Jet Engine

1

1. Blade is an angle formed by a line perpendicular to the propeller shaft and line formed by the

(a) Relative wind

(b) Apparent wind

(c) Chord of the blade

(d) Blade face

2. Thrust produced by a rotating propeller is a result of

(a) Propeller slippage

(b) An area of low pressure behind the propeller

(c) An area of decreased pressure immediately in front of the pressure blades

(d) The angle of relative wind and rotational velocity wind and rotational velocity of the propeller

3. Propeller blade station number increase from

(a) Huh to tip

(b) Tip to hule

(c) Leading edge to aft edge

(d) Aft edge of leading edge

4. It should have high specific gravity

(a) Low pan point

5. Velocity index should be high. High freezing point at a cold atm the water contents in the fuel in having tendency to form in a ice crystal

6. It should be filtered to jet engine

(a) It should have low carbon content after burning the fuel

7. In twin spool engine, with constant N2, compressor inlet temperature is decreasing then

(a) N2 changes

(b) Fuel flow increases

(c) N1 decreases

(d) The ratio N1 is maintained constant

N2

8. The thrust developed by high bypass ratio engine is

(a) Indicated by EGT

(b) Indicated by N2

(c) Proportional fan speed

(d) Not affected by ambient conditions

9. Perceived noise decibel (PNDB) level is low in case of

(a) Pure jets without noise suppressor

(b) Straight jet with noise suppressor

(c) Low by pass jets

(d) High by pass jets with acoustic panel

10. Ignitor plug spark is due to

(a) High frequency

(b) High input current

(c) Discharge (storage) capacitor

(d) DC voltage

11. In a hot tank oil system

(a) Oil cooler is not provided

(b) Oil is stored in a separate tank

(c) Oil is at high temp in the tank

(d) De-aerator effect is very slow

12. If jet velocity and mass flow is constant for a jet engine then thrust

(a) Is maximum when aircraft speed is minimum

(b) Is maximum when aircraft speed is maximum

(c) Is more when jet velocity and inlet velocity are equal

(d) Is always constant

13. Water injection systems are provides for the jet engine for the thrust augmentation the thrust augmentation for water injection can be caused and by two methods.

(a) By adding or injecting water at the compressor inlet

(b) By adding or injecting water at the differ section

Fig shown that a water tank made up of aluminum or sheet metal allows the water flow a regulating

It then panes to the pressure regulating V/o of the diffuse and compressor inlet thought which water injection in done by providing two manifolds at the diffuse and compressor manifold.

A water heater is provided for the water to not formed ice in cold atm or cold weather condition

A drain a/v provided to drain full water tank after are it is generally use of after getting sufficient thrust by water injection

Water injection system used when aircraft an going to take off

14. In a compressor space between surge line and working lines called

(a) Safety margin on surge margin

(b) Stable zone unstable zone

(c) Unstable zone

(d) Stagger zone

15. Hottest zone in turbine engine is

(a) Compressor outlet

(b) Turbine

(c) 1st stage NGV

(d) Exhaust nozzle

16. In a high by pass engine NGVs are eliminated

(a) To reduced noise

(b) To reduce weight

(c) To increase efficiency

(d) To satisfy 1 and 2 above

For maximum thrust

The thrust augmentation is achieved a the compressor inlet by injecting water at the compressor inlet which increases mass airflow and their by thrust

Thrust augmentation is achieved a the diffuser section by injecting water at the diffuser section and which als the diffuser section and decreases the temperature of the diffuser section which gives high deme man airflow high affect to maximum

17. Brayton cycle is

(a) Constant temperature cycle

(b) Constant volume cycle

(c) Constant pressure and constant temperature cycle

18. NGVs of turbine are usually

(a) Hollow

(b) Solid

(c) Air cooled

(d) As per (1) & (2) above

19. Most common defects in combustion chamber is

(a) Crack and burning

(b) Scoring

(c) Pitting

(d) Blistering

20. Jet engine ignition system.

Jet engine ignition system is a high intensity and dual capacitor discharge type are used

The two system are used for the ignition system

(a) Low voltage A.C or D.C type ignition system

(b) High voltage capacitor discharge type ignition system

21. High voltage capacitor discharge type ignition system

FIGURE SHOWN HIGH VOLTAGE CAPACITOR DISHCARGE TYPE CUT (A.G)

A 115 A.C is provided bu E.S.I. but to the primary coil of the transformer A to reduce the noise level a filter cut is provided at the primary

After paning 115V at the primary a seen way coil induces a voltage of about 2000V approximately which paner through solid rectifier A through resistance to the dual capacitor or storage capacitor which store the electrically charger

In the next cycle a 20000 is paned through rectifier B this resistance

22. Combustion chamber used in a modern jet engines are

(a) Can annular type

(b) Annular type

(c) Can type

(d) As stated in 1 and 2

23. Exhaust nozzle is

(a) No necessary for jet engines

(b) Made up of titanium alloy

(c) Made up of aluminum alloy

(d) A must for jet engine

24. Internal energy of a perfect gas is

(a) A function of temperature only

(b) A function of pressure only

(c) Always constant

(d) A function of temperature and pressure

25. The turbo jet engines

(a) Can be used in thermal power stations as prime stations as primer movers

(b) Are more efficient at lower altitudes

(c) Work on Newtons third law of motion

(d) (2) and (3) above are correct

26. Compression process in axial compressor is

(a) Isothermal

(b) Adiabatic

(c) Isobaric

(d) Isometric

27. Compressor pressure ratio of an engine compressor depends upon

(a) Ambient pressure

(b) Ambient temperature and ambient pressure

(c) Speed and ambient pressure

(d) Speed mass airflow and ambient temperature

The energy stored in a dual capacitor and storage charger at a fule charge level and then tenses the tube this caused charger when fully developed it induces in the primary winding of the transformer (TRIGGER), which is of up to app 2000 V

This induces a appx of 20,000V to the secondary of the tram former winding and which gives high intensity current flow thr ignite plug which gives spark

A bleeder resistance are provided for troiger capacitor to give protection for excess voltage

Two igniter plug are used for capacitor discharge type cht for alternate operations

28. The fuel nozzles used in modern gas turbine engines

(a) Are always of dual type

(b) Are identical for engine with same power rating

(c) Are welded to the combustion chamber

(d) Is the last component in the fuel system

29. Anti icing system used on jet aircrafts

(a) Is fully automatic

(b) Is to be used only to melt the ice formed

(c) Never makes use of electrical heaters

(d) Need not be used thought the flight

30. How many igniters are usually used on a turbine engine having nine burner cans?

(a) One

(b) Two

(c) Three

(d) Nine

31. The material used for jet engine is following main fine types

(a) Titanium

(b) Aluminum or Aluminum alloy

(c) Nickel bare alloy

(d) Nickel chrome alloy

(e) Steel or stainless steel

Titanium are high resistant to 1000 & corrosion and are used for fan blades and sometime for compressor vanes

Aluminum or aluminum alloy are used for jet engine for its light weight characteristics it is high resistant to corrosion heat

Nickel- chrome alloys re used fore turbine blades, which stands for high temperature

Steel or stainless steel alloy are used for rota vane or staten vane in an axial flow type jet

32. In an axial flow turbine engine, compressor bled air is sometimes used to aid in the cooling of

(a) Oil

(b) IGV

(c) Fuel cooler

(d) Turbine

33. Which of the following turbine fuel filters has the greatest filtering action?

(a) Micron

(b) Wire mesh

(c) Wafer screen

(d) Stacked charcoal

34. For starting a turbine engine

(a) D.C motor is never used

(b) Very very low cranking speeds are required

(c) Ignition is necessary

(d) Statements 2 and 3 are correct

35. Mechanical integrity of the turbine as well as engine operating conditions of the engine can be checked by

(a) Engine oil pressure

(b) Exhaust gas temperature

(c) Engine oil temperature

(d) Engine pressure ratio

36. Which parameter will determine engine power?

(a) EGT and vibration meter

(b) RPM and oil pressure

(c) RPM and fuel pressure

(d) EPR OR RPM

37. Mark the correct statement

(a) Thrust reverse reduces landing roll

(b) Oil pressure for jet engine is always regulated

(c) VSV are not provided on modern jet engine

(d) By providing fire wall in the engine cowl compartment engine fire detection element can be eliminated

JET ENGINE JUNE 2002

1. EGT measuring thermocouples are connected in

(a) Series

(b) Parallel

(c) Series parallel

2. Angle of attack of a propeller is

(a) Angle between chord line and plane of rotations

(b) Angle between chord line and relative wind direction

(c) Angle between chord line and longitudinal axis the aircraft


(a) Geometric pitch is the distance traveled by propeller in one rotations

(b) Effective pitch is the actual distance traveled by the propeller in on rotations

(c) Slip is the difference between geometric pitch and effective pitch

(d) All of the above

4. Mark the correct statement regarding propeller tracking

(a) Propeller tracking is determining tip position relative to others propeller

(b) Static balancing of propeller

(c) Dynamic balancing of propeller



(a) In alpha range blade angle is controlled by governor

6. Compressor blades are attached with disc

(a) Dove tail

(b) Fir tree with various locking

(c) -------------------------

(d) as above (a) & (b)

7. Reduced cooling air requirements by 50 percent and decreased wt. By 20% is in which system

(a) Airflim cooling

(b) Transpiration cooling

(c) Impergement cooling

(d) Finwall

8. Mark correct statement regarding gas turbine igniter

(a) Gap is more engine to reciprocating because operating provision

(b) As (a) and less fouling problem

(c) As (b) and high energy

(d) As (c) and

Condition lever (propeller lever) controls free power turbine (Nf)

