Turbine Engines Flashcards
- Turbine engine components exposed to high temperatures generally may NOT be marked with
(1) layout dye
(2) commercial felt tip marker
(3) wax or grease pencil
(4) chalk
(5) graphite lead pencil
a. 1,2, and 3
b. 3 and 5
c. 4 and 5
b.
- Jet engine turbine blades removed for detailed inspection must be reinstalled in
a. a specified slot 1800 away.
b. a specified slot 900 away in the direction of rotation
c. the same slot
c.
- The blending of blades and vanes in a turbine engine
a. is usually accomplished only at engine overhaul
b. should be performed parallel to the length of the blade using smooth contours to minimize stress points
c. may sometimes be accomplished with the engine installed, ordinarily using power tools
b.
- One function of the nozzle diaphragm in a turbine engine is to
a. Decrease the velocity of exhaust gases
b. Center the fuel spray in the combustion chamber
c. Direct the flow of gases to strike the turbine blades at the desired angle.
c.
- Some high-volume turboprop and turbojet engines are equipped with two-spool or split compressors. When these engines are operated at high altitudes, the
a. low-pressure rotor will increase in speed as the compressor load decreases in the lower density air.
b. throttle must be retarded to prevent overspeeding of the high-pressure rotor due to the lower density air.
c. low-pressure rotor will decrease in speed as the compressor load decreases in the lower density air.
a.
- A gas turbine engine comprises which three main sections?
a. Compressor, diffuser, and stator
b. Turbine, combustion, and stator
c. Turbine, compressor, and combustion
c.
- An exhaust cone placed aft of the turbine in a jet engine will cause the pressure in the first part of the exhaust duct to
a. increase and the velocity to decrease
b. increase and the velocity to increase
c. decrease and the velocity to increase
a.
- The compression ratio of an axial-flow compressor is a function of the
a. number of compressor stages
b. rotor diameter
c. air inlet velocity
a.
- If a turbine engine is unable to reach takeoff EPR before its EGT limit is reached, this is an indication that the
a. fuel control must be replaced
b. EGT controller is out of adjustment
c. compressor may be contaminated or damaged
c.
- Which turbine engine compressor offers the greatest advantages for both starting flexibility and improved high-altitude performance?
a. Dual-stage, centrifugal-flow
b. Split-spool, axial-flow
c. Single-spool, axial-flow
b.
- Who establishes the recommended operating time between overhauls (TBO) of a turbine engine used in general aviation?
a. The engine manufacturer
b. The operator (utilizing manufacturer data and trend analysis) working in conjunction with the FAA
c. The FAA
a.
- Which statements are true regarding aircraft engine propulsion?
(1) An engine driven propeller imparts a relatively small amount of acceleration to a large mass of air.
(2) Turbojet and turbofan engines impart a relatively large amount of acceleration to a smaller mass of air.
(3) In modern turboprop engines, nearly 50 percent of the exhaust gas energy is extracted by turbines to drive the propeller and compressor with the rest providing exhaust thrust.
a. 1,2,3
b. 1,2
c. 1,3
b.
- Continued and/or excessive heat and centrifugal force on turbine engine rotor blades is likely to cause
a. profile
b. creep
c. galling
b.
- The procedure of removing the accumulation of dirt deposits on compressor blades is called
a. the soak method
b. field cleaning
c. the purging process
b.
- The stators in the turbine section of a gas turbine engine
a. increase the velocity of the gas flow
b. decrease the velocity of the gas flow
c. increase the pressure of the gas flow
a.
- What is the first engine instrument indication of a successful start of a turbine engine?
a. A rise in the engine fuel flow
b. A rise in oil pressure
c. A rise in the exhaust gas temperature
c.
- In what section of a turbojet engine is the jet nozzle located?
a. Combustion
b. Turbine
c. Exhaust
c.
- The recurrent ingestion of dust or other fine airborne particulates into a turbine engine can result in
a. foreign object damage to the compressor section
b. the need for less frequent abrasive grit cleaning of the engine
c. erosion damage to the compressor and turbine sections
c.
- What turbine engine section provides for proper mixing of the fuel and air?
a. Combustion section
b. Compressor section
c. Diffuser section
a.
- Which two elements make up the axial-flow compressor assembly?
a. Rotor and stator
b. Compressor and manifold
c. Stator and diffuser
a.
- Three types of turbine blades are
a. reaction, converging, and diverging
b. impulse, reaction, and impulse-reaction
c. impulse, vector, and impulse-vector
b.
- The purpose of a bleed valve, located in the beginning stages of the compressor, in an aircraft gas turbine engine is to
a. vent some of the air overboard to prevent a compressor stall
b. control excessively high RPM to prevent a compressor stall
c. vent high ram air pressure overboard to prevent a compressor stall
a.
- An advantage of the axial-flow compressor is
a. low starting power requirements
b. low weight
c. high peak efficiency
c.
