CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODELS SR22 AND SR22T
FUEL
1. GENERAL
This chapter contains information on the storage, distribution, and indicating components of the fuel system.
The engine is supplied with fuel drawn out of the left or right integral fuel tank (depending on the fuel selector valve position). Fuel flows through a flapper assembly (Serials 22-0002 & subs: swing check valve),
integral collector tank, selector valve, electric auxiliary fuel pump, gascolator, engine-driven fuel pump, fuel
flow sensor, throttle body, fuel injection manifold, and is then distributed to the fuel nozzles. All fuel line fittings installed in the cabin area of the fuselage are enclosed in a vented and drained enclosure.
Fuel system troubleshooting flowchart: (See Figure 28-001)
Fuel system layout: (See Figure 28-002)
Fuel system schematic: (See Figure 28-003)
For maintenance practices pertinent to the engine-driven fuel pump, fuel flow sensor, and fuel nozzles
refer to Chapter 73, Engine Fuel Systems. (Refer to 73-00)
EFFECTIVITY:
All
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15 Jun 2010
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODELS SR22 AND SR22T
2. TROUBLESHOOTING
Trouble
Filler cap leaks.
Fuel connector(s) leak.
Insufficient fuel flow.
Probable Cause
Remedy
Filler cap improperly installed.
Install filler cap properly.
Seal improperly installed.
Replace fuel cap seal.
Deteriorated seal.
Replace fuel cap seal.
Improperly tightened cap fuel
nuts.
Tighten or loosen fuel cap nuts as
required.
Loose connector(s).
Inspect and tighten connector(s).
Defective seals.
Replace seals.
Defective thread.
Replace threaded component.
Restricted fuel filter/screen.
Clean filter or screen.
Defective mechanical fuel pump.
Replace pump.
Defective fuel pressure sensor or Replace pressure sensor.
insufficient voltage supplied.
Find voltage problem.
Cracked fuel line.
Replace line.
Normal starting procedures result Faulty electric fuel pump.
in difficult starting.
Replace pump.
No fuel flow to engine driven fuel
pump.
Fuel selector valve not in the on
position.
Turn selector valve on.
Fuel tanks empty.
Fill tanks with approve fuel.
Fuel line disconnected or broken. Repair or replace line.
Fuel starvation after start up.
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01 Jan 2016
Fuel tank screen plugged.
Clean or replace screen.
Defective fuel selector valve.
Replace selector valve.
Plugged gascolator.
Clean or replace gascolator.
Fuel line plugged.
Remove obstruction.
Frozen fuel line.
Thaw and drain complete fuel system.
Insufficient fuel flow.
See remedies from above.
Malfunction of engine-driven fuel
pump or fuel system.
Replace pump.
Fuel vents plugged.
Remove obstruction.
Water in fuel.
Remove water.
EFFECTIVITY:
All
CIRRUS
AIRPLANE MAINTENANCE MANUAL
Trouble
Probable Cause
MODELS SR22 AND SR22T
Remedy
No fuel output indicated from fuel Mixture control set in lean position Adjust mixture control richer and
move throttle lever forward.
flow gage when auxiliary pump is and throttle lever is pulled back.
operated.
NOTE: If the auxiliary pump is
turned on when the engine is off,
the fuel flow gage will show a
momentary fuel flow.
Fuel line disconnected before fuel Check all fuel lines and connect.
flow sensor.
Defective fuel pump switch.
Replace switch.
Open or defective circuit breaker. Reset or replace circuit breaker.
Loose connections or open circuit. Tighten connections/Repair wire.
Defective electric fuel pump.
Replace pump.
Defective engine-driven fuel pump Replace pump/troubleshoot fuel
bypass or defective fuel system. system.
EFFECTIVITY:
All
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15 Jun 2010
CIRRUS
AIRPLANE MAINTENANCE MANUAL
Trouble
Fuel quantity indicator indicates
inaccurate fuel level.
Probable Cause
Resistance to fuel level indicator
from fuel level sending units are
unstable and/or greater than 70
ohms (depending on fuel level).
MODELS SR22 AND SR22T
Remedy
Disconnect airplane harness from
console indicator and verify resistance of RH wing (pins 4 & 9) and
LH wing (pins 2 & 9) is stable and
measures between 0-70 ohms
(depending on fuel level).