Power lever (Throttle) controls - FCU & has generator turbine (N8)

If instruction indicating high / rise then compressor combination

If instruction indicating low / decrease then turbine de effectors

9. Shrouding of turbine blades

(a) Reduces tip loss

(b) As (a) prevent excessive vibration

(c) As (b) and prevent twisting

(d) As (c) and operate cool as extra mass in tip at reduced speed

10. Mark correct statement

(a) Thrust reverse is used in the fan discharge

(b) 50% reverse thrust provided 35 to 50%

(c) Core engine exhaust is used for forward thrust

(d) All the above

11. Wet thrust rating is

(a) Water injection is on

(b) Cooling period of engine

(c) Water injection off

(d) Diffuser

12. Water is injected in compressor inlet and difficult then

(a) Surge line shifts down

(b) Surge line shifts away

13. Speed droop is common to all mechanical governors to reduce these problems

(a) Use a weaker spring

(b) Make metering valve narrow radially

(c) Decrease pressure difference across metering valve



(a) Paper cartage type filter used in low preside

(b) As 1 and screen disc type filter used I hi pr side

(c) As 2 and


15. For lubrication

(a) Hi viscosity index oil lis required

(b) Hi acidity oil is used

(c) Hi pour point oil is used


16. Mark the correct and statement

(a) Scavenger pump is centrifugal type of the larger capacity

(b) Pr pump is centrifugal type

(c) Scavenger pump capacity is smaller than Pr. Pump

(d) Both pump are gear type

17. Pressure relief valve pr I equipped with centrifugal boast arrangement

(a) Boost pump pressure

(b) Main pump pr

(c) Filter pr


18. In starter generator

(a) Two field winding are used

(b) One common armature is used

(c) Starter is used for starting of generator for electrical power


19. In gas turbine engine

(a) Starter is disconnected as soon as light off

(b) Starter is on to give specified speed to engine

20. In performance monitor ring all parameter are in increasing order then it shows failure

(a) Turbine

(b) Compressor

(c) Combustion

(d) In let guidvave

21. During starting fire, fire extinguisher is discharge

(a) Engine is cleaned

(b) Engine replaced and sent to shape

22. Blending is done to

(a) Recountering the blade

23. For the maintenance purpose engine is divide in the two section, in hot section

(a) Turbine combustion exhaust nozzle

(b) Turbine, diffuser, exhaust nozzle

(c) HP compressor, combustion, exhaust nozzle

(d) HP compressor, combustion, turbine

24. FCU senses

(a) Rpm

(b) As I and CDP

(c) As 2 and EDP

(d) AS 3 AND cip

25. In helicopter which engine is used

(a) Turbo shaft

(b) Turbo fan

(c) Free power turbine (N1)

(d) Above 1 & 3

26. Advantage of centrifugal compressor

(a) Hi pr ratio per stage

27. In convergent nozzle used in supersonic speed

(a) Pr. Increased volume decreased

(b) Velocity increased

28. Bleeding check

(a) Bleed valve closed

(b) Bleed valve open

(c) Variable stator vane close

29. TSFC is

(a) Directly proportional to compression ration

(b) Indirectly


(a) Thrust due to pr fall is more than thrust increase due to temperature fall


(a) Most compression engines using annular combustion chamber

(b) Can annular is best efficient

32. Which one is fuel flow rate indicator without motor

(a) Vane type

(b) Impeller turbine type


(a) Red radial line is maximum permissible range

34. In two wire thermal switch fire detecting

(a) Open circuit will give indication

35. In modern vibration indication system

(a) It consists of pick up, signal conditional indicator

(b) Later piezoelectric acceleration

(c) Later electromechanical velocity

36. Rhumble occurs

(a) P & D valve malfunction

(b) FCU malfunction

(c) Fuel nozzle partially clogged

(d) All of above

37. Which component is not mounted on engine

(a) Boost pump

(b) Pressure pump

(c) P & D valve

38. Mark correct statement regarding oil pressure indicating system

(a) Thermocouple

(b) Autosyn

(c) Temperature buld

39. Anti icing valve is used for

(a) To avoid ice formation

(b) -----

(c) ----

(d) ---

40. In fuel metering valve

(a) Orifice area is varied

(b) A constant fuel pressure across valve

(c) 1 2 2 are correct

(d) -------

41. Which is fire-extinguishing agent

(a) Freon

(b) Bromochloro difloromethane

(c) Bromo fluoromethane


42. Triming is carried out when

(a) FCU is changed

(b) Specific gravity of fuel

(c) For performance recovery


SUBJECTIVE QUESTIONS1. a. Explain active clearance control in the modern turbo fan engine

b. Method of turbine blade cooling with fig

c. Field cleaning

2. a. Explain the breather system with diagram

b. Show thrust Vs air speed of turboprop turbofan and turbojet engine

3. a. In axial flow compressor why gas flow path is made convergent explain

b. What is the advantage of squalor blades?

c. What is bleed band how to check explain?

4. a. If mass flow rate is 60 lb/sec/engine and exhaust gas velocity is 1300 ft sec for a turbojet engine ready for the take off find out gross thrust of each engine

b. Draw by graph effect air thrust for following variable

(i) Speed of a/c

(ii) RPM

(iii) Altitude

(iv) OAT

5. a. Which type of turbine is used in air turbine starter explain

b. What is engine inlet roster clissipate

c. Advantage of reverse flow combustor, explain the work

d. What are advantage of free power turbine and where it is used?

ANSWERS

1C11A21A31A41D

2C12B22A32A42D

3D13A23A33A

4A14D24A34A

5A15A25A35A

6D16D26A36D

7D17B27A37A

8A,D18D28C38B

9D19A29B39A

10D20B30A40C

JET ENGINE

JUNE 1998 SESSION1. Internal energy of a gas depends upon its

(a) Pressure

(b) Temperature

(c) Volume

(d) None of the above

2. When mechanical energy is converted into heat energy or vice versa an exact equivalent exists between the two. This is stated in the

(a) First law of thermodynamics

(b) Second law of thermodynamics

(c) Third law of thermodynamics


3. During starting an engine stabilizes at idle r.p.m and JPT

(a) Check for whether oil pressure is correct

(b) Check for whether oil temperature is correct

(c) Check for whether generator output is correct

(d) All of the above correct


(a) Fuel trimmer is provided so that the relationship between fuels flow an r.p.m. Can be varied without using fuel lever

(b) Because the mass flow inside the engine change with atmospheric conditions

(c) Trimmer is adjusted to provide given JPT.

(d) All of the above are correct

5. During start engine rotates but fails to light up one suspect

(a) Ignition system fault

(b) Fuel pressure control system fault

(c) Both a and b

(d) Battery capacity is low

6. During inspection of centrifugal compressor blades normally

(a) No crack is allowed in the leading edge trailing edge and blade tips

(b) Negligible crack is allowed as in (i) up to minimum extend possible and under constant monitoring

(c) Nicks dents in the leading edge, trailing edge and blade tips not allowed


7. The lowest r.p.m. at which a rotating object vibrates

(a) Resonance

(b) Natural frequency of vibration

(c) Harmonics


8. (a) At high power settings the noise generated from the compressor blade is predominant

(b) Noise from the compressor is of lower frequency

(c) Low frequency sounds can be attenuated easily


9. Characteristics of P & D valve

(a) Dump valve is spring loaded close

(b) Pressurizing valve is spring loaded open

(c) Pressurizing valve limits starting fuel to primary manifold


10. In a jet engine V.S.V and variable I.G.V are a part of

(a) High pressure system

(b) Low pressure system

(c) Accessory drive


11. Modular construction in a jet engine

(a) Enables maintenance with limited repair

(b) Enables maintenance with major repair

(c) Modular maintenance involves more of repair rather replacement

(d) Both b and c

12. Smoke from tail pipe. Most probable cause is

(a) Main oil filter contaminated

(b) Blocked scavenge port of bearing housing

(c) Both a and b


13.In a flight from Delhi to Bangalore, excess oil was consumed than required most probable cause could be

(a) Defective centrifugal breather carbon seal

(b) Main oil filter contamination

(c) Oil leak from contamination

(d) Both a and b

14. In the relation P.V X T the term X is proportional

(a) Mass of the gas molecules

(b) No of gas molecules

(c) Pressure volume and temperature

(d) Average K.E of the molecules

15. If a system is perfectly conducting to the surroundings and the temp remains constant the process is

(a) Isothermal

(b) Adiabetic

(c) P.V constant

(d) Both b and c

16. An aircraft is designed to fly at 350 m.p.h.

(a) Jet engine becomes the choice

(b) Propeller

(c) By pass engine


17. An airplane has an engine providing 4000 lb thrust at 300 m.p.h the thrust horsepower is

(a) 4000 b.h.p.

(b) 3200

(c) 12800

(d) 5000

18. Increase in the turbine disc diameter under hot running

(a) Disc growth

(b) Disc rock

(c) Has effect of reducing tip clearance as engine run time increases


19. When change in pressure and volume of a gas take s place without change in temperature the process

(a) Is very slow

(b) Obeys boyles law

(c) Adiabatic change is quick


20. Oil pressure continuously fluctuates

(a) Indicates is faulty

(b) Pressure relief valve is sicking and contaminated

(c) Both a and b

(d) Oil check valve setting is improper

21. After flight is over engine does not shut down

(a) Loose connection of power lever linkage

(b) Fuel control shut off valve is faulty

(c) Power lever rigging is improper


22. After engine starts the engine hesitates for 5-6 seconds go for

(a) Surge bleed valve check

(b) Solenoid controller check

(c) Fuel pump functional check


23. During testing of engine, hooting/ humming sound is heard

(a) Operation of compressor bleed valve is improper

(b) Condition of the bleed valve diaphragm is bad

(c) Both a and b

24. For M.E.C and P.M.C

(a) M.E.C provides an electronic override of P.M.C to set corrected fan speed

(b) P.M.C provides an electronic override of M.E.C to set corrected fan speed

(c) P.M.C is located in the tail of the engine


25. Start valve can be operated

(a) Manually

(b) Electrically

(c) Opening /closing is indicated by pneumatic pressure


26. In engine starter system

(a) Compressed air pressure is converted to rotational mechanical energy

(b) Reduction mechanism of gear train converts low speed high torque of turbine wheel into high specific low require through a pawl and ratchet mechanism

(c) Starter operation is not controlled by start valve


ANSWERS

1B

11A

21B

2A

12B

22?