- Who establishes mandatory replacement times for critical components of turbine engines?
a. The FAA
b. The operator working in conjunction with the FAA
c. The engine manufacturer
c.
- What type igniter plug is used in the low tension ignition system of an aircraft turbofan engine?
a. Low voltage, high amperage glow plug
b. Self-ionizing or shunted-gap type plug
c. Recessed surface gap plug
b.
- The velocity of subsonic air as it flows through a convergent nozzle
a. increases
b. decreases
c. remains constant
a.
- When starting a turbine engine,
a. a hot start is indicated if the exhaust gas temperature exceeds specified limits.
b. an excessively lean mixture is likely to cause a hot start.
c. release the starter switch as soon as indication of light-off occurs.
a.
- Hot section inspections for many modern turbine engines are required
a. only at engine overhaul
b. only when an overtemperature or overspeed has occurred
c. on a time or cycle basis
c.
- What are the two functional elements in a centrifugal compressor?
a. Turbine and compressor
b. Bucket and expander
c. Impeller and diffuser
c.
- Hot spots in the combustion section of a turbojet engine are possible indicators of
a. faulty igniter plugs
b. dirty compressor blades
c. malfunctioning fuel nozzles
c.
- How does a dual axial-flow compressor improve the efficiency of a turbojet engine?
a. More turbine wheels can be used.
b. Higher compression ratios can be obtained.
c. The velocity of the air entering the combustion chamber is increased.
b.
- (1) In a turbine engine axial-flow compressor, each consecutive pair of rotor and stator blades constitutes a pressure stage.
(2) In a turbine engine axial-flow compressor, the number of rows of stages is determined by the amount of air and total pressure rise required.
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.
- The basic gas turbine engine is divided into two main sections: the cold section and the hot section.
(1) The cold section includes the engine inlet, compressor, and turbine sections.
(2) The hot section includes the combustor, diffuser, and exhaust sections.
Regarding the above statements,
a. only No. 1 is true
b. only No. 2 is true
c. neither No. 1 nor No. 2 is true
c.
- If the RPM of an axial-flow compressor remains constant, the angle of attack of the rotor blades can be changed by
a. changing the velocity of the airflow
b. changing the compressor diameter
c. increasing the pressure ratio
a.
- Which of the following factors affect the thermal efficiency of a turbine engine?
(1) Turbine inlet temperature
(2) Compression ratio
(3) Ambient temperature
(4) Speed of the aircraft
(5) Turbine and compressor efficiency
(6) Altitude of the aircraft
a. 3, 4, 6
b. 1, 2, 5
c. 1, 2, 6
b.
- The velocity of supersonic air as it flows through a divergent nozzle
a. increases
b. decreases
c. is inversely proportional to the temperature
a.
- Where do stress rupture cracks usually appear on turbine blades?
a. Across the blade root, parallel to the fir tree
b. Along the leading edge, parallel to the edge
c. Across the leading or trailing edge at a right angle to the edge length
c.
- In a gas turbine engine, combustion occurs at a constant
a. volume
b. pressure
c. density
b.
- What is meant by a double entry centrifugal compressor?
a. A compressor that has two intakes.
b. A two-stage compressor independently connected to the main shaft.
c. A compressor with vanes on both sides of the impeller.
c.
- The pressure of supersonic air as it flows through a divergent nozzle
a. increases
b. decreases
c. is inversely proportional to the temperature
b.
- What is the proper starting sequence for a turbojet engine?
a. Ignition, starter, fuel
b. Starter, ignition, fuel
c. Starter, fuel, ignition
b.
- Which of the following types of combustion sections are used in aircraft turbine engines?
a. Annular, variable, and cascade vane
b. Can, multiple-can, and variable
c. Multiple-can, annular, and can-annular
c.
- Generally, when starting a turbine engine, the starter should be disengaged
a. after the engine has reached self-accelerating speed
b. only after the engine has reached full idle RPM
c. when the ignition and fuel system are activated
a.
- In which type of turbine engine combustion chamber is the case and liner removed and installed as one unit during routine maintenance?
a. Can
b. Can annular
c. Annular
a.
- What is the function of the stator vane assembly at the discharge end of a typical axial-flow compressor?
a. To straighten airflow to eliminate turbulence
b. To direct the flow of gases into the combustion chambers
c. To increase air swirling motion into the combustion chambers
a.
- Some engine manufacturers of twin spool gas turbine engines identify turbine discharge pressure in their maintenance manuals as
a. Pt7
b. Pt2
c. Tt7
a.
- Compressor field cleaning on turbine engines is performed primarily in order to
a. prevent engine oil contamination and subsequent engine bearing wear or damage
b. facilitate flight line inspection of engine inlet and compressor areas for defects or FOD.
c. prevent engine performance degradation, increased fuel costs, and damage or corrosion to gas path surfaces.
c.