Fuel Metering Systems Flashcards
- If the main air bleed of a float-type carburetor becomes clogged, the engine will run
a. lean at rated power
b. rich at rated power
c. rich at idling
b.
- One of the best ways to increase engine power and control detonation and preignition is to
a. enrich the fuel/air mixture
b. use water injection
c. lean the fuel/air mixture
b.
- One purpose of an air bleed in a float-type carburetor is to
a. increase fuel flow at altitude
b. meter air to adjust the mixture
c. decrease fuel density and destroy surface tension
c.
- An excessively lean fuel/air mixture may cause
a. an increase in cylinder head temperature
b. high oil pressure
c. backfiring through the exhaust
a.
- When checking the idle mixture on a carburetor, the engine should be idling normally, then pull the mixture control toward the IDLE CUTOFF position. A correct idling mixture will be indicated by
a. an immediate decrease in RPM
b. a decrease of 20 to 30 RPM before quitting
c. an increase of 10 to 50 RPM before decreasing
c.
- Detonation occurs when the fuel/air mixture
a. burns too fast
b. ignites before the time of normal ignition
c. is too rich
a.
- What component is used to ensure fuel delivery during periods of rapid engine acceleration?
a. Acceleration pump
b. Water injection pump
c. Power enrichment unit
a.
- In order to stabilize cams, springs, and linkages within the fuel control, manufacturers generally recommend that all final turbine engine trim adjustments be made in the
a. increase direction
b. decrease direction
c. decrease direction after over-adjustment
a.
- If the idling jet becomes clogged in a float-type carburetor, the
a. engine operation will not be affected at any RPM
b. engine will not idle
c. idle mixture becomes richer
b.
- A carburetor is prevented from leaning out during quick acceleration by the
a. enrichment system
b. mixture control system
c. accelerating system
c.
- For what primary purpose is a turbine engine fuel control unit trimmed?
a. To obtain maximum thrust output when desired.
b. To properly position the power levers.
c. To adjust the idle RPM.
a.
- What is the relationship between the pressure existing within the throat of a venturi and the velocity of the air passing through the venturi?
a. There is no direct relationship between the pressure and the velocity.
b. The pressure is directly proportional to the velocity.
c. The pressure is inversely proportional to the velocity.
c.
- The fuel metering force of a conventional float-type carburetor in its normal operating range is the difference between the pressure acting on the discharge nozzle located within the venturi and the pressure
a. acting on the fuel in the float chamber
b. of the fuel as it enters the carburetor
c. of the air as it enters the venturi (impact pressure)
a.
- A major difference between the Teledyne-Continental and RSA (Precision Airmotive or Bendix) continuous flow fuel injection systems in fuel metering is that the
a. RSA system uses air pressure only as a metering force.
b. Continental system utilizes airflow as a metering force.
c. Continental system uses fuel pressure only as a metering force.
c.
- (1) The mixture used at rated power in air cooled reciprocating engines is richer than the mixture used through the normal cruising range.
(2) The mixture used at idle in air cooled reciprocating engines is richer than the mixture used at rated power.
Regarding the above statements,
a. only No. 1 is true
b. only No. 2 is true
c. both No. 1 and No. 2 are true
c.
- Generally, the practice when trimming an engine is to
a. turn all accessory bleed air off
b. turn all accessory bleed air on
c. make adjustments (as necessary) for all engines on the same aircraft with accessory bleed air settings the same - either on or off.
a.
- The device that controls the volume of the fuel/air mixture to the cylinders is called a
a. mixture control
b. metering jet
c. throttle valve
c.
- During engine operation, if carburetor heat is applied, it will
a. increase fuel/air ratio
b. increase engine RPM
c. decrease the air density to the carburetor
c.
- A nine-cylinder radial engine, using a multiple-point priming system with a central spider, will prime which cylinders?
a. One, two, three, eight, and nine
b. All cylinders
c. One, three, five, and seven
a.
- What effect does high atmospheric humidity have on the operation of a jet engine?
a. Decreases engine pressure ratio
b. Decreases compressor and turbine RPM
c. Has little or no effect
c.
- The throttle valve of float-type aircraft carburetors is located
a. ahead of the venturi and main discharge nozzle
b. after the main discharge nozzle and ahead of the venturi
c. between the venturi and the engine
c.