3D

13D

23?

4A

14C

24B

5?

15B

25?

6A

16B

26?

7B

17B

8A

18B

9C

9B

10A

20B

Jet Engine (Fed 2003 Session)

1. If jet velocity is 1288ft sec & airflow is 125lb what will be thrust produced?

(a) 4000 lb

(b) 6000 lb

(c) 5000 lb

(d) 3500 lb

2. If atmospheric temperature change but EGT remains unchanged during ground run but every define high power cruise flight then snag/fault is in

(a) CIT

(b) CDP

(c) FCU

(d) FCU altitude adjuster

3. In a turbo fan engine airflow is 60 lb in both fan and core engine exhaust and velocities are sec & -------- ft / sec what will be thrust produced?

(a) 1433 lb

(b) --------lb

(c) 5433 lb

(d) --------lb

4. CIT indicator in turbojet engine is

(a) Copper constraint

(b) Nickel platinum

(c) Chromel alumel


5. FACDEC means

(a) Full authorized digital electronic control

(b) Full authorized digital electronic control

6. Synchronous motor type fuel quantity gage measures

(a) Fuel volume flow

(b) Fuel mass flow

(c) Its same of vane type indicator

(d) As 02 & 03

7. In water injection system EGT is increased water injected at

(a) Inlet

(b) Diffuser

(c) Nozzle

(d) Simultaneous inlet & diffuser

8. If water injection is ON then

(a) N1 spool shifts towards stall margin

(b) N1 spool shifts away stall margin

(c) N2 spool shift away stall margin

(d) N1 & N2 shift away stall margin

9. High power to weight ratio is

(a) Starter motor

(b) Starter generator

(c) Air turbine starter

(d) Rachet & pawl

10. During installation of thermocouple length of sensor is increased then

(a) Under read

(b) Over read

(c) Equal read


11. During feathering of the propeller

(a) Pitch angle fine

(b) Pitch angle course more

(c) Pitch angle negative

(d) As 1 & 2

12. Aluminum propeller is cleaned by

(a) Acid

(b) A caustic solution

(c) None of the above

13. Due to fatigue stress in turbine blade

(a) Change of shape

(b) Cracks in the trailing & leading edge perpendicular to length

(c) Length will grow


14. Due to fatigue stressing turbine blade

(a) Change of shape

(b) Cracks in the trailing & leading edge perpendicular to length

(c) Length will grow


Answers: 1 c, 2 a, 3 - , 4 b,c, 5 b,c, 6 b, 7 a, 8 - , 9 c, 10 a, 11 a,

12 c, 13 d.

15. In which engine air speed kinetic energy at inlet is not changed in the static energy

(a) Turbofan

(b) Turbojet

(c) Turbo shaft

(d) Turbo prop

16. Synchronous system in propeller is used in

(a) Single engine to equal the blade angle

(b) Multiengine to allow same speed of engines

(c) As 1 & reduce vibration

(d) All the above

17. During flight which fault is not monitored by performance monitoring

(a) EPR, EGT, PRM

(b) EPR, EGT max, CIT

(c) CIT, CDP, EGT max

(d) CIT, CDP. EGT, RPM

18. If oil is found in exhaust

(a) Replace engine

(b) Seal leakage at bearing shaft

(c) Carbon seal leakage in turbine shaft

(d) Scavenge pump failure


(a) Pressure pump capacity is greater than scavenge pump capacity

(b) Scavenge pump capacity is greater than pressure pump

(c) Both pump capacity are same

(d) --------------------------------------

20. Gas velocity is high at

(a) Inlet

(b) Compressor

(c) Turbine

(d) Diffuser


(a) Supervisory EEC develops command top actuate FCU

(b) Supervisory EEC directly controls FCU

(c) Supervisory EEC and sigma Hydro-mechanical fuel control unit

(d) All of above


(a) ACC controls tips clearance by cooling turbine case

(b) --------------------------------------------------------------

(c) --------------------------------------------------------------

(d) --------------------------------------------------------------


(a) Turbo jet engine has lowest TSFC

(b) Turbo fun has better hot day performance

(c) Turbo fan has lowest TSFC up to 400 mile / hour



(a) Actual power output of engine as compared to the horsepower in fuel is thermal efficiency

(b) Propulsive efficiency is the thermal efficiency

Answers: 14 d, 15 c, 16 b, 17 c, 18 b, 19 b, 20 c, 21 c, 22 a, 23 c,

24 a.

25.What is the effect of combustion emissions?

(a) Populates surrounded area

26. EPNAB means effective perceived noise decibel

(a) Sound is dissipated at distance

(b) __________________

(c) It is standard measure of the loudness (Sound or) combined with frequency and duration of sound and is used specify for a/c noise in hemisphere

(d) Soap - spectrographic oil analysis port spectrum tric oil analysis program


(a) In the flight CDP failure cause to run engine in idle

(b) During starting CDP failure cause huy start

(c) During ground CDP failure will cause to run engine idle

(d) Any time CDP failure to run engine higher rpm

28. Polished shaft is used for which bearing

(a) Carbon bearing

(b) Labyrinth bearing

(c) Nylon bearing


29. Trimmer coil add in ignition system is

(a) Convert AD to DC

(b) Convert DC to AC

30. Difference between hi voltage of 10-voltage ignition

(a) Hi voltages have high energy than 10 voltages

(b) Hi

31. During oil analysis mg is gived Hi then a practice gear of problem in gearbox

Answer: 25 - , 26 - , 27 b, 28 a, 29 b, 30 a, 31 - .

JET ENGINE SUBJECTIVE (FEB 2003 SESSION)

1. What is cascade, how it helps turbofan / turbojet engine explain?

2. Wright the types of thrust reverser. Explain mechanical blockage type with sketch

3. What are the advantage & disadvantage of centrifugal compressor?

4. What is primary principal of pressurization breather system explain pressurization breather system with sketch how it works?

5. What is vortices dissipater explain with sketch?

6. Explain the operation of HMF unit metering vale with sketch?

7. What are causes of oil temperature high give remedial action for each cause?

8. What are the combustor emissions give their effect?

9. Wright the operating principal of turbojet and ice separator inlet screen?

10. What are the forces acting on rotating propeller explain each?

11. Wright principal of Hamilton propeller feathering with sketch?

12. Explain the procedure for finding ------------ of the oil engines?

13. What is slip explain?

14. Explain how turbofan engine is replacing turboprop engines

15. What are the FOD avoiding precautions turboprop engines?

16. Using Newtons seonel 100 of notion derive formula for thrust calculation

17. What is the not streak explain give reason for streak

18. FFX, FPM & EGT northern what are causes remedial action?

32. In the good combustion chamber

(a) Increase velocity

(b) Diffuse

(c) Convert pr to kinetic energy

(d) As 1 or 2

33. In hi energy capacitor ignition system

(a) In hi energy capacitor ignition system

(b) Hi energy is produced spark

(c) Hi energy is produced spark using short time

(d) Lo energy is produced spark using short time

34. Acceleration of deceleration is controlled for

(a) Blow out provision

(b) Crack of leading of blade and case

(c) Expansion and contraction of blade and case

(d) None of the above are correct

35. In HMF unit hydro mechanical fuel unit

(a) Valve area is varied (fixed pr. df)

36. For good lubrication oil used synthetic oil

(a) Minimum wax sulpher us sediment

(b) Operates in hi temp is gives low vapour

(c) Very load carrying capacity


37. If anti ice valve is operative in flight then what is positive mean of finishing that anticity system working properly

(a) EGT increase

(b) RPM & EPR fluctuation

(c) Fuel flow rate

(d) As in 1 & 2

Answers: 32 b, 33 b, 34 a, 35 - , 36 d, 37 a, d.

JET ENGINE (JUN 2003 SESSION)

TOTAL MARKS 80

TIME 2 HOURS1. Torque meter is used in

(a) Turbofan

(b) Turbo shaft

(c) Turbo prop



(a) Throttle control & propeller control is interconnected I the ground operation

(b) In flight propeller control is interconnected in the ground operation

(c) ---------------------------------------------------------------------------------

(d) Both 1 & 2

3. If throttle of constant speed propeller is reduced slightly

(a) Pitch angle reduce

(b) Pitch angle increase

(c) Pitch angle remains same

(d) Pitch angle will reverse

4. Antiicing operation check is viewed by

(a) Fl}ctuation of RPM$

(b) Fluctuation of EPR

(c) Flickering of antiicing val~e

(d) TGT increase

5. Notch in turbine blade is

(a) To measure wear

(b) Relieve stress

(c) Giving thickness

(d) Air seal

6. Aluminum propeller blade cleaning is done by

(a) Acid

(b) Caustic soda wash

(c) None


(a) Governor speed progressively increases as load added

(b) Governor speed progressively decreases as load added

(c) Governor speed remains constant as load added

(d) Governor speed remains constant as load removed


(a) Governor droop is decrease of speed when load added

(b) Governor droop is increase of speed when load unloaded

(c) Droop makes stable


9. Mark the correct statement regarding ass flow rate

(a) Proportional to pressure & inversely proportional to temperature

(b) Proportional to pressure & temperature

(c) Proportional to temperature & inversely proportional to pressure

(d) Proportional to temperature & inversely proportional to square root to temperature

10. In modern APU

(a) Load control valve can be adjusted only after shut down

(b) Load control valve works in conjunction of surge valve

(c) Clockwise rotation of trimming means increasing


Answers: 1- b, 2- d, 3 - a, 4 - d, 5 - a, 6 - c, 7 - b, 8 d, 9 d, 10 b.

