PREPWARE - Turbine Engines (132) (tran edit)

6 (8113) - The *blending* of *blades and vanes* in a turbine engine

-is performed parallel to blade length, -w/smooth contours to min stress points.

36 (8143) - Which statements are true regarding aircraft engine propulsion? *1.* An engine driven *propeller* imparts a relatively *small amt* of *acceler* to a *large mass* of air. *2.* *Turbojet and turbofan* engines impart a relatively *large amt* of *acceler.* to a *smaller mass* of air. *3.* In modern turboprop engines, nearly 50% of the exhaust gas energy is extracted by turbines to drive the propeller and compressor with the rest providing exhaust thrust.

1 & 2

118 (8225) - Which of the following can *cause fan blade shingling* in a turbofan engine? 1. Engine overspeed. 2. Engine overtemperature. 3. Large, rapid throttle movements. 4. FOD.

1. Engine overspeed. & 4. FOD.

104 (8211) - What variables affect the inlet air density of a turbine engine? 1. _____________ 2. ______________ 3. _____________

1. Speed of the aircraft. 2. Altitude of the aircraft. 3. Ambient temperature.

104 (8211) - Which of the following *variables affect* the *inlet air density* of a turbine engine? *1. Speed of the aircraft.* 2. Compression ratio. 3. Turbine inlet temperature. *4. Altitude of the aircraft.* *5. Ambient temperature.* 6. Turbine and compressor efficiency.

1. Speed of the aircraft. 4. Altitude of the aircraft. 5. Ambient temperature.

105 (8212) - What factors affect the thermal efficiency of a turbine engine? 1. _____ 2. _____ 3. _____

1. TIT 2. Compression ratio. 5. Turbine and compressor efficiency.

105 (8212) - 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.

1. Turbine inlet temperature. 2. Compression ratio. 5. Turbine and compressor efficiency.

108 (8215) - Which *types of combustion sections* are used in aircraft turbine engines?

1. can 2. annular 3. can-annular.

83 (8190) - A *gas turbine engine* comprises which *three main sections*?

1. compressor 2. combustion 3. Turbine

40 (8147) - Where do *stress rupture crack*s usually *appear* on turbine blades?

Across the leading/trailing edge @ right angles to edge length.

Which statement is true regarding jet engines? A - At the lower engine speeds, thrust increases rapidly with small increases. B - At the higher engine speeds, thrust increases rapidly with small increases in RPM. C - The thrust delivered per pound of air is consumed is less at high altitude than at low altitude.

B - At the higher engine speeds, thrust increases rapidly with small increases in RPM.

38 (8145) - What is one *purpose* of the *stator blades* in the compressor* section of a turbine engine?

B- Control the direction of the airflow.

95 (8202) - A turbine engine *hot section* is particularly *susceptible* to *what* kind of *damage*?

B- Cracking.

101 (8208) - *Continued* and/or *excessive heat* and *centrifugal force on* turbine engine rotor *blades* is likely to *cause*

B- creep.

74 (8181) - SUBsonic air *pressure* _____ thru *convergent* nozzle?

B- decreases.

75 (8182) - SUPERsonic air *pressure* _____ thru *divergent* nozzle?

B- decreases.

76 (8183) - *Anti-icing* of jet engine air inlets *accomplished by*

B- engine bleed air ducted through the critical areas.

91 (8198) - The *procedure for removing* the accumulation of *dirt deposits* on compressor blades *is called*

B- field cleaning.

8 (8115) - In a gas turbine engine, *combustion occurs* at a *constant*

B- pressure.

86 (8193) - The *non-rotating axial-flow compressor airfoils* in an aircraft gas turbine engine, are called

B- stator vanes.

87 (8194) - *(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,*

Both #1 & #2 true

112 (8219) - What term is used to describe a *permanent and cumulative deformation* of the turbine *blades* of a turbojet engine?

C- Creep.

115 (8222) - In what *section* of a turbojet engine is the *jet nozzle located*?

C- Exhaust.

97 (8204) - *Severe rubbing* of turbine engine *compressor blades* will usually *cause*

C- galling.

37 (8144) - An *advantage* of the *axial-flow compressor* is its

C- high peak efficiency.

48 (8155) - *Reduced blade vibration* and *improved airflow* in gas turbines are brought about by

C- shrouded turbine rotor blades.

55 (8162) - Between each row of rotating blades in a turbine engine compressor, there is a *row of stationary blades* which act to *diffuse the air*. These stationary blades *are called*

C- stators.

50 (8157) - Jet engine turbine* blades removed* for detailed *inspection* must be *reinstalled in*

C- the same slot.

excessive heat + centrifugal force + rotor blades =

CREEP

41 (8148) - Which combustion chamber *type*, is the *case & liner* removed and installed *as one unit* during routine maintenance?

