
(j)
Turn on large electrical loads (landing light, nav lights, pitot heat, etc.) to ensure more
amps are drawn when larger electrical loads are introduced.
(k)
Verify ammeter indicates an increase in amperage.
(l)
Set BAT1 and AVIONICS switches to OFF positions.
EFFECTIVITY:
Serials 1582 & subs
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
AA.Ammeter Select Switch - Serials 1005 thru 1581 (See Figure 24-3011)
(1)
(2)
(3)
Removal - Ammeter Select Switch
(a) Ensure BATTERY and AVIONICS master switches are in the OFF position.
(b) Serials 1268 thru 1581: Pull BAT 2 circuit breaker to the OFF position.
(c)
Remove engine cowling. (Refer to 71-10)
(d) Disconnect battery 1. (Refer to 24-30)
(e) Remove MFD. (Refer to 31-60)
(f)
Remove screws and washers securing low-volts annunciator to instrument panel.
(g) Identify and disconnect all wires from low-volts annunciator and select switch.
(h) Remove nut and washer securing ammeter select switch to instrument panel. Remove
Low-Volts annunciator and Ammeter Select Switch from instrument panel.
(i)
To disconnect switch, use a solder gun and remove solder from each terminal.
Installation - Ammeter Select Switch
(a) Identify the corresponding wires and place heat shrink tubing into position. Solder all wires
to the corresponding terminal on the switch.
(b) Install screws and washers securing low-volts annunciator to instrument panel.
(c)
Place ammeter select switch into position and secure with washer and nut.
(d) Install MFD. (Refer to 31-60)
(e) Connect battery 1. (Refer to 24-30)
(f)
Install engine cowling.
(g) Serials 1268 thru 1581: Reset BAT 2 circuit breaker.
(h) Perform Operational Test - Ammeter Select Switch. (Refer to 24-30)
Operational Test - Ammeter Select Switch
(a) Set ammeter switch to "BATT".
(b) Ammeter should read 0 to -10 amps.
(c)
Turn on large electrical loads (landing light, nav lights, pitot heat, etc.) to ensure more
amps are drawn when larger electrical loads are introduced.
(d) Verify ammeter indicates an increased discharge.
(e) Set ammeter switch to "ALT1" and "ALT2".
(f)
Ammeter should read “0” in both positions.
EFFECTIVITY:
Serials 1005 thru 1581
24-30
Page 69
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
5
2
4
2
Switch: Serials 1005 thru 1267.
7
5
6
2
3
4
2
Switch: Serials 1268 & subs.
2
1
INSTRUMENT PANEL
(REF)
NOTE
Serials 1005 thru 1502 w/ 100A amp meter
after SB 2X-24-04.
LEGEND
1. Screw
2. Washer
3. Amp Meter
4. Nut
5. Ammeter Select Switch
6. Adaptor
7. Connector
Serials 1005 thru 1581.
Figure 24-3011
Amp Meter Installation - Serials 1005 thru 1581 (Sheet 1 of 3)
24-30
Page 70
01 Jan 2016
EFFECTIVITY:
Serials 1005 thru 1581
SR20_MM24_1776C
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
3
LEGEND
3. Amp Meter
SR20_MM24_2213
Figure 24-3011
Amp Meter Installation - Serials 1582 & subs w/o Perspective Avionics (Sheet 2 of 3)
EFFECTIVITY:
Serials 1582 & subs w/o Perspective Avionics
24-30
Page 71
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
3
ENGINE
PFD w/ ENGINE DISPLAY
3
MFD w/ ENGINE DISPLAY
LEGEND
3. Amp Meter
Serials 2016 & subs w/ Perspective Avionics.
SR20_MM24_2892A
Figure 24-3011
Amp Meter Installation - Serials 2016 & subs w/ Perspective Avionics (Sheet 3 of 3)
24-30
Page 72
01 Jan 2016
EFFECTIVITY:
Serials 2016 & subs w/ Perspective Avionics
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
AB.Turn Coordinator Batteries - Serials 1005 thru 1267 (See Figure 24-3012)
All turn coordinator batteries must be inspected every year for the current expiration date stamp. All
turn coordinator batteries must be replaced prior to the date stamped on the batteries or whenever turn
coordinator power is used. Replace all turn coordinator batteries at the same time and with same expiration date stamp.
(1)
(2)
Removal - Turn Coordinator Batteries
WARNING:
Turn coordinator batteries cannot be recharged, only replaced.