11. Compressure blade is loose fit due to

(a) Reduce vibrational stress

(b) Ease of removal

(c) Temperature compensation

(d) All of above

12. If EPR reads 2.4 then turbine discharge pressure is 2.4 times of

(a) Inlet static pressure

(b) Inlet ram pressure

(c) Ambient pressure

(d) Compressure inlet total pressure

13. Last chance filter in the oil system screen type

(a) Cleared during engine overhaul

(b) Prevent clogging of jet

(c) Cleaner during 100 hrs inspection

(d) Both 1 & 2

14. Engine preservation depends on

(a) Times remains inactive

(b) Duration of preservation

(c) Depends on engine rotation


15. Mark correct statement regarding double$entry centrifugal compressor

(a) Prevent tip velocity loss

(b) Air entry from both side of comrpessure

(c) Required big inlet chamber


16. After burner thrust augmentation

(a) Thrust of basic engine can be increased

(b) Thrust increase by after burner for take off climb for military aircraft

(c) Both 1 & 2 are correct


17. If JPT is high then water is injected in

(a) Inlet

(b) Diffuser

(c) Both

(d) Combustion

18. If water is injected in the diffuser

(a) Mass flow increased in entire engine

(b) Less pr. & temp drop in turbine hence more pr. in tail

(c) ----------------------------------

(d) All are correct

19. I water in injected in the inlet and diffusers

(a) N1 shift towards surge

(b) N1 shift away surge

(c) N2 shift away surge

(d) Both N1 & N2 away surge

20. Variable propelling nozzle is used due reduce TSEC

(a) By pass engine

(b) After burner

(c) Water injection

(d) All of above

21. Velocity in combustion chamber is reduced

(a) Increased static pr

(b) Ease of burning

(c) ----------------------

(d) ----------------------

22. Stable combustion means

(a) Low emission

(b) Combustion alighted over long range

(c) As 1 & 2

(d) --------------------------------------------

23. In can annular liner

(a) Continues shroud

(b) Circular & outer

(c) Inner & cylindrical

(d) As 2 & 3

Answers: 11 d, 12 d, 13 d, 14 d, 15 d, 16 c, 17 a, 18 b, 19 c, 20 b,

21 b, 22 c, 23 c.

24. Mark incorrect statement regarding combustion chamber drain valve

(a) Mechanically operation by spring force

(b) Failure of valve gives false start

(c) Located in LH or RH side bottom


25. Canted vanes in the first few stage of compressor

(a) Increase pressure

(b) Increase velocity

(c) Increase temperature

(d) Reduce boundary layer separation

26. Knife edge (profile) blade

(a) Wears & sets tip clerance

(b) Used in supersonic aircraft

(c) Is not used

(d) Used in turbine blade

27. Repair of compressure or fan blade is called

(a) Grinding

(b) Brinelling

(c) Galling

(d) Blending

28. Balancing of compressure

(a) Individual stage is balanced

(b) As a unit balanced

(c) Both 1 & 2

(d) Not required

29. Turbine blade design is based on

(a) Corrosion resistance

(b) Creep

(c) Fatigue & vibration resistance

(d) Both 2 & 3

30. Fatigue stress causes

(a) Elongation of blade

(b) Crack in LE & TE

(c) Change of shape

(d) All of above

31. Mark current statement regarding radial inflow turbine

(a) Air enters at eye & leaves at radial outward

(b) Usmd in big engine

(c) Air enters at peripheral nozzle & flows radial inward

(d) As 2 & 3

32. Function of NGV is

(a) Convert TE to KE

(b) Convert$KE to PE

(c) Directs air perpendicular to bucket

(d) As 1 & 3

33. In pure turbojet engine temperature drop across turbine is

(a) Same as compressor

(b) About same as compressor

(c) Higher than compressor very low than compressor

(d) Very low than compressor

34. For load balancing in the turbine rear stages

(a) More turbine area is required

(b) More length is required

(c) Less turbine area is required

(d) As 1 & 2

35. If exhaust nozzle area is decreased

(a) CDP increases

(b) CDP decreases

(c) SFC decreases

(d) As 1 & 3

36. What component prevent stall during low speed ground operation

(a) Bleed valve

(b) P & D Valve

(c) Chock Valve

(d) As 1 & 2

Answers: 24 c, 25 d, 26 a, 27 d, 28 c, 29 d, 30 b, 31 d, 32 d, 33 b,

34 a, 36 a.

37. During starting starter & fuel flow are ok, but hung start cuase is

(a) CDP sensor loss

(b) CIT loss

(c) -----------

(d) -----------------------


(a) Engine running at high RPM & CDP lost then stabilize at idle

(b) Engine running at idle RPM & CDP lost then stabilize at high RPM

(c) CDP lost during starting it is a hung start

(d) All are correct

39. Minimum fuel flow is critical

(a) Acceleration

(b) Deceleration

(c) Idle

(d) Ground run

40. Which component is not installed in the engine?

(a) Fuel pump

(b) FCOC

(c) Filter

(d) Boost pump

41. Deareator is located in

(a) Scavenge sub system

(b) Pressure sub system

(c) Inlet of the pump

(d) Oil tank

42. After engine shut down oil found in the exhaust

(a) Seal failure

(b) Bearing seal failure

(c) Replace engine

(d) Air pressurization seal failure

43. Air tight seal is

(a) Carbon seal

(b) Ring seal

(c) Multi grove seal

(d) Threaded seal


(a) Pressure pump capacity is scavenge pump

(b) Scavenge pump capacity is more pressure pump

(c) Both pumps capacity

(d) As 3 & both are located in oil system

45. Mg is found in SOAP analysis then failure is

(a) Gear

(b) Gear box

(c) Bearing

(d) Bearing shaft

46. Oil SOAP analysis then failure is

(a) Pin point impending failure

(b) Take sample for entire engine life

(c) First semple gives food analysis

(d) As 1 &$2

47. Property of lubricating oil is

(a) High flash point

(b) Low flash point

(c) High pore point

(d) Low viscosity index

48. Synthetic oil is used in turbojet engine


(b) Low carbon / wax formation

(c) High temperature operation

(d) All the above

49. Input to hydro-mechanical FCU

(a) Burner pressure compressure inlet pressure EGT

(b) Burner pressure compressure inlet pressure, RPM

(c) ----------------------------------------------------------

(d) ----------------------------------------------------------

Answers: 37 b, 38 c, 39 b, 40 d, 41 d, 42 d, 43 c, 44 b, 45 b, 46 d,

47 a, 48 d, 49 b.

50. In part EEC system

(a) Control till part throttle and then switch off.

(b) -----------------------------------------------------

(c) -----------------------------------------------------

(d) It is like FADEC

51. In supervisory EEC

(a) Develops command

(b) Control standard hydro-mechanical system

(c) Control valve

(d) As 1 & 2

52. Acceleration & deceleration control is

(a) Flam blow out

(b) To prevent over flow

(c) For max speed

(d) -------------------------

53. High power to weight ratio is in which starter

(a) Electric starter

(b) Starter generator

(c) Air turbine starter

(d) Pawl & ratchet starter

54. White repair AME increased length of thermo-couple

(a) Over read

(b) Under read

(c) No effect

(d) Over read at hi temperature

55. During feathering pitch angle

(a) Course & higher

(b) Low pitch

(c) Course

(d) Negative

56. Propeller lock LP solenoid

(a) -------------------

(b) -------------------

(c) -------------------

(d) -------------------

57. EGT gauge yellow amber arc

(a) Maximum continues to maximum permissible

(b) Minimum to continue

(c) Maximum

(d) As 1 & 2

58. Torque is measured by

(a) Helical gear

(b) Rack & pinion

(c) Spur gear

(d) Planetary gear

59. As altitude increases stall margin

(a) Reinold No. Effect

(b) Increases thats why aircraft flying only at high altitude

(c) Decreases

(d) ---------------------------------------------------------------------

60. Trimble coil in ignition system

(a) Connected parallel to primary capacitor

(b) Connected series to primary capacitor

(c) Not used in ignition system

(d) Used in starting system

Answers: 50 - , 51 b, 52 a, 54, b, 55 a, 56 - , 57 a, 58 a, 59 - , 60 a.