Perform System Test - Fuel Sending Unit. (Refer to 28-40)
Check continuity in airplane wire
harness between indicator and
sending units.
Perform Adjustment/Test - Fuel
Quantity Indicator. (Refer to 2840)
Resistance of each fuel level
sender dial from inboard through
outboard locations are unstable
and/or greater than 35 ohms
(depending on fuel level).
Verify resistance from inboard
through outboard fuel level sender
dials are stable and between 0-35
ohms depending on fuel level.
Perform Functional Test - Fuel
Quantity Sensor Dial. (Refer to 2840)
Perform System Test - Fuel Sending Unit. (Refer to 28-40)
Perform Adjustment/Test - Fuel
Quantity Sensors. (Refer to 28-40)
Fuel level out of calibration.
Adjust calibration using fuel indicator trim adjustments.
If unable to calibrate, ensure both
sending units indicate “E” at zero
calibration and maximum at high
gain.
Perform Adjustment/Test - Fuel
Quantity Indicator. (Refer to 2840)
Note: Indicator has active dampening. Allow indicator to stabilize
for approximately one minute
before making adjustments.
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15 Jun 2010
Defective fuel sensor.
Replace sensor.
Defective fuel quantity indicator.
Replace indicator.
Incorrectly adjusted fuel sensor.
Adjust sensor.
Faulty fuel system wiring.
Repair/Replace wire(s).
EFFECTIVITY:
All
CIRRUS
AIRPLANE MAINTENANCE MANUAL
Trouble
No fuel quantity indication.
Probable Cause
MODELS SR22 AND SR22T
Remedy
Fuel tanks empty.
Fill with approved fuel.
Left or right fuel tank circuit
breaker open or defective.
Reset or replace circuit breaker.
Loose connections or open circuit. Tighten connections/repair wire.
Incorrect power to fuel level indicator in console.
Disconnect airplane harness from
indicator and verify voltage
between pins 1 & 9 measures
between ~24-28v.
Check airplane power source and
resolve.
Resistance to fuel level indicator
from fuel level sending units are
unstable and/or greater than 70
ohms (depending on fuel level).
Disconnect airplane harness from
indicator and verify resistance of
RH wing (pins 4 & 9) and LH wing
(pins 2 & 9) is stable and measures between 0-70 ohms
(depending on fuel level).
Perform Functional Test - Fuel
Quantity Sensor Dial. (Refer to 2840)
Perform System Test - Fuel Sending Unit. (Refer to 28-40)
Check continuity in airplane wire
harness between indicator and
sending units.
Perform Adjustment/Test - Fuel
Quantity Indicator. (Refer to 2840)
EFFECTIVITY:
All
Defective fuel sensor.
Replace sensor.
Defective fuel quantity indicator.
Replace indicator.
Incorrectly adjusted fuel sensor.
Adjust sensor.
Faulty fuel system wiring.
Repair/Replace wire(s).
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15 Jun 2010
CIRRUS
AIRPLANE MAINTENANCE MANUAL
Trouble
Fluctuating fuel level indications.
Probable Cause
Incorrect power to fuel level indicator in console.
MODELS SR22 AND SR22T
Remedy
Disconnect airplane harness from
indicator and verify voltage
between pins 1 & 9 measures
between ~24-28v.
Check airplane power source and
resolve.
Resistance to fuel level indicator
from fuel level sending units are
unstable and/or greater than 70
ohms (depending on fuel level).
Disconnect airplane harness from
console indicator and verify resistance of RH wing (pins 4 & 9) and
LH wing (pins 2 & 9) is stable and
measures between 0-70 ohms
(depending on fuel level).
Perform Functional Test - Fuel
Quantity Sensor Dial. (Refer to 2840)
Perform System Test - Fuel Sending Unit. (Refer to 28-40)
Check continuity in airplane wire
harness between indicator and
sending units.
Perform Adjustment/Test - Fuel
Quantity Indicator. (Refer to 2840)
Resistance of each fuel level
sender dial from inboard through
outboard locations are unstable
and/or greater than 35 ohms
(depending on fuel level).
Verify resistance from inboard
through outboard fuel level sender
dials are stable and between 0-35
ohms depending on fuel level.