CAUTION:
Ensure electrical power to airplane is off prior to performing maintenance. Do not
use abrasive cleaners or materials to clean battery contacts.
(a) Remove LH kick plate. (Refer to 25-10)
(b) Locate battery tray fastened to under-side flange of bolster panel.
(c)
Pry battery tray from lock strip.
(d) Remove batteries from battery tray.
(e) Examine battery contacts for dirt or corrosion, clean or replace contacts as necessary.
(f)
Record battery replacement date of new cells in Airplane Log Book.
Installation - Turn Coordinator Batteries
(a)
Acquire necessary tools, equipment, and supplies.
Description
Batteries (9 volt)
(b)
(c)
P/N or Spec.
MN1604
Supplier
Duracell
Purpose
Provide emergency power to
turn coordinator.
Install batteries as indicated by battery orientation illustration affixed to inside of battery
case.
Verify correct battery voltage and terminal location to ensure batteries have correct voltage and that they have been installed correctly.
EFFECTIVITY:
Serials 1005 thru 1267
24-30
Page 73
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
1
IGNITION
SWITCH
(REF)
LEGEND
1. Turn Coordinator Battery
Serials 1005 thru 1267.
Figure 24-3012
Turn Coordinator Batteries - Serials 1005 thru 1267
24-30
Page 74
01 Jan 2016
EFFECTIVITY:
Serials 1005 thru 1267
SR20_MM24_1149B
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
AC.Battery 1 (See Figure 24-3013)
(1)
Removal - Battery 1
WARNING:
All electrical circuits must be off, prior to disconnecting battery cables.
Always remove the negative battery cable first, then the positive cable. Insulate cable ends and battery terminals to prevent accidental re-connection.
Remove all jewelry before servicing the battery. Metal objects may fuse to
electrical connections and cause severe burns. Wear face shield and protective clothing when servicing battery and/or handling electrolyte. Neutralize electrolyte spills with a solution of baking soda and water, then rinse
with clean water.
Note:
(a)
(b)
(c)
(d)
The battery box should be washed out thoroughly and dried each time the battery
is removed. Use a non-metallic bristle brush to clean the battery. The battery vent
hose should be inspected periodically for obstructions.
Verify ignition switch is in OFF position and remove the key.
Set BATTERY and AVIONICS switches to OFF positions.
Serials 1268 & subs: Pull BAT 2 circuit breaker.
Remove upper engine cowling. (Refer to 71-10).
CAUTION:
After battery disconnection, insulate cable ends and battery terminals to
prevent accidental connection.
(e)
(f)
(g)
(h)
(i)
(2)
Remove negative battery cable from battery terminal.
Remove positive battery cable from battery terminal.
Insulate cable ends and battery terminals. (Refer to 24-30)
Serials w/ TCM battery: Remove clamp securing vent hose to battery.
Serials 1005 thru 1267: Remove bolts, washers, and cotter pins securing hold-down
bracket to battery mounting tray.
(j)
Serials 1268 & subs: Remove bolts and washers securing hold-down bracket to battery
mounting tray.
(k)
Remove battery hold-down bracket and battery from airplane.
Installation - Battery 1
(a)
Acquire necessary tools, equipment, and supplies.
Description
(b)
(c)
EFFECTIVITY:
All
P/N or Spec.
Supplier
Purpose
Bicarbonate of Soda
(baking soda)
-
Any Source
Neutralize electrolyte.
Contact Cleaner
-
Any Source
Clean terminals.
Acid Resistant Bristle Brush (non-metallic)
Any Source
Clean terminals.
Petroleum Jelly
Any Source
Prevent corrosion.
W-P-236
Rinse battery with fresh water and wipe clean with a dry cloth.
Visually inspect battery box for corrosion and spilled electrolyte.
24-30
Page 75
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
CAUTION:
(d)
(e)
(f)
(g)
(h)
(i)
(j)
Do not allow bicarbonate of soda to enter battery cells or permanent battery
damage will result.
If necessary, clean battery with a solution of bicarbonate of soda and clean water.
Using contact cleaner and bristle brush, remove dirt and corrosion from battery terminals.
Install battery into battery mounting tray, and position battery hold-down bracket to top of
battery.
Serials 1005 thru 1267: Install bolts, washers, and cotter pins securing battery hold-down
bracket to battery mounting tray.
Serials 1268 & subs: Install bolts and washers securing battery hold-down bracket to battery mounting tray. Torque bolts to 10 in-lb (1.1 Nm) greater than accepted nut drag. Maximum torque not to exceed 45 in-lb (5.1 Nm).