JET ENGINE OCT 2003

61. Shaft engine forward bearing is

(a) Baller bearing

(b) Roller bearing

(c) 1 + is locator bearings

(d) 2 + is takes radial load

62. MCS

(a) APU generator frequency is maintained by CSD and is constant speed rated

(b) APU does not have CSD in its operation and is constant speed rated

(c) APU generator requires axial flow compressor and is constant speed rated

(d) Both B and C are correct

63. MCS

(a) In turbo-jet TSFC increases as airspeed increases

(b) In turbo prop TSFC decreases as airspeed increases

(c) In turbo prop TSFC increases as airspeed increases up to 450 mph

(d) Both A and B are correct

64. MCS

(a) Temp drop through turbines is greater than that of temp rise through compressor

(b) Temp drop through turbine is same as the temp rise through same no of stages of compressor

(c) Temp drop through turbine is about the same as that of temp rise through compressor

(d) Temp drop through turbine is less that that of temp rise through compressor

65. TSFC is

(a) Directly proportional to the rpm

(b) Directly proportional to the efficiency

(c) Inversely proportional to the efficiency

(d) Directly proportional to the compressor ratio

66. Primary function of inlet duct is

(a) To convert kinetic energy of rapidly moving air stream into ram pressure rise

(b) To convert potential energy into kinetic energy inside the duct

(c) To convert potential energy into ram pressure rise inside the duct

(d) To convert kinetic energy into potential energy outside the duct

67.Compressor inlet screens

(a) Are found in rotorcraft TPE and ground turbine installations

(b) Are sued mostly in axial flow turbojet engines

(c) A + have problems of icing and fatigue failure

(d) B + if fitted they may be located either the inlet or the compressor inlet

68. Two shaft whose axes are at an angle to one another but in the same plane to gear used

(a) Bevel gear

(b) Spiral bevel gear

(c) Spur gear

(d) Helical gear

69. Prime requirement for stator anes is (RR31)


(b) Fatigue strength

(c) Smooth surface finish

(d) Heat resistance

Answers: 61 d, 62 a, 63 d, 64 c, 65 c, 66 a, 67 c, 68 b, 69 b.

70. Function of P & D valve is

(a) Flow divider

(b) Dumping fuel after engine shut down

(c) Fuel pressure control


71. Propulsive efficiency of high by pass turbofan is high due to

(a) Same length

(b) Small turbine

(c) Small dia

(d) All correct

72. AMEs knows OAT is significantly shifted but TGT is same at ground. In the high power run every thing is normal then snag is

(a) CIT system

(b) CPP system

(c) FCU temperature compensator

(d) Throttle missrig

73. Trimming means

(a) Adjustingidle & max power

(b) Adjusting exhaust nozzle

(c) Adjusting throttle for full forward


75. There is a problem in the turbine then

(a) Vibration increases with RPM increases

(b) Vibration decreases with RPM increases

(c) No change of vibration


76. Ignition plug correct statement (Compare to PE)

(a) Wider gap

(b) Less fouling problem due to high spark

(c) -----------------------------------------------

(d) As 1 & 2

77. Propeller feather

(a) Electric cut out switch

(b) ---------------------------

(c) ---------------------------

(d) ---------------------------

78. Part throttle

(a) Throttle movement less than full forward

(b) -------------------------------------------------

(c) -------------------------------------------------

(d) -------------------------------------------------

79. ----------------------------------------------------

(a) ------------------------------------------------

(b) -----------------------------------------------

(c) ------------------------------------------------

(d) ------------------------------------------------

Answers: 70 d, 71 a, 72 a, 73 a, 74 a, 75 a, 76 d, 77 - , 78 - , 79 - , 80 - .

1. Engine performance check needed

(a) To see mechanical integrity of the engine

(b) Instrument check

(c) Power check

(d) All are correct

2. Modern aircraft engines

(a) Have many drain holes at different location to drain volatile fluid used inengine

(b) There are no such drain holes provided

(c) FCOC has provision for draining

(d) Both A and C are correct

3. MCS

(a) Compressor and turbine discs are forged by powder metallurgy

(b) Compressor blades and vanes are generally cast

(c) Turbine blades and vanes are made by lost wax method

(d) All are correct

4. Run down time is (RR 261)

(a) Time taken by the engine to come to rest after closing the shut off valve

(b) It gives indication of wear or rubbing inside the engine

(c) Wind velocity and direction may affect the RDT of an engine

(d) All are correct

5. Sound suppressors used in gas turbine engine to

(a) Reduce energy

(b) Increases frequency

(c) Increase eddies

(d) All are correct

6. MCS regarding jet cal analyzer

(a) Used to check EG thermocouple during engine run or without running

(b) Used to check continuity and resistance of the EGT circuit during engine run only

(c) Used to check % rpm. During engine run only

(d) Both B and C are correct

7. Oil pressure indicating system is

(a) Auto sync

(b) Thermocouple

(c) Resistance

(d) Synchronous

8. Major disadvantage of air turbine starter is

(a) It produces low torque

(b) Requires high volume of airflow

(c) Complex construction

(d) Limited to small engine

9. MCS

(a) Igniter plugs have problem of corrosion of case, and after prolonged use it get eroded

(b) The audible test for proper ignition check is not possible in synchronous ignition

(c) Iridium inserts are placed in the tip to prolong its lift

(d) All are correct

Answer: 1 c, 2 d, 3 d, 4 d, 5 b, 6 c, 7 a, 8 b, 9 d.

10. Engine inference

(a) Nozzle diaphragm area is measured at the exit of the vanes

(b) Total outlet area measured is the sum of all areas of the passages between the vanes

(c) Nozzle area effects the efficiency of the engine

(d) All are correct

11. Hydromantic pitch propeller

(a) Is constant speed counter weight type propeller

(b) As in A also used for full feathering

(c) As in B also used for reversing operation

(d) As in C also used for maneuverable pitch change

12. Oil found in gas path

(a) Inoperative scavenge pump

(b) Fuel leak in oil system

(c) Low vent pressure

(d) None of the above is correct

13. When water is injected in inlet alone

(a) N1 will move away from stall

(b) N2 will move away from stall

(c) N1 will move towards stall

(d) Both N1 and N2 will move away from stall

14. Trimming is carried out

(a) To set idle to max rpm

(b) To adjust acceleration and deceleration

(c) To limit exhaust gas temperature

(d) To set compressor bleed valve opening

15. In centrifugal compressor engine thrust is determined by

(a) RPM

(b) EPR

(c) EGT

(d) TORQUE

16. Increasing NGV area will cause

(a) N1 increase

(b) N1 decrease

(c) TSFC decrease

(d) N1 no change

17. For a given compressor rpm if airflow increase

(a) Compression ratio increases surge margin decreases

(b) Compression ratio increases surge margin increases

(c) Compression ratio decreases surge margin increases

(d) Compression ratio increases surge margin increases

18. If bypass valve is fitted across the metering valve, and P1 is inlet pressure and P2 is outlet pressure then constant fuel pressure differential is depends on (Tr.273)

(a) P2 P2

(b) Orifice area

(c) Metering valve

(d) Bypass valve

Answers: 10 d, 11 - , d, 12 a, 13 a, 14 a, 15 a, 16 - , 17 a, 18 d.

19. Two internal sections of an engine are subjected to different air per seel to be used

(a) Thread seal

(b) Ring seal

(c) Multi grooved seal

(d) Carbon seal

20. The afterburner engine liner is perforated

(a) Which is cooled by secondary air

(b) Leads to screech

(c) A and B are correct


21. In a hydro mechanical torque meter if the temperature of oil is increased causes

(a) High torque reading

(b) Low torque reading

(c) No change

(d) Any of the above

22. Most prevalent condition for icing is

(a) High rpm low airspeed

(b) High rpm high airspeed

(c) Low rpm low airspeed

(d) High rpm high velocity

23. MCS

(a) Electrical heaters are mostly preferred than pneumatic heating for anti-icing system

(b) Isopropyl alcohol or phosphate compounds are used for deicing system

(c) Anti icing heating is commanded through cyclic timers


24. Turbo shaft with free turbine, its speed is controlled by

(a) Ng governor

(b) Nf governor

(c) Idle governor

(d) Not controlled by governor

25. The oil system used by VTOL engine is

(a) Full flow

(b) Hot tank

(c) Total loss (expandable)

(d) Pressure relief valve

26. In full flow oil system quantity of oil flow is determined by

(a) Take off

(b) Cruise

(c) Ground idle

(d) All rpm range

27. In test house first and last test carried out after overhaul is

(a) Vibration survey

(b) Hot air leak

(c) Engine power setting

Answers: 19 c, 20 a, 21 b, 22 b, 23 d, 24 - , 25 c, 26 d, 27 - .

28. Factory ignition depends upon

(a) Volatility of fuel

(b) Specific gravity

(c) Viscosity

(d) As in A atomization

29. MCS

(a) Turbojet engines used annular combustion for shorter length

(b) Turbojet engines used reverse flow combustion for shorter length

(c) Turbofan engines give best performance

(d) B and C are correct

30. Compression in an axial flow engine is

(a) Isothermal

(b) Adiabatic

(c) Isometric

(d) Isobatic

31. Decreasing nozzle area will cause

(a) Pt7 up*

(b) Pt7 down

(c) Tt7 down

(d) No change

32. Part time fuel control

(a) Used for part power trim

(b) Operates in adverse condition

(c) Operates like hydro mechanical fcu up to max. Power then amplifier takes care

(d) Operates like FADEC

33. Last chance filter is used in

(a) Oil system

(b) Fuel system

(c) Oil tank

(d) Deairator

34. If Pt2 is partially blocked by ice formation

(a) EPR will increase

(b) EPR will decrease

(c) EPR will fluatuate

(d) EPR will not change

35. More than one weld is not carried out in deicing element because

(a) Increases circuit resistance of element

(b) Decreases circuit resistance of element

(c) It will damage the element

(d) All the above may happen

36. The function of selector valve is post exit thrust reverse is

(a) It gives command for reverse operation

(b) It selects the actuator valve to operate thrust reverse

(c) T operates the hydraulic valve to slow and deploy thrust reverse


Answers: 28 d, 29 d, 30 b, 31 a, 32 c, 33 a, 34 a, 35 - b 36 c.

