FAA Engine Fuel and Fuel Metering Systems (5)

What are the positions of the pressurization valve and the dump valve in a jet engine fuel system when the engine is shut down?. Pressurization valve closed, dump valve open. Pressurization valve open, dump valve open. Pressurization valve closed, dump valve closed.

Fuel is discharged for idling speeds on a float-type carburetor. from the idle discharge nozzle. in the venturi. through the idle discharge air bleed.

An indication that the optimum idle mixture has been obtained occurs when the mixture control is moved to IDLE CUTOFF and manifold pressure. decreases momentarily and RPM drops slightly before the engine ceases to fire. increases momentarily and RPM drops slightly before the engine ceases to fire. decreases and RPM increases momentarily before the engine ceases to fire.

The fuel pump relief valve directs excess fuel to the. fuel tank return line. inlet side of the fuel pump. inlet side of the fuel strainer.

To determine the float level in a float-type carburetor, a measurement is usually made from the top of the fuel in the float chamber to the. parting surface of the carburetor. top of the float. centerline of the main discharge nozzle.

Under which of the following conditions would an engine run lean even though there is a normal amount of fuel present?. The use of too high an octane rating fuel. Incomplete fuel vaporization. The carburetor air heater valve in the HOT position.

Idle cutoff is accomplished on a carburetor equipped with a back-suction mixture control by. introducing low pressure (intake manifold) air into the float chamber. turning the fuel selector valve to OFF. the positive closing of a needle and seat.

What could cause a lean mixture and high cylinder head temperature at sea level or low altitudes?. Mixture control valve fully closed. Defective accelerating system. Automatic mixture control stuck in the extended position.

In a supervisory EEC system, any fault in the EEC that adversely affects engine operation. causes redundant or backup units to take over and continue normal operation. usually degrades performance to the extent that continued operation can cause damage to the engine. causes an immediate reversion to control by the hydromechanical fuel control unit.

Which of the following is NOT a function of the carburetor venturi?. Proportions the fuel/air mixture. Regulates the idle system. Limits the airflow at full throttle.

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 spring in the unmetered fuel chamber to supplement the action of normal metering forces. an idle metering jet that bypasses the carburetor in the idle range. a separate boost venturi that is sensitive to the reduced airflow at start and idle speeds.

What is the purpose of the flow divider in a turbine engine duplex fuel nozzle?. Allows an alternate flow of fuel if the primary flow clogs or is restricted. Creates the primary and secondary fuel supplies. Provides a flow path for bleed ail which aids in the atomization of fuel.

The device that controls the volume of the air-fuel mixture to the cylinders is called a. mixture control. metering jet. throttle valve.

An excessively lean air-fuel mixture may cause. an increase in cylinder head temperature. high oil pressure. backfiring through the exhaust.

Which of the following causes a single diaphragm accelerator pump to discharge fuel?. An increase in venturi suction when the throttle valve is open. An increase in manifold pressure that occurs when the throttle valve is opened. A decrease in manifold pressure that occurs when the throttle valve is opened.

Which type of pump is commonly used as a fuel pump on reciprocating engines?. Gear. Impeller. Vane.

What is a characteristic of a centrifugal-type fuel boost pump?. It separates air and vapor from the fuel. It has positive displacement. It requires a relief valve.

What is a function of the idling air bleed in a float-type carburetor?. It provides a means for adjusting the mixture at idle speeds. it vaporizes the fuel at idling speeds. it aids in emulsifying/vaporizing the fuel at idle speeds.

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. acting on the fuel in the float chamber. of the fuel as it enters the carburetor. of the air as it enters the venturi (impact pressure).

How often should float carburetors be overhauled?. At engine overhaul. Annually. At engine change.

What are the principal advantages of the duplex fuel nozzle used in many turbine engines?. Restricts the amount of fuel flow to a level where more efficient and complete burning of the fuel is achieved. Provides better atomization and uniform flow pattern. Allows a wider range of fuels and filters to be used.

A fuel pressure relief valve is required on. engine-driven diaphragm-type fuel pumps. engine-driven vane-type fuel pumps. centrifugal fuel boost pumps.

An aircraft engine equipped with a pressure-type carburetor is started with the. primer while the mixture control is positioned at IDLE CUTOFF. mixture control in the FULL-RICH position. primer while the mixture control is positioned at the FULL-LEAN position.

Which of the following statements concerning a centrifugal-type fuel boost pump located in a fuel supply tank is NOT true?. Air and fuel vapors do not pass through a centrifugal-type pump. Fuel can be drawn through the impeller section of the pump when it is not in operation. The centrifugal-type pump is classified as a positive displacement pump.