Serials w/ TCM battery: Inspect battery vent hose for damage, kinks, or obstructions.
Serials w/ TCM battery: Position battery vent hose to battery and secure with clamp.
CAUTION:
(3)
MODEL SR20
Connecting cables in reverse (positive to negative and negative to positive)
can cause serious damage to the electrical system. Connect the negative
cable last.
(k)
Connect positive battery cable to positive terminal.
(l)
Connect negative battery cable to negative terminal.
(m) To prevent corrosion, apply petroleum jelly to battery terminals.
(n) Install engine cowling. (Refer to 71-10)
(o) Serials 1268 & subs: Pull BAT 2 circuit breaker.
(p) Verify operation of electrical system.
Inspection/Check - Battery 1 Capacity
Note:
Serials w/ TCM Battery: A fully charged battery is considered serviceable if it
meets 80% of the 30 minute emergency capacity rating.
Serials w/ Concorde Battery: A fully charged battery is considered serviceable if it
meets 85% of the nominal rated capacity (C1) shown on the label.
(a)
Acquire necessary tools, equipment, and supplies.
Description
24-Volt Battery Capacity Tester
(4)
24-30
Page 76
01 Jan 2016
P/N or Spec.
-
Supplier
Purpose
Any Source Test battery condition.
(b) Verify ignition switch is in OFF position and remove the key.
(c)
Set BAT 1, BAT 2, and AVIONICS switches to OFF positions.
(d) Pull BAT 2 circuit breaker.
(e) Remove battery 1. (Refer to 24-30)
(f)
Perform capacity test as instructed by the manufacturer.(Refer to 05-10)
(g) If battery fails capacity test, replace battery.
(h) Install battery 1. (Refer to 24-30)
(i)
Reset BAT 2 circuit breaker.
Inspection/Check - Battery 1 Charging - Serials 1005 & subs w/ TCM Battery
If the airplane is parked for long periods of time, the battery may become discharged. The battery may be recharged using a constant-voltage charger.
EFFECTIVITY:
All
CIRRUS
AIRPLANE MAINTENANCE MANUAL
WARNING:
(a)
Do not charge battery in airplane or within 10 feet of a fuel servicing area.
The battery cell caps must be installed during charging.
Acquire necessary tools, equipment, and supplies.
Description
P/N or Spec.
Battery Charger (constantcurrent)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
MODEL SR20
24 Volt
Supplier
Any Source
Purpose
Charge battery.
Verify ignition switch is in OFF position and remove the key.
Set BATTERY and AVIONICS switches to OFF positions.
Remove battery 1. (Refer to 24-30)
Perform Battery 1 Electrolyte Specific Gravity Check. (Refer to 12-10)
Ensure battery cell caps are installed and battery charger is turned off.
Connect battery charger positive lead to positive terminal.
Connect battery charger negative lead to negative terminal.
Set battery charger switch to ON position.
Charge battery at 3-amp rate until cells are gassing. Once cells start gassing, reduce rate
of charge to 1.5 amps.
Note:
Allow 18 to 24 hours to fully charge battery. During charging, maintain electrolyte temperature between 60 - 110°F.
(k)
(5)
Charge battery until voltage and specific gravity readings are constant over three readings
taken at 1/2-hour intervals.
(l)
Set battery charger switch to OFF position. Unplug battery charger.
(m) Disconnect battery charger negative lead.
(n) Disconnect battery charger positive lead.
(o) Install battery 1. (Refer to 24-30)
Inspection/Check - Battery 1 Charging - Serials 2016 & subs w/ Concorde Battery
If the airplane is parked for long periods of time, the battery may become discharged. The battery may be recharged using a constant potential charger.
WARNING:
(a)
Do not charge battery in airplane or within 10 feet of a fuel servicing area.
Acquire necessary tools, equipment, and supplies.
Description
Battery Charger
(constant potential)
CAUTION:
(b)
(c)
(d)
EFFECTIVITY:
All
P/N or Spec.
4142
Supplier
Purpose
Advanced Power Products Charge Battery 1.
Azusa, CA 91702
626-969-7227
Some battery chargers will destroy the battery. Contact manufacturer for
determination of equivalent equipment.
Verify ignition switch is in OFF position and remove the key.
Set BAT 1, BAT 2, and AVIONICS switches to OFF positions.
Remove battery 1. (Refer to 24-30)
24-30
Page 77
01 Jan 2016
CIRRUS
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
(m)
24-30
Page 78
01 Jan 2016
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
Ensure battery charger is turned off.