37. Most commonly used oil in gas turbine engine is

(a) Petroleum

(b) Akyl diestar

(c) Polyester

(d) Mineral

38. Mark INCORRECT statement

(a) Screen type filter is used in low pressure

(b) Cartridge type filter is used in low pressure

(c) Screen disk type filter is used in low pressure

(d) Cone shaped filter element is used in screen type filter

39. In turboprop power lever is interconnected to

(a) Throttle lever

(b) Propeller lever

(c) Condition lever

(d) Governor

40. MCS

(a) For a given torque weight of starter generator is less than air turbine starter

(b) Starter generator windings are separate

(c) Duty cycle of starter generator is more critical than air turbine starter


41. In turboprop during starting the positions of levers are

(a) Throttle lever at idle and propeller lever at high pitch

(b) Throttle lever at idle and propeller lever at nay position from high to low pitch

(c) Propeller lever at idle throttle lever at idle

(d) Throttle lever at idle and propeller lever at low pitch setting

42. If oil quantity is increased cause is

(a) Scavenge pump failure

(b) Food faculty

(c) Bearing pressure loss

(d) All of above

43. During starting satisfactory condition for combustion is

(a) Low pressure, high temp, low velocity

(b) High pressure, high temp, high velocity

(c) Low pressure, high temp, high velocity

(d) High pressure, high temp, low velocity

44. Gradual darkening of oil is due to

(a) Degraded oil is used

(b) Inhibitor performing its function properly

(c) Excessive air leak in to the oil

(d) All are correct

45. MCS

(a) Oil bypass valve is installed at inlet

(b) Oil flow through passages depend on the operation

(c) If problem occurs fuel will flow into oil

(d) All are correct

Answers: 37 c, 38 c, 39 b, 40 b, 41 d, 42 b, 43 d, 44 b, 45 c.

46. Thrust of turbofan measured in test cell by

(a) EPR

(b) EPR/NI

(c) Torque meter

(d) Thrust meter

47. In post exit thrust reverse is deployed by

(a) Isolator valve

(b) Selector valve

(c) Shut off valve

(d) Shuttle valve

48. In a constant displacement pump the output volume is 10 gph it actually

(a) Delivery

(b) Displacement

(c) Volumetric efficiency

(d) All are correct

49. MCS

(a) The seal which rides on highly polished surface is carbon seal

(b) Carbon seals are used in vent pressurization system

(c) Both A and B are correct

(d) None of the above is correct

50. In reheat engine with reheat operation

(a) Dry EGT is high

(b) Dry EGT is low

(c) No effect on EGT as it remain same

(d) Wet EGT is high

51. Safety feature incorporated in air turbine starter

(a) Starter shaft with shear neck section shears off when over speeded

(b) Starter turbine gets chocked in case of air inlet valve failure

(c) Any malfunction occurs magnetic chip detector inspection is carried out

(d) All are correct

52. Most important property of turbine blades


(b) Creep resistance

(c) Vibration resistance

(d) Fatigue

53. Property required in NGV


(b) Heat resistance

(c) Creep resistance

(d) Fatigue resistance

54. Prist used in fuel for

(a) Anti-icing

(b) Anti-biocidal

(c) A and B are correct

(d) Anticorrosive

Answers: 46 d, 47 b, 48 b, 49 a, 50 c, 51 d, 52 b 53 b.

55. P & D valve senses

(a) Electrical signal

(b) Rpm

(c) Inter stage pump pressure

(d) All of above

56. Function of NGV

(a) To increases the pressure at its outlet as per Bernoullis theorem

(b) To deflect the gases at desired angle

(c) As in B to increase the velocity of gases at its outlet


57. If any fault occurs in FCOC

(a) Oil will flow into fuel

(b) Fuel will flow into oil

(c) Fuel quantity will increase


58. Water methanol is injected at inlet of compressor

(a) Increases mass airflow through whole engine

(b) Increases the fuel flow

(c) Both A and B are correct


59. Output of gear rotor pump

(a) Proportional to the missing tooth multiplied by no. of teeths on outer gear

60. Breather pressurization system

(a) Keeps the constant pressure in the sump for positive flow of oil

(b) Ensures positive flow of oil to the bearing chambers

61. Angle of blades during starting of turboprop

(a) Fine pitch so that minimum resistance on blades

(b) Coarse pitch so that minimum resistance on blades

(c) Any angle so that EGT should not exceed limit


Answers: 55 c, 56 c, 57 a, 58 a, 59 a, 60 a, 61

JET ENGINE (GAS TURBINE ENGINE)

(OCT 2000)

ESSAY

LIST & EXPLAIN NON DESIGN FACTORS AFFECTING THRUST

LIST FIVE ALLOYS THAT ARE USED IN THE CONSTRUCTION OF GAS TURBINE ENGINE. DE?

PROPERTIES OF EACH THAT MAKE IT ESIRABLE FOR USE IN SPECIFIC LOCATIONS IN THE

DRAW BLOCK DIAGRAM & EXPLAIN A TYPICAL FUEL SYSTEM

DESCRIBE THE GAS FLOW THR A TYPICAL REVERSE FLOW ANNULAR COMBUSTION CHAMBER REQUIREMENTS OF GOOD THRUST REVERSER

WHAT DO YOU UNDERSTAND ABOUT COMPRESSOR STALL LIST THE METHODS TO PREVENT

COMPRESSOR STALL & EXPLAIN ONE

ADVANTAGES & DISADVANGES OF AXIAL & CENTRIFUGAL COMPRESSOR & APPLICATION

CHARACTERISTICS ADVANTAGES & DISADVANTAGES OF

1) TURBOPROP

2) TURBOFAN

3) TURBOJET

EXPLAIN WHAT IS MEANT BY PERFORMANCE MONITORING & DISCUSS ITS IMPLICATION

IMPROVE RELIABILITY OF ENGINE

PROCEDURE FOR LONG TERM STORAGE (PRESERVATION) OF ENGINE

OBJECTIVE

1. A large jet engine handles 100 lb. Sec of air the velocity of this air at the jet nozzle is 659 mph what is the thrust of the engine

F MA F = (Wa / g) A = (100/32.2) (659*1.467) = 3002 LB **(initial speed = 0)

Mark correct statement

1. What the gross thrust is computed

(a) The velocity of the air coming into the engine due to velocity of airplane is disregarded

(b) The loss in thrust involved in taking air in at the front of the engine is known as ram drag, Net thrust is then gross thrust minus ram drag

(c) As in (1) & (2)


2. The complete formula for a turbojet engine with a choked nozzle is

Fn = (Wa/g) (v2-v1) + (Wf/g) Vf + Aj (Pj-Pam)*

3. MCS

1. The rated net thrust of any engine is determined by how much the forward thrust forces exceed the rearward forces

4. MCS

1. At higher altitude pressure continues to drop sharply W.R.T temperature resulting

Sharp drop in thrust

5. MCS

1. Brayton cycle called open cycle

6. Ram recovery point is that

1. A/c speed, which the ram pressure rise is equal to friction pressure losses

7. Engine mfr rate their engine by

Bell month inlet duct

8. British thermal unit is a standard measure of energy defined as the amount of energy reqd to raise the temperature of 1 pound of water to 1-degree faranhit at

(a) Constant pressure

(b) Constant volume

(c) Constant mass


9. Can annular combustion chamber

(a) Greater structural stability & lower pressure drop

(b) Outer case made to slide for line inspection

(c) As in 1 & 2


10. A unique cooling concept reduces cooling air requirements by 50% & decrease weight by 20% the combustor is

(a) Annular

(b) Can annular

(c) Can type

(d) Fin wall

11. Noise protection device is required

(a) Frequency up to 100db

(b) As in 1 with ear plug

(c) Frequency up to 160db

(d) As in 2 with ear protector

12. Water injection coolant freezing point

Any increase in back pressure from exhaust nozzle affects

(a) R.P.M

(b) Compressor stall

(c) E.G.T

(d) All above

13. After burners spray bars

Turbine vane/blade cooling figure

(a) Convection

(b) Impingement

(c) Film

(d) All above

14. In fuel flow control one of the method is

(a) Keeping pr. Drop constant & varying orifice area

15. Droop can be reduced

(a) By using weaker spring

(b) Marking orifice opening more radially

(c) Using by increasing the pressure drop

(d) All above

16. For the fuel pump containing two stages the possible connections are

(a) Series

(b) Parallel

(c) Series-parallel

(d) All above

17. Fuel passage drilled at right angle

(a) Fuel is discharged with a swirling motion in order to provide low axial air velocity & high flame speed

(b) Fuel is discharged with a swirling motion in order to provide high axial air velocity & low flame speed

(c) As in air shroud surrounding the nozzle cools the nozzle tip & improves combustion by

(d) As in reduce the accumulation of carbon deposits on the face

18. High oil consumption

(a) Defective scavenge pump

(b) High sump pressure

(c) As in 1 & 2

19. High intensity means

A lethal charge is present

Identify the figure of igniter plug

Low voltage shunted surface gap

An turbine starter not reaching cut-off self accelerating speed reason

(a) Rotary switch in regulator v/v is not adjusted

(b) Shear off drive shaft

(c) As in 1 & 2

20. Trend monitoring analysis (plot of EGT, N1, N2, VIB, F/F vs TIME)

(a) 1st stage NGV failure

(b) 13th stage bleed v/v cracked

(c) Turbine case separation

(d) All the above

21. SOAP TEST

(a) Pin point the impending failure

(b) Used for trend monitoring

(c) As in 1 & 2

22. Gap between THUMB & FOREFINGER denotes

Slight adjustment

Starting sequence of engine is

Starter ignition fuel

23. Identify seal in figure

(a) Labyrinth seal

(b) Carbon rubbing seal

(c) Magnetic seal

24. Helicopter uses gas turbine engine

(a) Turbo shaft with free turbine

(b) Turbo shaft with fixed turbine

25. Shrouded turbine tip provides

(a) Long blade thin tig

(b) Reduced distortion under load

(c) Dampen the vibration

(d) All above

26. Shingling is due to

(a) Compressor stall

(b) F.O.D

(c) Over speed

(d) All above

JET ENGINE

GENERAL

1. Inlet guide vanes are not present in turbofan engine, in order to

(a) Reduce noise level

(b) Reduce weight of the engine

(c) Increase mass airflow

2. Turbojet engines having axial-flow compressors have what type of rear bearing

(a) Ball

(b) Roller

(c) Taper-roller

(d) Needle-nose

3. Some high volume turboprop and turbojet engines are equipped with tow spool or split compressors. When these engines are operated at high altitude