Can.

102 (8209) - If the *RPM* of an axial-flow compressor remains *constant*, the *angle of attack* of the rotor blades can be *changed by*

Changing airflow velocity

114 (8221) - At what *stage* in a turbine engine are *gas pressures the greatest*?

Compressor outlet.

69 (8176) - What is the *function* of the *inlet guide vane assembly* on an axial-flow compressor?

Directs air into the 1st stage rotor blades @ proper angle.

93 (8200) - What is the possible *cause* when a turbine *engine* indicates *no change in power* setting parameters, but *oil temp is high*?

Engine main bearing distress.

What can cause fan blade shingling in a turbofan engine? 1. _____________ 2. ____________

Engine overspeed. & FOD

106 (8213) - Why do some turbine engines have *more than one turbine wheel* attached to a single shaft?

Extracts more power from exhaust gases (than a single wheel can absorb)

78 (8185) - *Primary advantage* of an *axial-flow* compressor *over* a *centrifugal* compressor?

Greater pressure ratio

34 (8141) - How does a *dual axial-flow compressor* *improve the efficiency* of a turbojet engine?

Higher compression ratios can be obtained.

22 (8129) - *Two functional elements* in a *centrifugal compressor*?

Impeller and diffuser

84 (8191) - What *type of turbine blade* is most *commonly used* in aircraft *jet engines*?

Impulse-reaction.

10 (8117) - When *two spool* turboprop & turbojet engines *operate @ high altitudes*, the

LP rotor speed ↑ as compressor load ↓

17 (8124) - In the *dual axial-flow* or twin spool compressor system, the *first stage turbine drives* the

N2 compressor.

63 (8170) - In a dual axial-flow compressor, the *first stage turbine* drives

N2 compressor.

85 (8192) - *Primary factor* which *controls* the *pressure ratio* of an *axial-flow compressor*?

Number of stages in compressor.

43 (8150) - When the *leading edge* of a first-stage turbine *blade* is found to have *stress rupture cracks*, what should be suspected?

Overtemperature condition.

51 (8158) - An *advantage* of the *centrifugal-flow compressor* is its high

Pressure rise per stage

113 (8220) - What is the *purpose* of the *dump valve* used on aircraft gas turbine engines?

Quickly cut fuel off from nozzles & drain manifolds to prevent fuel boiling off from residual engine heat.

23 (8130) - What must be done *after the fuel control unit* has been *replaced* on an aircraft gas turbine engine?

Retrim the engine.

110 (8217) - What *type igniter plug* is used in the *low tension ignition system* of an aircraft turbofan engine?

Self-ionizing / shunted-gap

49 (8156) -* Which* turbine engine *compressor* offers the *greatest advantages* for both *starting flexibility* and *improved high-altitude performance*?

Split-spool, axial-flow.

65 (8172) - What is the *proper starting sequence* for a turbojet engine?

Starter, ignition, fuel.

20 (8127) - *Two basic elements* of the *turbine section*?

Stator & rotor.

58 (8165) - Turbine *blades* subjected to *excessive heat stress*, causes what *type of failure*?

Stress rupture.

81 (8188) - What is the *major function* of the *turbine assembly* in a turbojet engine?

Supplies the power to turn the compressor.

88 (8195) - *Air passing* thru the *combustion chamber* of a turbine engine*

Supports combustion & Cools engine

28 (8135) - *Who establishes* the recommended operating *time between overhauls* (TBO) of a turbine engine?

The engine manufacturer.

32 (8139) - *Who establishes* mandatory *replacement times* for critical components of turbine engines?

The engine manufacturer.

111 (8218) - What is meant by a *shrouded turbine*?

The turbine blades are shaped so their ends form a band or shroud.

64 (8171) - What should be done initially if a turbine *engine catches fire* when *starting*?

Turn off the fuel & continue engine rotation with the starter.

67 (8174) - What's used to *aid in stabilization of compressor airflow* during low thrust engine ops?

Variable guide vanes and/or compressor bleed valves.

70 (8177) - *Hot spots on the tail cone* of a turbine engine are possible *indicators of* a malfunctioning fuel nozzle or

a faulty combustion chamber

16 (8123) - When *starting* a turbine engine... a hot start..

a hot start is when EGT exceeds specified limits.

66 (8173) - A *weak fuel-to-air mixture* along with *normal airflow* thru a turbine engine *may result in*

a lean die-out.

77 (8184) - When *starting* a turbine engine, the *starter* should be *disengaged*

after engine reaches self-accelerating speed.

