CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
ELECTRIC FUEL PUMP CONTROL
1. DESCRIPTION
An electric two-speed fuel pump provides boost (low speed) and prime (high speed) for the engine. A console mounted rocker switch located on the center console provides control for the electric fuel pump. The
prime position is momentary. Boost is a non-momentary on position.
Serials 1005 thru 1227 before SB 20-73-02: A fuel pressure based system is used to control boost pump
operation. Both positions of the pump normally operate on the low-speed setting. For engine priming, a
pressure actuated switch located on the fuel injection distribution manifold allows the pump to run on high
speed when fuel system pressure is below 3 PSI. This allows rapid priming of the fuel system for starting.
Once the fuel system is primed, the electric pump is switched to the low-speed setting by the pressure
switch. The boost position operates the electric pump at the low-speed setting only, regardless of fuel system pressure. The boost pump operates on 28 VDC supplied through the 5-amp FUEL PUMP circuit
breaker on Main Bus 2.
Serials 1228 & subs, 1005 thru 1227 after SB 20-73-02: An oil pressure based system is used to control
boost pump operation. The oil pressure/oil temperature gage provides a signal to either the starting circuit
(Serials 1005 thru 1581) or the data acquisition unit (Serials 1582 & subs) to generate a ground for the oil
annunciator and the fuel system. This system allows the fuel pump to run at the prime (high speed) when
the engine oil pressure is less than 10 PSI. Whenever the engine oil pressure exceeds 10 PSI, pressing
the prime switch will have no effect. The boost position operates the electric pump at the low-speed,
regardless of oil pressure. The boost pump operates on 28 VDC supplied through the 5-amp FUEL PUMP
circuit breaker on Main Bus 2.
EFFECTIVITY:
All
73-20
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15 Jun 2010
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
2. MAINTENANCE PRACTICES
A. Fuel Pressure Switch - Serials 1005 thru 1227 before SB 20-73-02 (See Figure 73-201)
(1)
(2)
73-20
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15 Jun 2010
Removal - Fuel Pressure Switch
(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) Loosen fuel distribution manifold valve from engine.
(e) Disconnect connector from fuel pressure switch assembly.
(f)
Remove screws and washers securing terminal rings to landing light assembly, if applicable.
(g) Remove fuel pressure switch assembly from fuel distribution manifold valve.
Installation - Fuel Pressure Switch
(a) Install fuel pressure switch to fuel distribution manifold valve.
(b) Install screws and washers securing terminal rings to landing light assembly, if applicable.
(c)
Connect connector from fuel pressure switch assembly.
(d) Tighten fuel distribution manifold valve to engine.
(e) Connect battery 1. (Refer to 24-30)
(f)
Install engine cowling. (Refer to 71-10)
EFFECTIVITY:
Serials 1005 thru 1227 before SB 20-73-02
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
B. Starting Circuit Assembly - Serials 1228 thru 1581, 1005 thru 1227 after SB 20-73-02 (See Figure
73-201)
(1)
(2)
Removal - Starting Circuit Assembly
(a) Set BAT 1, BAT 2, and AVIONICS switches to OFF positions.
(b) Remove glareshield. (Refer to 25-10)
(c)
Disconnect and disassemble firewall ground connector J100.
(d) Disconnect pin 18 and wire IESC1024-22 from connector J100.
(e) Disconnect starting circuit assembly from oil pressure/temperature gage and connector
P650. Remove starting circuit assembly from airplane.
Installation - Starting Circuit Assembly
(a) Install pin 18 and wire IESC1024-22 to connector J100.
(b) Reassemble connector J100 and install to connector P100.
(c)
Connect starting circuit assembly to oil pressure/temperature gage and connector P650.
(d) Install glareshield. (Refer to 25-10)
EFFECTIVITY:
Serials 1228 thru 1581, 1005 thru 1227 after SB 20-7302
73-20
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15 Jun 2010
CIRRUS
AIRPLANE MAINTENANCE MANUAL
MODEL SR20
FUEL MANIFOLD VALVE
(REF)
2
Serials 1005 thru 1227 before SB 20-73-02.
P650
(REF)
1
OIL PRESSURE/TEMPERATURE
GAGE (REF)
P100
(REF)
FIREWALL
(REF)
Serials 1228 thru 1581, 1005 thru 1227 after SB 20-73-02.
LEGEND
1. Starting Circuit Assembly
2. Fuel Pressure Switch
SR20_MM73_1531B
Figure 73-201
Fuel Pressure Switch and Starting Circuit Assembly Installation - Serials 1005 thru 1581
73-20
Page 4
15 Jun 2010
EFFECTIVITY:
Serials 1005 thru 1581