10 Feb 2014

DGCA PAPER-3, JET ENGINE Quetions.

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
(d)   None of the above

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
(d)   None of the above

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
(d)   None of the above

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
(d)   None of the above

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
(a)    Corrosion resistance
(b)   Creep resistance
(c)    Vibration resistance
(d)   Fatigue







53. Property required in NGV
(a)    Corrosion resistance
(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 Bernoulli’s theorem
(b)   To deflect the gases at desired angle
(c)    As in B to increase the velocity of gases at its outlet
(d)   None of the above

57. If any fault occurs in FCOC
(a)    Oil will flow into fuel
(b)   Fuel will flow into oil
(c)    Fuel quantity will increase
(d)   None of the above

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
(d)   None of the above

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
(d)   None of the above

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