92 (8199) - What may be *used* to accomplish *internal inspection* of an assembled turbine engine?

borosope

116 (8223) - *(1)* Accumulation of contaminates in the compressor of a turbojet engine reduces aerodynamic efficiency of the blades. *(2)* Two common methods for removing dirt deposits from turbojet engine compressor blades are a fluid wash and an abrasive grit blast. *Regarding the above statements,*

both No 1 & No. 2 true.

8209.) Axial-flow compressor RPM = constant, change blade AOA by...

changing airflow velocity

99 (8206) - If a turbine engine is *unable to reach takeoff EPR* b4 *EGT limit is reached*, this is *an indication* that the

compressor is... contaminated or damaged.

1 (8108) - At what *point* in an *axial-flow* turbojet engine will the *highest gas pressures occur*?

compressor outlet.

42 (8149) - The *diffuser section* of a jet engine is *located* between

compressor section & burner section.

80 (8187) - What is a *double entry* centrifugal compressor?

compressor with vanes on both sides of the impeller.

71 (8178) - The *stator vanes* in an axial-flow compressor... converts...

convert velocity energy into pressure energy

109 (8216) - A *cool-off period prior to shutdown* of a turbine engine is *accomplished* in order *to*

cool turbine wheel b4 the case contracts around it.

82 (8189) - *Stator blades* in the compressor section of an axial-flow turbine engine

decrease air velocity & prevent swirling.

90 (8197) - The *compressor stators* in a gas turbine engine *act as diffusers to*

decrease gas flow velocity

2 (8109) - *function* of the *nozzle diaphragm* ?

direct gas flow to strike turbine blades @ desired angle

25 (8132) - A turbine engine *compressor* which contains *vanes on both* sides of the *impeller* is a

double entry centrifugal compressor.

15 (8122) - The *turbine* section of a jet engine... drives...

drives the compressor section.

14 (8121) - What is the *function* of the *stator vane assembly @ discharge end* of a typical axial-flow compressor?

eliminate turbulence by straightening airflow

12 (8119) - Where is the *highest gas pressure* in a turbojet engine?

entrance of burner section.

46 (8153) - The *recurrent ingestion* of *dust* or other fine airborne *particulates* into a turbine engine *can result in*

erosion damage to the compressor and turbine sections.

44 (8151) - *Turbine blades* are generally *more susceptible* to *ops damage* than compressor blades *because* of

exposure to high temperatures.

19 (8126) - When starting a turbine engine, a *hung start* is *indicated* if the engine

fails to reach idle RPM.

119 (8226) - *Compressor stall* is caused by

high AOA airflow thru 1st stages of compression.

107 (8214) - The *exhaust section*of a turbine engine is *designed to*

impart a high exit velocity to the exhaust gases.

35 (8142) - Name *Three* types of *turbine blades* are

impulse, reaction, impulse-reaction.

13 (8120) - An *exhaust cone* placed *aft of turbine* will cause *pressure* to

increase & velocity decrease.

89 (8196) - The *stators* in the *turbine section* do what?

increase gas flow velocity

39 (8146) - What is the *purpose* of the *diffuser section* in a turbine engine?

increase pressure & reduce velocity

11 (8118) - *Turbine nozzle diaphragms* (located on upstream sides of wheel) are *used* in the gas turbine engine *to*

increase velocity of heated gases flowing past this point.

18 (8125) - What's *used to mark* turbine engine *components* exposed to *high temps*?

layout dye

117 (8224) - *Hot spots* in the combustion section of a turbojet engine are *possible indicators of*

malfunctioning fuel nozzles.

24 (8131) - If, *during inspection* at engine overhaul, *ball or roller bearings* are found to *have magnetism* but otherwise have *no defects*, they

must be degaussed before use.

30 (8137) - *(1)* Welding and straightening of turbine engine rotating airfoils does not require special equipment. *(2)* Welding and straightening of turbine engine rotating airfoils is commonly recommended by the manufacturer. *Regarding the above statements*

neither No. 1 or No. 2 is true.

29 (8136) - 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,

neither No. 1 or No. 2 true. cold = inlet air duct, compressor, & diffuser Hot = combustion, turbine, & exhaust

103 (8210) - The *compression ratio* of an axial-flow compressor is a *function of* the

number of compressor stages.

94 (8201) - *Newton's 1st Law* of Motion, generally termed the Law of Inertia, *states*:

object in motion/rest stays in motion/rest, unless acted upon by a force

61 (8168) - *Hot section inspections* for many modern turbine engines *are required*

on a timed or cycle basis.

120 (8227) - *'Hot streaking'* in turbine engines is *caused by*

partially clogged fuel nozzle.