- On a float-type carburetor, the purpose of the economizer valve is to
a. provide extra fuel for sudden acceleration of the engine
b. maintain the leanest mixture possible during cruising best power
c. provide a richer mixture and cooling at maximum power output
c.
- In turbine engines that utilize a pressurization and dump valve, the dump portion of the valve
a. cuts off fuel flow to the engine fuel manifold and dumps the manifold fuel into the combustor to burn just before the engine shuts down
b. drains the engine manifold lines to prevent fuel boiling and subsequent deposits in the lines as a result of residual engine heat (at engine shutdown)
c. dumps extra fuel into the engine in order to provide for quick engine acceleration during rapid throttle advancement
b.
- If a float-type carburetor becomes flooded, the condition is most likely caused by
a. a leaking needle valve and seat assembly
b. the accelerating pump shaft being stuck
c. a clogged back-suction line
a.
- Which of the following is NOT an input parameter for a turbine engine fuel control unit?
a. Compressor inlet pressure
b. Compressor inlet temperature
c. Ambient humidity
c.
- An aircraft should be facing into the wind when trimming an engine. However, if the velocity of the wind blowing into the intake is excessive, it is likely to cause a
a. false low exhaust gas temperature reading
b. trim setting resulting in engine overspeed
c. false high compression and turbine discharge pressure, and a subsequent low trim
c.
- When troubleshooting an engine for too rich a mixture to allow the engine to idle, what would be a possible cause?
a. Economizer valve not operating correctly.
b. Mixture setting too rich.
c. Air leak in the intake manifold.
a.
- An aircraft engine equipped with a pressure-type carburetor is started with the
a. primer while the mixture control is positioned at IDLE CUTOFF
b. mixture control in the FULL-RICH position
c. primer while the mixture control is positioned at the FULL-LEAN position
a.
- The back-suction mixture control system operates by
a. varying the pressure within the venturi section
b. varying the pressure acting on the fuel in the float chamber
c. changing the effective cross-sectional area of the main metering orifice (jet)
b.
- On an engine equipped with a pressure-type carburetor, fuel supply in the idling range is ensured by the inclusion in the carburetor of
a. a spring in the unmetered fuel chamber to supplement the action of normal metering forces
b. an idle metering jet that bypasses the carburetor in the idle range
c. a separate boost venturi that is sensitive to the reduces airflow at start and idle speeds
a.
- What should be checked/changed to ensure the validity of a turbine engine performance check if an alternate fuel is to be used?
a. Fuel specific gravity setting
b. Maximum RPM adjustment
c. EPR gauge calibration
a.
- The device that controls the ratio of the fuel/air mixture to the cylinders is called a
a. throttle valve
b. mixture control
c. metering jet
b.
- Select the statement which is correct relating to a fuel level check of a float-type carburetor.
a. Use 5 pounds fuel pressure for the test if the carburetor is to be used in a gravity fuel feed system.
b. Block off the main and idle jets to prevent a continuous flow of fuel through the jets.
c. Do not measure the level at the edge of the float chamber.
c.
- If an aircraft engine is equipped with a carburetor that is not compensated for altitude and temperature variations, the fuel/air mixture will become
a. leaner as either the altitude or temperature increases
b. richer as the altitude increases and leaner as the temperature increases
c. richer as either the altitude or temperature increases
c.
- An aircraft engine continuous cylinder fuel injection system normally discharges fuel during which stroke(s)?
a. Intake
b. Intake and compression
c. All (continuously)
c.
- What carburetor component actually limits the desired maximum airflow to the engine at full throttle?
a. throttle valve
b. venturi
c. manifold intake
b.
- The desired engine idle speed and mixture setting
a. is adjusted with engine warmed up and operating
b. should give minimum RPM with maximum manifold pressure
c. is usually adjusted in the following sequence; speed first, the mixture
a.
- An indication that the optimum idle mixture has been obtained occurs when the mixture control is moved to IDLE CUTOFF and manifold pressure
a. decreases momentarily and RPM drops slightly before the engine ceases to fire
b. increases momentarily and RPM drops slightly before the engine ceases to fire
c. decreases and RPM increases momentarily before the engine ceases to fire
c.