Connect battery charger positive lead to positive terminal.
Connect battery charger negative lead to negative terminal.
Set battery charger switch to ON position.
Charge battery at 28.2 volts constant potential until charge current stabilizes for 1 hour.
Set battery charger switch to OFF position. Unplug battery charger.
Disconnect battery charger negative lead.
Disconnect battery charger positive lead.
Install battery 1. (Refer to 24-30)
EFFECTIVITY:
All
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
2
3
6
11
FIREWALL
(REF)
10
1
9
3
2
7
3
6
1
9
3
4
2
FIREWALL
(REF)
2
5
3
Serials 1268 thru 1306
before SB 2X-80-01.
8
11
4
10
10
5
9
7
3
9
2
3
11
9
7
2
9
4
2
3
6
10
3
3
2
5
3
Serials 1268 thru 1306
after SB 2X-80-01,
Serials 1307 & subs.
8
1
FIREWALL
(REF)
8
1
2
6
12
Serials 1050 thru 1267.
FIREWALL
(REF)
2
3
11
7
3
4
2
9
9
Serials 1005 thru 1049.
3 2
12
NOTE
Battery drain hose only installed on
airplanes with TCM battery.
LEGEND
1. Battery
2. Bolt
3. Washer
4. Hose Clamp
5. Nut
6. Battery Mounting Tray
7. Vent Hose
8. Hold Down Bracket
9. Adel Clamp
10. Battery Cable, Ground
11. Battery Cable, Power
12. Cotter Pin
SR20_MM24_2061B
Figure 24-3013
Battery 1 Installation
EFFECTIVITY:
All
24-30
Page 79
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
AD.Battery 2 (See Figure 24-3014) - Serials 1268 & subs
(1)
Removal - Battery 2
WARNING:
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
(m)
(n)
(o)
All electrical circuits must be off, prior to disconnecting battery cables. If
battery 2 becomes damaged and electrolyte is spilled, neutralize the spill
immediately with a solution of baking soda and water, then rinse with clean
water.
Verify ignition switch is in OFF position and remove the key.
Set BAT 1, BAT 2, and AVIONICS switches to OFF positions.
Serials 1005 thru 1422: Remove access panel CB6. (Refer to 06-00)
Serials 1423 & subs: Remove access panel RE3. (Refer to 06-00)
Disconnect vent hose from battery enclosure.
Serials 1005 thru 2015, 2016 & subs w/o Perspective Avionics: Disconnect electrical connector from battery enclosure.
Serials 2016 & subs w/ Perspective Avionics: Remove cable ties securing wire harness
service loop to empennage.
Serials 1005 thru 1422: Remove screws and washers securing battery enclosure to
mounting tray standoffs.
Serials 1423 & subs: Remove screws, washers, and spacers securing battery enclosure to
mounting tray.
Serials 1005 thru 2015, 2016 & subs w/o Perspective Avionics: Remove battery enclosure
from airplane.
Serials 2016 & subs w/ Perspective Avionics: Position battery enclosure near access
panel opening.
Remove screws, washers, and nuts securing upper battery enclosure to lower battery
enclosure.
Disconnect negative battery cables from battery terminals.
Disconnect positive battery cables from battery terminals.
Remove batteries from lower enclosure.
CAUTION:
Do not use abrasive cleaners or materials to clean battery terminals.
(p)
(2)
24-30
Page 80
01 Jan 2016
Visually inspect battery terminals for dirt or corrosion. Clean or replace terminals as necessary.
Installation - Battery 2
(a) Position batteries to lower battery enclosure.
(b) Connect positive battery cables to battery terminals.
(c)
Connect negative battery cables to battery terminals.
(d) Position upper battery enclosure to lower battery enclosure and secure with screws,
washers, and nuts.
(e) Serials 1005 thru 1422: Position battery enclosure to mounting tray standoffs and secure
with screws and washers.
(f)
Serials 1423 & subs: Position battery enclosure to mounting tray and secure with screws,
washers, and spacers.
(g) Serials 1005 thru 2015, 2016 & subs w/o Perspective Avionics: Connect electrical connector to battery enclosure.
(h) Serials 2016 & subs w/ Perspective Avionics: Position wire harness service loop to fuselage and secure with cable ties.
(i)
Connect vent hose to battery enclosure.