(a) Throttle must be retarded to prevent over speeding of the two comp. Rotors due to low density air

(b) Throttle must be retarded to prevent over speed of H.P rotor due to low density air

(c) L.P rotor will decrease in speed as compressor load decreases in lower density air

(d) L.P rotor speed does not change with altitude

4. In a gas turbine engine firewalls are provided

(a) To separate the hot zone and the cold zone

(b) To prevent the fuel leaking from the fuel lines to come from the hot section

(c) Both are correct

(d) None

5. The most modern method of cooling turbine blade and nozzle vanes is

(a) Design of hollow blades and hollow nozzle vanes

(b) Film cooling of vanes and blades

(c) Reducing T.I.T

6. Swirling vanes are sued in fuel nozzles

(a) For rapid combustion

(b) To handle more fuel

(c) To handle more air

(d) All are correct

7. Ice formation on engine is

(a) More dangerous than on wing

(b) Less dangerous than on wing

(c) Equally dangero7d as ice formation on wing

8. Flame out occurs in the following condition

(a) Lean flame out low fuel pressure high r.p.m high altitude

(b) Lean flame out low fuel pressure low r.p.m, low altitude

(c) Rich flame out low fuel pressure low r.p.m. low altitude

9. Blade twist is given

(a) For constant air flow along the length

(b) To distribute load along the blade length

(c) To maintain constant outlet pressure


10. At high altitude

(a) N2-N1 is maximum

(b) N1 rotor will rotate faster than N2 rotor

11. In a split spool compressor turbine as aircraft altitude increases

(a) L.P spool increases in speed due to reduction in air density

(b) H.P spool speed decreases to compensate density reduction

(c) H.P spool speed increases to compensate density reduction

(d) Both H.P and L.P spool maintain their original constant speed

12. For proper ignition of air/fuel mixture in the combustion chamber

(a) High compressor discharge pressure high inlet temperature and low viscosity is ideal

(b) High compressor discharge pressure low temperature and low velocity is ideal

13. In a combustion chamber flame out occurs if

(a) There is disturbance in air-flow

(b) Fuel nozzle is clogged

(c) Igniter plug is faulty

14. In an axial flow turbine engine what type of rear bearing is mostly used?

(a) Ball bearing

(b) Roller bearing

(c) Tapered roller bearing

15. Fuel trimming is done in the field only?

(a) To up trim the engine

(b) To compensate the thrust due to blades loss

(c) To compensate the thrust due to contamination of the compressor blade

16. At high altitude

(a) Surge line moves up as r.p.m. line moves down

(b) Surge line moves downas r.p.m. line moves up

(c) Surge line moves up as r.p.m. line moves up

(d) Surge line moves down as r.p.m. line move down

17. Brayton cycle is known as

(a) Constant pressure cycle

(b) Constant volume cycle

(c) Constant mass cycle

(d) Constant combustion cycle

18. What would be the possible cause of a gas turbine engine to have as high EGT high fuel flow and low r.p.m. At all engine power settings?

(a) Insufficient electrical power to the instant bus

(b) Fuel control out of adjustment

(c) Loose or corroded thermocouple

(d) Turbine damage of loss of turbine efficiency

19. The speed of high pressure compressor is less than that HPT because ?

(a) Turbine has more no of blades

(b) Turbine and compressor have same no of blades

(c) Turbine operates at high temperatures

(d) Turbine area is more

20. During trimming at high humidity the effect on jet engine is

(a) Increased P5 and decreased P2

(b) Increased engine trim

(c) Decreased engine trim

(d) No effect

21. Work done W by the compressor as shown when Sp is the specific heat, is expressed as

(a) W = Sp (T1 T2) / m

(b) W = Sp. m. (T2 T1)

(c) W = m. (T2 T1) / Sp

(d) W = m. Sp (T1 T2)

22. For a particular setting the compressor r.p.m. on a hot day compared to a standard day will

(a) Increase

(b) Decrease

(c) Remain same

(d) Nothing can be said firmly

23. Noise reduction at exhaust duct

(a) Changes the low frequency to high frequency

(b) Changes the high frequency to low frequency

(c) Decrease the velocity of the exhaust gases

(d) Decrease the pressure of the exhaust gases

24. The load distribution over a turbine blade as shown in the sketch is for

(a) Impulse type blade

(b) Reaction type blade

(c) Impulse reaction type blade


25 Materials used in engine construction

Compressor Gear box Combustion chamber Exhaust cone

(a) Mg-alloy

Cobalt

Ti-alloy

---

(b) Ti alloy

Mg-alloy

Ni-alloy

Cobalt

(c) Ni-alloy

Aluminum

Ni-alloy

Cobalt

(d) Cobalt

Magnesium

Ni-alloy

Steel

26. A tachometer reads 100% when it is being driven at 4200 r.p.m. If the tachometer drives gear ratio is 0.428:1, what is actual speed of the compressor?

27. Mark the correct statement: Surge is associated with

(a) Sharp uncoordinated aircraft maneuvers

(b) Thrust reverse operation

(c) Afterburner operation

(d) All of the above are correct

28. Match the following in pick up and O/p and O/p signals of the following instruments

(a) Thermocouple

D.C voltage

(b) Accelerometer

Charge

thermocouple d.c. voltage

(c) Speed tachometerD.C signal

speed tachometer a.c. signal

(d) Electronic fuel flowA.C. signal

vibration pick up a.c.

29. If Pt2 blocks partially E.P.R.

(a) Increases

(b) Decreases

(c) Remains the same

(d) Constant

30. Low energy ignition exciter

31. Engine casing a hottest

(a) Combustion chamber

(b) L.P turbine

(c) H.P turbine

(d) Jet pipe

32. In a chromel Alumel thermocouple instrument shown

(a) A is +ve and B is ve

(b) A is green and B is white

(c) A is ve and B I +ve

33. In the adjoining figure, why are the curves for real and ideal conditions different?

(a) Since air is not treated as a compressed gas

Surge

Buzz

Supersonic

Positive incidence stallRear stage stall at high speed

Negative incidence stallfront stage stall at high speed


(a) Whittle combustion chamber has low pressure loss

(b) Annular combustion chamber has low smoke emission

(c) Annular combustion has the most optimum utilization of space

35. Mark the correct statement regarding the cleaning of various engine sections

(a) Hot section cleaning statement is done by

(b) Cold section cleaning is done by vapour degreasing and

(c) Trichloroethylene is not suitable for titanium

(d) All are correct

36. Stagger angle is done for

(a) Wide chord is done for efficiency

(b) Mid span shroud is for stability

(c) First stage fan blade is made from

(i) Al alloy

(ii) Titanium

37. Fire detectors

Bimetallic

Thermistors

Surveillance

Dielectric

(a)Thermocouple

Semi-conductorsInfra-red rays

Capacitance

38. Fuel injector is made for

Square lawCrack pressure

Better pr. At low pr. Inverted flow chamberSimplexDuplex

Centrifugal

Pre-vaporization

Duplex Duplex

Centrifugal

Prevapourisation

SimplexSimplex

Prevapourisation

Centrifugal

Duplex prevapourisationCentrifugal

Pre-vaporization

39. As per international standards organization the following symbols reveal

RestrictorHeater

Absolute

Filter

Cooler

Gauge

40. Fuel scheduling input variable are

N1 and TGT

MEC

Ratio unit

Amplifier

V.S.V

Sensor less F.C.U.

Secondary channel

E.E.C.

41. Match the following

(a) Back pressure valve

Spray nozzle

(b) L.P speed governor

Fuel pump

(c) Dash pot throttle

Annulus

(d) P.R.V

F.C.U. Solenoid

42. Match the following

High oil pressure Oil quantity increases at tankPartially blocked P & D Defective pump Breather pressure leak

Hot start

Seal is broken FCOC leak

Hung start/No start

43. A gas turbine engine is revolving at max r.p.m. If Wa increases

(a) C.P.R increases

(b) C.P.R decreases

(c) C.P.R. remains the same


44. In Reheat, if the C.P.R. exceeds the limit then

(a) Speed governor adjustment is required

(b) Nozzle adjustment is required idle r.p.m. Adjustment is required

(c) F.C.U adjustment is required

45. F.C.U is running at idle. If OAT increases idle r.p.m. is constant, it is due to

(a) C.I.T adjustment

(b) Defective throttle

(c) Speed sensor

(d) C.D.P adjustment

46. If an engineer finds that the EGT reading is less than that of normal it may be dure

(a) Faulty electrical harness

(b) Wire length is shortened during maintenance

47. Jet engine noise

(a) Compressor noise is less than jet pipe noise

(b) Low frequency decays more rapidly than high frequency noise

(c) .

(d) All are correct

48. An air leak is internally at fan duct in compressor aircraft

(a) N1, N2 will increase

(b) EGT will increase

(c) Fuel flow will increase

(d) All are correct

49. If an engine has been started using all components normal and hung start occurs, it may be due to

(a) Closure of surge bleed valves

(b) Opening of surge bleed valves

(c) Lack of lubrication in the bearing

50. If the CSU (constant speed unit) fails, the pilot will maintain

(a) At climb, the r.p.m. Is maintained at climb r.p.m.