Perform System Test - Fuel Sending Unit. (Refer to 28-40)
Perform Adjustment/Test - Fuel
Quantity Sensors. (Refer to 28-40)
Fluctuating fuel flow indications.
Fuel flow indicator/transducer.
Replace fuel flow indicator/transducer.
Vapor in fuel lines.
Turn on auxiliary fuel pump.
Fuel leaks from electric fuel pump Faulty internal fuel pump seal.
drain manifold fitting.
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15 Jun 2010
EFFECTIVITY:
All
Replace electric fuel pump.
CIRRUS
AIRPLANE MAINTENANCE MANUAL
1
Failure to
display fuel
level?
YES
STEP 1A
Check power to
fuel level
indicator in
console:
Disconnect
airplane harness
from indicator.
STEP 1B
Check resistance to
fuel level indicator
from fuel level
sending units:
YES
MODELS SR22 AND SR22T
Measure
voltage between
pins 1 & 9.
Approximately
24 ˇ 28V?
NO
Stable and
between 0-70
Ohms?
NO
Check airplane
power
source and
resolve.
NO
Measure
resistance of RH
wing (pins 4 & 9)
and LH wing (pins
2 & 9).
Disconnect
airplane
harness from
console
indicator.
Troubleshoot Fuel
Level Sender
Assembly.
YES
2
Fluctuating
fuel level
indicator?
YES
Perform STEP 1A
Perform STEP 1B
Check continuity in
airplane wire
harness between
indicator and
sending units.
Troubleshoot Fuel
Level Indicator.
STEP 2C
Check resistance
of each fuel level
sender dial:
NO
Measure
resistance starting
inboard and move
outboard.
3
Faulty fuel level
indication?
Troubleshoot Fuel
Level Indicator.
NO
Troubleshoot Fuel
Level Sender
Assembly.
YES
NO
YES
Stable and
between 0-35
Ohms?
Perform STEP 1B
YES
Perform STEP 2C
STEP 3C
Perform fuel level
calibration:
Calibration
OK?
Allow indicator to
stabilize for ~1
minute before
making
adjustments.
Perform
Adjustment/Test ˇ
Fuel Quantity
Indicator.
(Refer to 28-40)
NO
Troubleshoot Fuel
Level Sender
Assembly.
Adjust calibration
using fuel
indicator trim
adjustments.
Ensure sending
units show “E” at
zero calibration &
high gain backed
just off max.
SR22_MM28_3326
Figure 28-001
Fuel System Troubleshooting Flowchart (Sheet 1 of 3)
EFFECTIVITY:
All
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15 Jun 2010
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODELS SR22 AND SR22T
Troubleshoot Fuel
Level Indicator
2.2 ohms = p/n 38K5441
18 ohms = p/n 38K5430
24 ohms = p/n 38K5446
36 ohms = p/n 38K5467
62 ohms = p/n 38K5498
Obtain axial lead
resistors from
Newark or any
source.
Resistors must be
0.1 - 0.125W
power rating and a
accuracy tolerance
+/-1.
Connect 24-28v
DC power to
indicator:
(+) = Pin 1
(gnd) = Pin 9
Connect resistor to
indicator:
Left = Pins 2 & 9
Right = Pins 4 & 9
Verify needle
position. Needle
position can vary
2-3 gallons.
Ohms vs.
gallons
correct?
NO
2.2 ohms = 0 gal
18 ohms = 10 gal
24 ohms = 20 gal
36 ohms = 30 gal
62 ohms = full
If indicator
calibration is
not correct, values
will vary.
Perform bench
level calibration on
gage.
Adjust low gain
screw fully to
counterclockwise
position.
Adjust high gain to
half way between
clockwise and
counterclockwise
position.
Connect resistors
to gage again.
Other resistors
match chart?
Adjust low/high
pots as necessary
to have needle
show 0 and full.
YES
Fuel Level
Indicator functions
correctly.
YES
NO
Indicator is
defective.
Replace Fuel
Level Indicator.
(Refer to 28-40)
SR22_MM28_3328
Figure 28-001
Fuel System Troubleshooting Flowchart (Sheet 2 of 3)
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15 Jun 2010
EFFECTIVITY:
All
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODELS SR22 AND SR22T
Troubleshoot Fuel
Level Sender Assy
Access inboard
and outboard
sending units
through wing
access panels.
