CIRRUS AIRPLANE MAINTENANCE MANUAL Fuel CHAPTER 28-00: GENERAL 28-00: 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 (SR22 Serials: 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 layout: (See Figure 28-00-1) Fuel system schematic: (See Figure 28-00-2) (See Figure 28-00-3) 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) 1
CHAPTER 28-00: 2. Troubleshooting CIRRUS AIRPLANE MAINTENANCE MANUAL Trouble Probable Cause Remedy Filler cap leaks. Filler cap improperly installed. Install filler cap properly. Seal improperly installed. Deteriorated seal. Improperly tightened cap fuel nuts. Replace fuel cap seal. Replace fuel cap seal. Tighten or loosen fuel cap nuts as required. Fuel connector(s) leak. Loose connector(s). Inspect and tighten connector(s). Defective seals. Defective thread. Replace seals. Replace threaded component. Insufficient fuel flow. Restricted fuel filter/screen. Clean filter or screen. Normal starting procedures result in difficult starting. No fuel flow to engine driven fuel pump. Defective mechanical fuel pump. Defective fuel pressure sensor or insufficient voltage supplied. Cracked fuel line. Faulty electric fuel pump. Fuel selector valve not in the on position. Fuel tanks empty. Fuel line disconnected or broken. Fuel tank screen plugged. Defective fuel selector valve. Plugged gascolator. Fuel line plugged. Frozen fuel line. Replace pump. Replace pressure sensor. Find voltage problem. Replace line. Replace pump. Turn selector valve on. Fill tanks with approved fuel. Repair or replace line. Clean or replace screen. Replace selector valve. Clean or replace gascolator. Remove obstruction. Thaw and drain complete fuel system. 2
CIRRUS AIRPLANE MAINTENANCE MANUAL CHAPTER 28-00: Trouble Probable Cause Remedy Fuel starvation after start up. Insufficient fuel flow. See remedies from above. No fuel output indicated from fuel flow gage when auxiliary pump is 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 quantity indicator indicates inaccurate fuel level. Malfunction of engine-driven fuel pump or fuel system. Fuel vents plugged. Water in fuel. Mixture control set in lean position and throttle lever is pulled back. Fuel line disconnected before fuel flow sensor. Defective fuel pump switch. Open or defective circuit breaker. Loose connections or open circuit. Defective electric fuel pump. Defective engine-driven fuel pump bypass or defective fuel system. Defective fuel sensor. Incorrectly adjusted fuel sensor. Faulty fuel system wiring. Replace pump. Remove obstruction. Remove water. Adjust mixture control richer and move throttle lever forward. Check all fuel lines and connect. Replace switch. Reset or replace circuit breaker. Tighten connections/repair wire. Replace pump. Replace pump/troubleshoot fuel system. Replace sensor. Adjust sensor. Repair/Replace wire(s). Defective engine airframe unit. Replace GEA 71. (Refer to 77-40) 3
CHAPTER 28-00: CIRRUS AIRPLANE MAINTENANCE MANUAL Trouble Probable Cause Remedy No fuel quantity indication. Fuel tanks empty. Fill with approved fuel. QTY circuit breaker open or defective. Loose connections or open circuit. Reset or replace circuit breaker. Tighten connections/repair wire. Incorrect power to fuel level indicator in console. 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 voltage between pins 1 & 9 measures between ~24-28v. Check airplane power source and resolve. 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). Check continuity in airplane wire harness between indicator and sending units. Perform Adjustment/Test - Fuel Quantity Indication. (Refer to 28-40) Defective fuel sensor. Defective fuel quantity indicator. Incorrectly adjusted fuel sensor. Faulty fuel system wiring. Replace sensor. Replace indicator. Adjust sensor. Repair/Replace wire(s). Defective engine airframe unit. Replace GEA 71. (Refer to 77-40) 4
CIRRUS AIRPLANE MAINTENANCE MANUAL CHAPTER 28-00: Trouble Probable Cause Remedy Fluctuating fuel level indications. Incorrect power to fuel level indicator in console. Disconnect airplane harness from indicator and verify voltage between pins 1 & 9 measures between ~24-28v. Resistance to fuel level indicator from fuel level sending units are unstable and/or greater than 70 ohms (depending on fuel level). Check airplane power source and resolve. 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). Check continuity in airplane wire harness between indicator and sending units. Perform Adjustment/Test - Fuel Quantity Indication. (Refer to 28-40) Fluctuating fuel flow indications. Fuel flow indicator/transducer. Replace fuel flow indicator/transducer. Fuel leaks from electric fuel pump drain manifold fitting. Vapor in fuel lines. Faulty internal fuel pump seal. Turn on auxiliary fuel pump. Replace electric fuel pump. 5
CHAPTER 28-00: CIRRUS AIRPLANE MAINTENANCE MANUAL Figure 28-00-1: Fuel System 5 7 9 4 3 2 8 6 1 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_4490 6
CIRRUS AIRPLANE MAINTENANCE MANUAL Figure 28-00-2: Fuel System Schematic - SR22 Serials VENT FILLER ANNUNCIATOR MFD INDICATION FILLER CHAPTER 28-00: VENT L. WING TANK R. WING TANK L. WING COLLECTOR R. WING COLLECTOR CHECK CHECK FLAPPER SELECTOR FLAPPER DRAIN (5 PLACES) FIREWALL SELECTOR OPERATIO N ELECTRIC AUXILIARY PUMP RELAY BOOST PUMP RIGHT RETURN FEED ENGINE DRIVEN PUMP MIXTURE CNTL. GASCOLATOR PRIME OIL PRESSURE SENSOR (LOW PRESSURE) RETURN FEED LEFT ENGINE AIRFRAME UNIT OFF THROTTLE METERING NOTE In Prime mode, relay allows high-speed pump operation until 10 psi oil pressure is reached then drops to low-speed operation. PRESSURE SWITCH INJECTOR MANIFOLD FLOW INDICATOR SR22_MM28_4491 7
CHAPTER 28-00: CIRRUS AIRPLANE MAINTENANCE MANUAL Figure 28-00-3: Fuel System Schematic - SR22T Serials VENT FILLER ANNUNCIATOR MFD INDICATION FILLER VENT L. WING TANK R. WING TANK L. WING COLLECTOR R. WING COLLECTOR FLAPPER SELECTOR FLAPPER DRAIN (5 PLACES) FIREWALL SELECTOR OPERATIO N ELECTRIC AUXILIARY PUMP RELAY BOOST PUMP RIGHT RETURN FEED ENGINE DRIVEN PUMP MIXTURE CNTL. GASCOLATOR HIGH BOOST/ PRIME ENGINE SPEED SENSOR (LOW RPM) RETURN FEED LEFT OFF ENGINE AIRFRAME UNIT MAP SENSOR (HIGH in Hg) 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. THROTTLE METERING PRESSURE SWITCH INJECTOR MANIFOLD FLOW INDICATOR SR22_MM28_4492 8