60 (8167) - *Compressor field cleaning* on turbine engines is *performed* primarily in order to

prevent -engine performance degradation, -increased fuel costs, & -damage/corrosion to gas path surfaces.

3 (8110) - What is the *profile* of a turbine engine *compressor blade*?

reduced blade tip thickness.

26 (8133) - *first engine instrument indication* of a *successful start* of a turbine engine?

rise in EGT

68 (8175) - In a turbine engine with a dual-spool compressor, the low speed compressor

seeks its own best operating speed.

54 (8161) - The *two types* of *centrifugal compressor impellers* are

single entry & double entry.

(8127.1) What *acts as a diffuser* & *converts velocity to pressure*?

stator

21 (8128) - The *function* of the *exhaust cone assembly* of a turbine engine is to

straighten & collect exhaust gases into a solid exhaust jet.

59 (8166) - In an axial-flow compressor, *one purpose of the stator vanes* at the discharge end of the compressor is to

straighten the airflow & eliminate turbulence.

5 (8112) - The abbreviation *Pt7* means?

total pressure @ station No. 7.

52 (8159) - The *highest heat-to-metal contact* in a jet engine is the

turbine inlet guide vanes.

79 (8186) - The *purpose* of a *bleed valve*, located in the *beginning stages* of the compressor,

vent some of the air overboard to prevent a compressor stall

*8201.1) Newton's 2nd Law of Motion "law of momentum" states:

when force acts on a mass, acceleration is produced (greater mass = greater force needed)

45 (8152) - What is the *ultimate limiting factor* of turbine engine operation?

(TIT) Turbine inlet temperature.

47 (8154) - What engine *variable* is the *most critical* during turbine engine operation?

(TIT) Turbine inlet temperature.

18 (8125) - During inspection, turbine engine *components exposed to high temp* may *only be marked with* 1_________ 2_________ 3__________

1. layout dye. 2. commercial felt tip marker. 3. chalk.

18 (8125) - During inspection, turbine engine *components exposed to high temp* may *only be marked with* 1. layout dye. 2. commercial felt tip marker. 3. wax or grease pencil. 4. chalk. 5. graphite lead pencil.

1. layout dye. 2. commercial felt tip marker. 4. chalk.

2 elements of 1.) axial flow 2.) centrifugal

1. rotor & stator 2. impeller & diffuser

Turbine engine *components exposed to high temperatures* generally *may NOT be marked* with 1. _________ 2. _________

1. wax or grease pencil 2. graphite lead pencil

56 (8163) - Standard sea level pressure is

29.92" Hg.

31 (8138) - 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.

3. wax or grease pencil 5. graphite lead pencil

92 (8199) - Which may be used to accomplish internal inspection of an assembled turbine engine? *1.* Infrared photography. *2.* Ultrasound. *3*. A borescope. *4*. Fluorescent penetrant and ultraviolet light.

3.) Boroscope

57 (8164) - Standard sea level temperature is

59°F.

9 (8116) - Which statement is true regarding jet engines? ↓↑ a) ↓ engine speeds, thrust ↑↑↑, rpm ↑ b) ↑ engine speeds, thrust ↑↑↑, rpm ↑ c) thrust/lb air consumed is less @ high alt than low alt

@ higher engine speeds, thrust ↑ rapidly with small ↑ in RPM. ↑ engine speeds, thrust ↑↑↑, rpm ↑

98 (8205) - What *influences the operation* of an *auto fuel control unit* on a turbojet engine?

A- Burner pressure.

7 (8114) - What turbine *engine section* provides for proper *mixing* of the *fuel and air*?

A- Combustion section.

33 (8140) - *Main bearing oil seals* used with turbine engines are usually what type(s)?

A- Labyrinth and/or carbon rubbing.

27 (8134) - Some engine manufacturers of twin spool gas turbine engines identify *turbine discharge pressure* in their maintenance manuals as

A- Pt7.

53 (8160) - Which *two elements* make up the *axial-flow compressor assembly*?

A- Rotor and stator.

96 (8203) - *Dirt particles* in the air, introduced into the compressor, *form a coating on what*?

A- Turbine blades.

72 (8179) - SUBsonic air *velocity* _______ thru *convergent* nozzle?

A- increases.

73 (8180) - SUPERsonic air *velocity* _____ thru *divergent* nozzle?

A- increases.

4 (8111) - The *fan rotational speed* of a *dual axial compressor* forward fan engine is the *same as* the

A- low-pressure compressor.

100 (8207) - The *Brayton cycle* is known as the *constant*

A- pressure cycle.

62 (8169) - A *purpose of the shrouds* on the turbine blades of an axial-flow engine is to

A- reduce vibration.