Disconnect
sending unit from
airplane
wire harness.
Take initial
readings. Shake
wing, allow fuel to
settle, and
re-take readings.
Measure
resistance from
sending unit dial
as installed.
Stable?
NO
Dial is defective.
Replace Fuel
Level Sender Dial.
(Refer to 28-40)
NO
Dial is defective.
Replace Fuel
Level Sender Dial.
(Refer to 28-40)
YES
Between
0-35 Ohms?
Dial is defective.
Replace Fuel
Level Sender Dial.
(Refer to 28-40)
YES
Operative?
NO
NO
Connect dial to
multimeter or
ohmmeter to
observe
resistance.
Use metallic object
(i.e. steel ruler,
rod, bar) to bottom
out dial needle at
“E” empty.
Remove Fuel
Level Sender Dial.
(Refer to 28-40)
YES
Remove Fuel
Level Float
Assembly and
inspect.
Install Fuel Level
Sender Dial.
(Refer to 28-40)
Resistance
between 0-3.5
ohms?
YES
Values
bounce slightly
(~ ±2ohm)?
NO
Values
bounce greatly
(> 2ohm)?
NO
Values
>35 ohms at
full or during
sweep?
YES
YES
YES
Dial is OK for
installation.
Dial is defective.
Replace Fuel
Level Sender Dial.
(Refer to 28-40)
Dial is defective.
Replace Fuel
Level Sender Dial.
(Refer to 28-40)
Rotate metallic
object slowly and
watch resistance
on ohmmeter.
SR22_MM28_3330
Figure 28-001
Fuel System Troubleshooting Flowchart (Sheet 3 of 3)
EFFECTIVITY:
All
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15 Jun 2010
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODELS SR22 AND SR22T
5
8
4
9
3
2
6
7
1
Serials 22-0002 thru 22-2333,
22-2335 thru 22-2419, 22-2421 thru 22-2437.
LEGEND
1. Fuel System Vent, NACA
(Underside of Wing)
2. Fuel Tank
3. Fuel Tank Strainers
4. Collector Tank
5. Selector Valve
6. Fuel Gage
7. Engine Driven Fuel Pump
8. Gascolator
9. Electric Boost Pump
SR22_MM28_1344A
Figure 28-002
Fuel System - Serials 22-0002 thru 22-2437 (Sheet 1 of 2)
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Page 10
15 Jun 2010
EFFECTIVITY:
Serials 22-0002 thru 22-2437
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODELS SR22 AND SR22T
5
4
9
3
2
7
6
1
8
LEGEND
1. Fuel System Vent, NACA
(Underside of Wing)
2. Fuel Tank
3. Fuel Tank Strainers
4. Collector Tank
5. Selector Valve
6. Fuel Gage
7. Engine Driven Fuel Pump
8. Gascolator
9. Electric Boost Pump
SR22_MM28_2563A
Figure 28-002
Fuel System - Serials 22-2438 & subs, 22T-0001 & subs (Sheet 2 of 2)
EFFECTIVITY:
Serials 22-2438 & subs, 22T-0001 & subs
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15 Jun 2010
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODELS SR22 AND SR22T
ANNUNCIATOR
FUEL
VENT
FUEL
QUANTITY
INDICATOR
FILLER
L. WING TANK
R. WING TANK
R. WING
COLLECTOR
L. WING
COLLECTOR
SELECTOR
VALVE
FLAPPER
VALVE
DRAIN
(5 PLACES)
RIGHT
RETURN
FLAPPER
VALVE
FIREWALL
ELECTRIC
AUXILIARY
PUMP
SELECTOR VALVE
OPERATION
FUEL
RELAY
FUEL
PUMP
OIL
PRESSURE
SENSOR
(LOW PRESSURE)
PRIME
RETURN
FEED
BOOST
GASCOLATOR
ENGINE
DRIVEN
FUEL PUMP
MIXTURE CNTL.
LEFT
FEED
FUEL
FLOW
INDICATOR
STARTING
CIRCUIT / DAU
Serials 22-0278 and subs,
22-0002 thru 22-0277 after SB 22-73-01.