(b) At cruise, coarse pitch is constant

(c) At climb, the pilot increase throttle to fly at level flight condition

51. A cascade varies type thrust reverse

(a) Does not take cowl-load sharing

52. When an electronic TGT amplifier fluctuates

(a) Amplification, TGT, N2 sensor all fluctuates

53. Starter has two holes

(a) For alignment

(b) For breather sump vent

54. Exhaust nozzle is changed due to heat after long operation. It will cause

(a) The thrust to reduce for the amount of fuel flow

(b) The thrust will increase with increase in EGT.

(c) No appreciable change in thrust or EGT as area is the same

(d) The thrust will increase due to increase of fuel flow due to more airflow through inlet


(a) Compressors are loaded more in the front stages

(b) Compressors are loaded more in the rear stages

56. Bore scope inspection is does through the holes given. During inspection the HPT shaft is rotated

(a) By removing the starter and rotate through the starter engagement gears

(b) By a drive pad provided for this purpose in the AGB section of the engine

(c) After removing the c/c only, B.S.L can be done

(d) 7/8 socket and spanner attached in the hand cranking pad

57. If the adjustment of the P & D valve on the FCU is lower than normal then

(a) Hot start

(b) Hung start

58. After engine light up the state does not cut off. The probable cause is

(a) Starter cut-off circuit is faulty

(b) Starter drive spring is weak

(c) Starter bleed valve does not close

(d) Either (a) or (b) is correct

59. Hot shift and cold shift of engine is determined by

(a) C.I.T sensor probe condition

(b) T.I.T sensor probe condition

(c) T.L.A and its position w.r.t M.E.C

(d) T.I.T sensor and C.I.T sensor condition

60. Engine anti-icing system condition and

(a) Heats up fwd, and rearward simultaneously

(b) Heats up fwd, and rearward in cyclic operation

(c) Consists of dual butterfly valve, which regulates the hot bleed air in relation with a timer circuit

(d) Can be used in both flight and ground operation

61. L.O.P light illuminates during flight, what are the other parameters (associated with the same) that the pilot has to check on the cockpit indicators?

(a) EGT and r.p.m indicators for the engine malfunction

(b) N1 r.p.m. Gauge and oil temperature

(c) Filter clogging light and EGT

(d) No indicators to check but to cut-off the engine.

62. In the inlet of the hydraulic pump is blocked, what will happen? (Check Feb. 96)

63. In the pressurized chamber of the bearing sump area overboard drain is provided. This prevents

(a) Compressor air contamination

(b) Inward air flow to the chamber

(c) Oil tank overflow


64. What does the graph indicate?

(a) Compressor contamination

(b) Undesirable engine condition

(c) Normal condition

(d) Engine due for overhaul

65. In a turbo shaft engine, the electric starter has carbon brushes, which are worn out. This will

(a) Decrease the starting speed

(b) Not start the engine

(c) Make EGT high

(d) All are correct

66. A turbofan engine, with a hydro-mechanical FCU shows constantly poor r.p.m. Pick-up to maximum power. To detect the snag, mark the correct statement

(a) C.D.P. sensor and N1 Cr

(b) C.I.T. sensor and N2 Cr

(c) R.p.m. sensor

(d) Governor problem

67. The power turbine turbo-shaft is running at higher r.p.m. There is a loss of oil pressure. The most probable cause is

(a) The relief valve stuck in closed position

(b) The relief valve is jammed in open position

(c) Filter clogged

(d) Oil spray jet clogged

68. Which of the following condition, for long time storage of engine

(a) Lip

(b) Cup

(c) Carbon-rubbing

(d) All are correct

69. Engine operation inspection is O.K. except flame out during deceleration. The most likely cause is

(a) Acceleration and deceleration valve

(b) Minimum flow valve setting

(c) Maximum flow valve setting

(d) Governor setting (for maximum speed)

70. Match the following condition, for long time storage of engine

(a) Intake

(b) Fuel system

(c) Compressor

(d) Exhaust

71. Which is the hottest point in the engine?

(a) Compressor casing

(b) Combustion chamber casing

(c) N.G.V casing

(d) Jet pipe casing

72. If C.S.D fails during climb,

(a) r.p.m. Remains the same

(b) Coarse pitch is selected

(c) Throttle is to be adjusted for level flight conditions


73. Partial clogging of P & D valve results in

(a) Hot start

(b) Hung start.

1. Electric motion generator starter used in get engines

(a) Separate starter & generator not reqd

(b) Common armature is used

(c) Two field windings are used

(d) All are correct

2. Air turbine starter used for get eng

(a) Have light to torque ratio low

(b) Reqd. supply of high vol of airflow

(c) Both a & b are correct

3. In auto ign. System

(a) Starter ents of automatically after eng attains self acc. Speed

(b) It is designed primarily to ensure instant a NEOUS ign, if an eng., begins to loose pwr in air

(c) Automatically restarts when flame out occurs

(d) All are correct

4. MCS

(a) The gap at igniter plug is such wider than that of spark plug

(b) As in a tip of igniter plugs not permitted to clean

(c) The ignition of gas turbine eng., is not continuous as used in piston eng

(d) All are correct

5. The problem of droop in governor can be reduced by

(a) Using weaker spring requiring lower force for valve movement

(b) Making metering port narrow so that is requires small movement of the valve

(c) Decrease the pr differential across the metering valve

(d) All are correct

6. Amongst the many inputs to the fuel control it senses

(a) N2 burner pr

(b) As in a ITT, RPM

(c) As in b CIP

(d) As in c CIP

7. HOT SECTION OF ENG. INGLUDE

(a) Comp, turbine, combination

(b) Combustion, turbine, exhaust

(c) Comp, comb, exh,

(d) None above

8. Which is not part of the eng

(a) Main fuel pump

(b) Fuel boost pump

(c) Filter

(d) All are correct

9. MCS regarding centrifugal comp

(a) Pr. Rise per stage is high

(b) Low frontal area

(c) Possible damage to fod

(d) All are correct

10. Lubrication oil use din gas turbine engine have

(a) Low viscosity index

(b) High viscosity index = low viscosity

(c) High pour point

(d) High viscosity

11. When water is injected in diffuser sec

(a) N1 will shift towards stall

(b) N2 will shift away from stall

(c) N2 will shift towards stall

(d) As a & c are correct

12. MCS

(a) Pr pump is gear type scavenge pump is centrifugal type

(b) Pr. Pump is venk type sev pump is gear type

(c) Both of gear type

(d) Pr. Pump is vent type & sev is vene type

13. Propeller blade tracking is the process of determining

(a) The plane of rotation of propeller w.r.t. a/c longitudinal axis

(b) That blade angle within the specified tolerance of each others

(c) The position of tips of the prop. Blades relative to each other

(d) All are correct

14. Angle of attack of blade is defined as

(a) Angle between airfoil section method line & plane of rotation

(b) Angle between chord line & the relative change

(c) Axis of blade rotation during pitch change

15. MCS

(a) Geometric pitch is the distance a propeller should mores fwd in one complete rev.,

(b) Effective pitch is the actual distance a prop move fwd in one complete rev.

(c) Slip is difference between geometric & effective pitch

(d) All are correct

16. Reverse pitch prop

(a) Uses far reducing landing roll

(b) When used high fuel is consumed

(c) All are correct

17. Compressor blades are attached to the rotor by

(a) Fir tree with retention device

(b) Dovetail slot

(c) Bulb type

(d) A & b are correct

18. Thermocouple type egt probes reconnected in

(a) Fir tree with retention device

(b) Dovetail slot

(c) Bulb type

(d) A & b are correct

19. Procedure of reconturing-damaged area of fan blades is called

(a) Blending

(b) Shaping

(c) Burnishing

(d) Blabbering

20. The temp of air is higher in rear stages of comp. This is due to

(a) Diffusion action

(b) Mechanical work. Done by rotor with an

(c) Mechanical energy is converted into heat energy

(d) All are correct

21. The type of eng. Used in helicopter is

(a) Shaft

(b) Prop

(c) Fan

(d) As in a with free turbine

22. Inc., the exhaust nozzle area will result in

(a) N2 dec

(b) Thrust dec

(c) N1 inc.,

(d) As in a with free turbine

23. Diffuser in centrifugal comp

(a) Inc, static pr

(b) Inc, velocity and pressure

(c) Increases kinetic velocity and decreases pressures

(d) Decreases velocity and pressure

24. In the compressor RPM engine speed remain constant and mass airflow increased

(a) Pressure ratio will increase and stall margin will decrease

(b) Pressure ratio will increase and stall margin will inc

(c) Pr. Ratio & stall margin will dec

(d) Ratio will dec & stall

25. TSFC change

(a) Directly by thrust

(b) Inversely by p. ratio

(c) Directly by pr. ratio

26. MCS

(a) Temp drop takes places thru the turbine i.e. approx equivalent to the temp rise occurred in the comp

(b) Temp drop takes place than the turbine is much greater than the temp rise of the comp

27. Stall characteristic of comp. Blade

(a) Begin to in., at higher altitude due to higher Reynolds no., & thus dec., efficiency of the eng.

(b) Remains same on the ground & at higher altitude.

28. Components used in the secondary air thrust reverse type

(a) Blocker door

(b) As in A cascade vane

(c) As in b translating sleeve

(d) As in c thrust

29. In modern jet eng., fue metered fuel by

(a) Airflow may be metered by keeping the pr., drop across the metering valve constant while varying the valve orifice

(b) Valve o

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Jet Engine