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fuel metering sys
FAA AMP
| Question | Answer |
|---|---|
| What could cause a lean mixture and high cylinder head temperature at sea level or low altitudes? | Automatic mixture control stuck in the extended position |
| (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, | Both are true |
| Select the statement which is correct relating to a fuel level check of a float-type carburetor. | Do not measure the level at the edge of the float chamber |
| What occurs when a back-suction type mixture control is placed in IDLE CUTOFF? | The float chamber will be vented to a negative pressure |
| The function of the altitude compensating, or aneroid valve used with the Teledyne-Continental fuel injection system on many turbocharged engines is to | Prevent an overly rich mixture during sudden acceleration |
| Which of the following best describes the function of an automatic mixture control (AMC)? | It compensates for change in the air density due to temperature and altitude |
| Reciprocating engine power will be decreased at all altitudes if the | Humidity is increased |
| The fuel level within the float chamber of a properly adjusted float-type carburetor will be | Slightly lower than the discharge nozzle outlet |
| The economizer system in a float-type carburetor | Increases the fuel/air ratio at high power settingsq |
| In a supervisory EEC system, any fault in the EEC that adversely affects engine operation | Causes an immediate reversion to control by the hydromechanical fuel control unit |
| An excessively lean fuel/air mixture may cause | An increase in cylinder head temperature |
| If the volume of air passing through a carburetor venturi is reduced, the pressure at the venturi throat will | Increase |
| What is the relationship between the pressure existing within the throat of a venturi and the velocity of the air passing through the venturi? | The pressure is inversely proportional to the velocity |
| Which method is commonly used to adjust the level of a float in a float-type carburetor? | Add or remove shims under the needle-valve seat |
| Which of the following is NOT an input parameter for a turbine engine fuel control unit? | Ambient humidity |
| The device that controls the ratio of the fuel/air mixture to the cylinders is called a | Mixture control |
| 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 |
| What will occur if the vapor vent float in a pressure carburetor loses its buoyancy? | The amount of fuel returning to the fuel tank from the carburetor will be increased |
| What is the possible cause of an engine running rich at full throttle if it is equipped with a float-type carburetor? | Clogged main air bleed |
| If a float-type carburetor becomes flooded, the condition is most likely caused by | a leaking needle Valve seat assembly |
| The active clearance control (ACC) portion of an EEC system aids turbine engine efficiency by | Ensuring turbine blade to engine case clearances are kept to a minimum by controlling case temperatures |
| What is the purpose of the carburetor accelerating system? | Temporarily enrich the mixture when the throttle is suddenly opened |
| When a new carburetor is installed on an engine, | And the engine is warmed up to normal temperatures, adjust the idle mixture, then the idle speed |
| The economizer system of a float-type carburetor performs which of the following functions? | It supplies and regulates the additional fuel required for all engine speeds above cruising |
| What effect does high atmospheric humidity have on the operation of a jet engine? | Has little or no effect |
| The device that controls the volume of the fuel/air mixture to the cylinders is called a | Throttle valve |
| When troubleshooting an engine that will not idle, what would be a probable cause? | Economized valve not operating correctly |
| Which of the following causes a single diaphragm accelerator pump to discharge fuel? | An increase in manifold pressure that occurs when the throttle valve is opened |
| One of the best ways to increase engine power and control detonation and preignition is to | Use water injection |
| The density of air is very important when mixing fuel and air to obtain a correct fuel-to-air ratio. Which of the following weighs the most? | 100 parts of dry air |
| Which statement is correct regarding a continuous-flow fuel injection system used on many reciprocating engines? | Fuel is injected at each cylinder intake port |
| When air passes through the venturi of a carburetor, what three changes occur? | Velocity increases, temperature decreases, and pressure decreases |
| Select the correct statement concerning the idle system of a conventional float-type carburetor. | The low pressure between the edges of the throttle valve and the throttle body pulls the fuel from the idle passage |
| Which of the following is NOT a function of the carburetor venturi? | Regulates the idle system |
| An electronic engine control (EEC) is a system that receives engine operating information and | Adjusts a standard hydromechanical fuel control unit to obtain the most effective engine operation |
| A mixture ratio of 11:1 normally refers to | I part of fuel to 11 parts of air |
| One of the things a metering orifice in a main air bleed helps to accomplish (at a given altitude) in a carburetor is | Better fuel vaporization and control of fuel discharge, specially at lower engine speeds |
| 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 | False high compression and turbine discharge pressure, and a subsequent low trim |
| How will the mixture of an engine be affected if the bellows of the automatic mixture control (AMC) in a pressure carburetor ruptures while the engine is operating at altitude? | It will become richer |
| The primary purpose of the air bleed openings used with continuous flow fuel injector nozzles is to | Aid in proper fuel vaporization |
| Under which of the following conditions will the trimming of a turbine engine be most accurate? | No wind and low moisture |
| What should be checked/changed to ensure the validity of a turbine engine performance check if an alternate fuel is to be used? | Fuel specific gravity setting |
| Refer to Figure 6.) Which curve most nearly represents an aircraft engine's fuel/air ratio throughout its operating range? | 2 |
| When trimming a turbine engine, the fuel control is adjusted to | Set idle RPM and maximum speed or EPR |
| During engine operation, if carburetor heat is applied, it will | Decrease the air density to the carburetor |
| The purpose of the back-suction mixture control in a float-type carburetor is to adjust the mixture by | Regulating the pressure on the fuel in the float chamber |
| A punctured float in a float-type carburetor will cause the fuel level to | Rise, and enrich the mixture |