EFFECTIVITY:
Serials 1268 & subs
CIRRUS
(3)
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
(j)
Serials 1005 thru 1422: Install access panel CB6. (Refer to 06-00)
(k)
Serials 1423 & subs: Install access panel RE3. (Refer to 06-00)
Inspection/Check - Battery 2 Top-Charging
The battery will discharge at approximately 3% per month when storage temperature is maintained at 68° F (20° C). Self-discharge rate will vary with storage temperature and the remaining
capacity. If the battery is going to be stored for extended periods of time, the battery should be
top-charged periodically with a constant-voltage charger.
WARNING:
(a)
Do not charge batteries in airplane or within 10 feet of a fuel servicing area.
Acquire necessary tools, equipment, and supplies.
Description
P/N or Spec.
Battery Charger (constant-voltage) 24 Volt
(b)
(c)
(d)
(e)
(f)
(g)
(h)
Any Source
Purpose
Charge Battery 2.
Verify ignition switch is in OFF position and remove key.
Set BAT 1, BAT 2, and master switches to OFF positions.
Remove battery 2. (Refer to 24-30)
Ensure battery charger is turned off.
Connect battery charger positive lead to positive terminal.
Connect battery charger negative lead to negative terminal.
Set battery charger switch to ON position.
CAUTION:
(i)
(j)
(k)
(l)
(m)
Supplier
In higher temperature areas, the battery should be charged at the lower
voltage of 2.35 volts per cell.
Charge battery at a rate of 2.35 to 2.47 volts per cell (each battery has 6-cells).
Set battery charger switch to OFF position. Unplug battery charger.
Disconnect battery charger negative lead.
Disconnect battery charger positive lead.
Install battery 2. (Refer to 24-30)
EFFECTIVITY:
Serials 1268 & subs
24-30
Page 81
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
13
14
15
10 11 12
16
8
2
17
3
18
2
2
8
1
9
3
2
7
2
3
LEGEND
1. Battery
2. Washer
3. Locknut
4. Standoff
5. Mounting Tray
6. Battery Enclosure, lower
7. Seal
8. Screw
9. Relay
10. Vent Tube
11. Circuit Breaker
12. Bulkhead Fitting
13. Connector
14. Cable Tie
15. Cable Tie Anchor
16. Grommet
17. Battery Enclosure, upper
18. Nut
19. Tab Washer
4
6
5
Serials 1268 thru 1422.
Figure 24-3014
Battery 2 - Serials 1268 thru 1422 (Sheet 1 of 3)
24-30
Page 82
01 Jan 2016
EFFECTIVITY:
Serials 1268 thru 1422
SR20_MM24_1596C
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
8
13
2
14
16
15
8
2
10
12
18
1
17
6
7
2
20
3
18
LEGEND
1. Battery
2. Washer
3. Locknut
5. Mounting Tray
6. Battery Enclosure, lower
7. Seal
8. Screw
9. Relay
10. Vent Tube
11. Circuit Breaker
12. Bulkhead Fitting
13. Connector
14. Cable Tie
15. Cable Tie Anchor
16. Grommet
17. Battery Enclosure, upper
18. Nut
19. Tab Washer
20. Spacer
2
5
19
11
9
8
2
2
3
SR20_MM24_1772
Figure 24-3014
Battery 2 - Serials 1423 thru 2015, 2016 & subs w/o Perspective Avionics (Sheet 2 of 3)
EFFECTIVITY:
Serials 1423 thru 2015, 2016 & subs w/o Perspective
Avionics
24-30
Page 83
01 Jan 2016
CIRRUS
AIRPLANE MAINTENANCE MANUAL
14
16
10
8
2
15
12
MODEL SR20
3
2
3
7
1
17
2
8
20
19
LEGEND
1. Battery
2. Washer
3. Nut
5. Mounting Tray
6. Battery Enclosure, Lower
7. Seal
8. Screw
9. Relay
10. Vent Tube
11. Circuit Breaker
12. Bulkhead Fitting
13. Connector
14. Cable Tie
15. Cable Tie Anchor
16. Grommet
17. Battery Enclosure, Upper
18. Tab Washer
19. Spacer
20. Bolt
21. Bracket
3
2
2
6
3
2
8
2
3
2
18
3
18
9
18
2
13
2
3
18
11
21
Serials 2016 thru 2229.
11
5
Serials w/ Perspective Avionics.
SR20_MM24_2718A
Figure 24-3014
Battery 2 - Serials 2016 & subs w/ Perspective Avionics (Sheet 3 of 3)
24-30
Page 84
01 Jan 2016
EFFECTIVITY:
Serials 2016 & subs w/ Perspective Avionics
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