TO
SELECTOR
VALVE
OFF
NOTE
In Prime mode, relay allows
high-speed pump operation until
10 psi oil pressure is reached then
drops to low-speed operation.
In Prime mode, relay allows
high-speed pump operation
until 2-4 psi fuel pressure is
reached then drops to
low-speed operation.
THROTTLE
METERING
VALVE
FUEL
BOOST
RELAY
ELECTRIC
AUXILIARY
PUMP
Page 12
15 Jun 2010
FUEL
PUMP
PRIME
INJECTOR
MANIFOLD
TO
GASCOLATOR
Serials 22-0002 thru 22-0277 before SB 22-73-01.
FUEL PRESSURE SWITCH
Serials 22-0002 thru 22-2333, 22-2335 thru 22-2419, 22-2420 thru 22-2437.
Figure 28-003
Fuel System Schematic - Serials 22-0002 thru 22-2437 (Sheet 1 of 3)
28-00
VENT
FILLER
EFFECTIVITY:
Serials 22-0002 thru 22-2437
SR22_MM28_1350E
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODELS SR22 AND SR22T
ANNUNCIATOR
FUEL
VENT
FUEL
QUANTITY
INDICATOR
FILLER
VENT
FILLER
L. WING TANK
R. WING TANK
R. WING
COLLECTOR
L. WING
COLLECTOR
CHECK
VALVE
CHECK
VALVE
SELECTOR
VALVE
FLAPPER
VALVE
FLAPPER
VALVE
DRAIN
(5 PLACES)
FIREWALL
ELECTRIC
AUXILIARY
PUMP
SELECTOR VALVE
OPERATIO N
RIGHT
RETURN
FUEL
RELAY
FUEL
PUMP
PRIME
RETURN
FEED
BOOST
GASCOLATOR
OIL
PRESSURE
SENSOR
(LOW PRESSURE)
ENGINE
DRIVEN
FUEL PUMP
MIXTURE CNTL.
LEFT
FEED
STARTING
CIRCUIT / DAU / GEA 71
OFF
FUEL
FLOW
INDICATOR
THROTTLE
METERING
VALVE
NOTE
In Prime mode, relay allows
high-speed pump operation until
10 psi oil pressure is reached then
drops to low-speed operation.
INJECTOR
MANIFOLD
FUEL PRESSURE
SWITCH
SR22_MM28_2392A
Figure 28-003
Fuel System Schematic - Serials 22-2438 & subs (Sheet 2 of 3)
EFFECTIVITY:
Serials 22-2438 & subs
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15 Jun 2010
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODELS SR22 AND SR22T
ANNUNCIATOR
FUEL
VENT
FUEL
QUANTITY
INDICATOR
FILLER
VENT
FILLER
L. WING TANK
R. WING TANK
R. WING
COLLECTOR
L. WING
COLLECTOR
SELECTOR
VALVE
FLAPPER
VALVE
DRAIN
(5 PLACES)
FIREWALL
ELECTRIC
AUXILIARY
PUMP
SELECTOR VALVE
OPERATIO N
RIGHT
RETURN
FLAPPER
VALVE
FUEL
RELAY
FUEL
PUMP
HIGH
BOOST/
PRIME
RETURN
FEED
BOOST
GASCOLATOR
ENGINE
DRIVEN
FUEL PUMP
MIXTURE CNTL.
ENGINE SPEED
SENSOR
(LOW RPM)
LEFT
FEED
ENGINE
AIRFRAME
UNIT
MAP SENSOR
(HIGH in Hg)
OFF
THROTTLE
METERING
VALVE
NOTE
In HIGH BOOST/PRIME
mode, relay allows fuel
pump operation only when
manifold pressure is greater
than 24 in Hg or, - to
facilitate engine starting
- when engine speed is
less than 500 RPM.
INJECTOR
MANIFOLD
FUEL PRESSURE
SWITCH
Figure 28-003
Fuel System Schematic - Serials 22T-0001 & subs (Sheet 3 of 3)
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Page 14
15 Jun 2010
EFFECTIVITY:
Serials 22T-0001 & subs
FUEL FLOW
INDICATOR
SR22_MM28_3265