| An indication that the optimum idle mixture has been obtained occurs when the mixture control is moved to IDLE CUTOFF and manifold pressure | Decreases and RPM increases momentarily before the engine ceases to fire |
| What component is used to ensure fuel delivery during periods of rapid engine acceleration? | Accelerating pump |
| A nine-cylinder radial engine, using a multiple-point priming system with a central spider, will prime which cylinders? | 1, 2, 3, 8, 9, |
| 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 opened |
| 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 |
| What factor is not used in the operation of an aircraft gas turbine engine fuel control unit? | Mixture control position |
| Where is the throttle valve located on a float-type carburetor? | After the main discharge nozzle and Venturi |
| An aircraft engine continuous cylinder fuel injection system normally discharges fuel during which stroke(s)? | All (continuously) |
| During the operation of an aircraft engine, the pressure drop in the carburetor venturi depends primarily upon the | Air velocity |
| During the operation of an aircraft engine, the pressure drop in the carburetor venturi depends primarily upon the | Ir aids in the emulsifying/vaporization of the fuel at idle speeds |
| What corrective action should be taken when a carburetor is found to be leaking fuel from the discharge nozzle? | Replace the needle valve and seat |
| Which of the following is least likely to occur during operation of an engine equipped with a direct cylinder fuel injection system? | Backfiring |
| 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 | Increase direction |
| The desired engine idle speed and mixture setting | Is adjusted with engine warmed up and operating |
| 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 |
| What carburetor component measures the amount of air delivered to the engine? | Venturi |
| If an aircraft engine is equipped with a carburetor that is not compensated for altitude and temperature variations, the fuel/air mixture will become | Rich we as either the altitude or temperature increases. |
| During idle mixture adjustments, which of the following is normally observed to determine when the correct mixture has been achieved? | Changes in RPM or manifold pressure |
| In turbine engines that utilize a pressurization and dump valve, the dump portion of the valve | Drains the engine manifold lines to prevent fuel boiling and subsequent deposits in the lines as a result of residual engine heat (at e nine shutdown) |
| On a carburetor without an automatic mixture control as you ascend to altitude, the mixture will | Be enriched |
| An aircraft carburetor is equipped with a mixture control in order to prevent the mixture from becoming too | Rich at high altitudes |
| Float-type carburetors which are equipped with economizers are normally set for | Their leanest practical mixture delivery at cruising speeds and enriched by means of the economizer system at higher power settings |
| One purpose of an air bleed in a float-type carburetor is to | Decrease fuel density and destroy surface tension. |
| 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 |
| What method is ordinarily used to make idle speed adjustments on a float-type carburetor? | An adjustable throttle stop or linkage |
| A carburetor is prevented from leaning out during quick acceleration by the | Accelerating system |
| Which of the following best describes the function of an altitude mixture control? | Regulates the richness of the fuel/air charge entering the engine |
| The use of less than normal throttle opening during starting will cause | A rich mixture |
| 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 | An increase of 10 to 50 RPM before decreasing |
| The throttle valve of float-type aircraft carburetors is located | Between the Venturi and the engine |
| An aircraft engine equipped with a pressure-type carburetor is started with the | Primer while the mixture control is positioned at IDLE CUTOFF |
| If fuel is found running from the carburetor with the engine not running, the likely cause is that the | Float needle valve is not seated properly |
| Prior to performing engine trimming, you should | Obtain a true temperature reading comparable to that of the air that enters the engine |
| The back-suction mixture control system operates by | Varying the pressure acting on the fuel in the float chamber |
| If the idling jet becomes clogged in a float-type carburetor, the | Engine will not idle |
| Detonation occurs when the fuel/air mixture | Burns too fast |
| Why must a float-type carburetor supply a rich mixture during idle? | Because at idling speeds the engine may not have enough airflow around the cylinders to provide proper cooling |
| Fuel is discharged for idling speeds on a float-type carburetor | From the idle discharge nozzle |
| A full-authority electronic engine control (EEC) is a system that receives all the necessary data for engine operation and | Develops the commands to various actuators to control engine parameters |
| On a float-type carburetor, the purpose of the economizer valve is to | Provide a richer mixture and cooling at maximum power output |
| At what engine speed does the main metering jet actually function as a metering jet in a float-type carburetor? | All RPMs above idle range |
| Under which of the following conditions would an engine run lean even though there is a normal amount of fuel present? | Incomplete fuel vaporization |
| If an engine is equipped with a float-type carburetor and the engine runs excessively rich at full throttle, a possible cause of the trouble is a clogged | Main air bleed |
| What is the relationship between the accelerating pump and the enrichment valve in a pressure injection carburetor? | No relationship since they operate independently |
| For what primary purpose is a turbine engine fuel control unit trimmed? | To obtain maximum thrust output when desired |
| The metered fuel pressure (chamber C) in an injection-type carburetor | Is held constant throughout the entire engine operating range |
| If the main air bleed of a float-type carburetor becomes clogged, the engine will run | Rich at rated power |
| Generally, the practice when trimming an engine is to | Turn all accessory bleed air off |
| Which type of fuel control is used on most of today's turbine engines? | Hydromechanical or electronic |
| What carburetor component limits the maximum airflow into the engine at full throttle? | Venturi |
| A major difference between the Teledyne-Continental and RSA (Precision Airmotive or Bendix) continuous flow fuel injection systems in fuel metering is that the | Continental system uses fuel pressure only as a metering force |
Created by:
cordon.gabriel
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