DGCA QUESTION PAPER Jet Engine (Feb 2013)
1. Jet Engine operates on
a) Otto cycle
*b) Close cycle
c) Constant volume cycle
d) Open cycle
2. Gas law is
a) P1V1 = P2V2
b) PV = C
*c) =p1v1/t1=p2v2/t2
3. Identify diagram
*a ) Impulse
B) Reaction
C) Impulse-Reaction
4. Synthetic oil is used in GTE
A) More viscous
B) Can take high load
C) Prevent coking and do not effect paint
*D) All
5. Compressor tip speed velocity formula
*a) V=πD rpm
b) V=πD/rpm
6. Squeeze film bearing
*a) Dampens dynamic load
b) Allows system to operate in dry
condition
7. Annular duct
a) Located in the front of fuselage
b) Protudes in the lower side of fuselage
8. Rate of temperature rise detector
a) Continous loop
*b) Thermocouple
c) thermal switch
9. EGT is an indicator of
*a) TIT
b) TOT
10. Which one have a variable area
/rpm
*a) C-D
b) Convergent
c) divergent
11. Water injection in CC
a)increase mass of air in whole engine
*b) decrease T and P in turbine and
increase pressure in nozzle area
12. Wf
lbs , find SFC?
*a) 0.5 lbs/hr
b) 1 lbs/hr
c) 2 lbs/hr
13. TSFC is
a) directly proportional to efficiency
b) directly proportional to compression
ratio
*c) Inversely proportional to compression
14. Thrust reverser
a) should give 70% of forward thrust
b) Pre-exit is done by giving obstruction in
exhaust
c) Post-exit is done by a blocker door
*d) should prevent re-ingestion of gases
through inlet
15. Oil quantity is increased( proofed by
physical test)
a) indicator defective
*b) FCOC leak, fuel into cooler
c) bearing failure
16. Oil through fan blades detected by
a) star mark
b) oil mark
*c) thicker blades in the lower portion
17. Thrust reverser reverses (in High
bypass turbofan)
a) primary airflow
= 700 gallons (6.5 lbs), Fn= 9000
b) secondary airflow
*c) primary and secondary separately
18. Combustion chamber is cooled by
a) secondary airflow throw CC liner
b) holes and louvers in diffuser
19. MTCS
a) duel entry impeller have smaller dia
b) single entry efficiency is less than duel
entry
*c) all
20. MTCS for centrifugal flow
a) impeller collect air and accelerate it
toward diffuser
b) diffuser does not work upon air
*c) all
21. HP required to drive the compressor
a) multiply the specific heat at a constant
pressure by a temperature rise across
compressor will give energy
*b)as in (a) the result is than multiplied
by total weight of airflow through
compressor
c) weight of airflow divided by (a)
22. Caloric value
*a) heat energy per pound of fuel
23. Fire extinguisher is sprayed by
*a) Spray nozzle and perforated tube
b) spray nozzle and calibrated nozzle
24. If methyl bromide is used as fire
extinguisher
*a) Wash the affected area
b) open the engine nacelle for drying and
no wash required
c) send the engine for overhaul
25. In turbo shaft engine if electric starter
is used and carbon brush is worn out
*a) engine will not start
26. Stall is indicated by
a) abnormal noise
b) rpm fluctuate
c) EGT rise
*d) all
27. To correct the front end – low speed
high speed stall condition
a) use bleed valve
b) use VIGV
c) lower blade angle
*d) all
28. In beta range
*a) governor action is blocked out
b) ……….
29. Duct pressure efficiency is
*a) convert KE into pressure energy in
inlet
30. Disadvantage of shrouded turbine
*a) allows the turbine to operate at low
temperature and low speed
b) allows the permit of using thin blades
c) allows bending of blade due to gas load
31. Purpose of knife tip blade
a) cut the air properly
*b) permits a wear fit blade to case tip
clearance
32. Prime factor in comparing engine
*a) thermal efficiency
b) propulsive efficiency
c) volumetric efficiency
33. Lowest TSFC
a) turbojet
*b) turboprop
c) turbofan
34. Thrust in turbojet
a) propulsive forces is the result of
imbalance of forces in the engine
b) long take-off roll
c) largest specific weight
d) all
35. MTCS
a) radial loads are due to aircraft
manouvering and rpm changes
b) ball bearing takes axial and radial load
c) roller bearing takes radial load only
36. Succeeding stages of turbine
a) high gas velocity, pressure and low temp
*b) low velocity, pressure and temp
c) low velocity, pressure and high temp
d) high velocity, pressure and temp
37. Temperature datum valve
a) located between fuel control and fuel
manifold
b) just before fuel outlet
c) trim the fuel flow as temp requirement
38. Speed droop is counteracted by
a) use of weaker spring………
b) decrease spring valve
39. MTCS
a) paper type fiter before fuel pump
b) screen disk after fuel pump
c) screen type before pump
*d) all
40. Gerotor pump
a) single element used in pressure line,
multiple element in scavenge line
b) multi element in pressure line, single in
scavenge
41. Area of turbine nozzle
a) total outlet area is sum of areas of cross
section of passages btwn the vanes
b)……
c) effects efficiengy of engine
*d) all
42. MTCS
a) igniter have larger gap than spark plug
*b) (a) and operate in low pressure
c) gap is more than spark plug
d) © + high pressuire
43. High capacitor ignition system is used
a) high voltage+ high amperage
b) high voltage + high operating life
c) high voltage + high heat intensity
*d) all
44. Igniter…….???
45. MTCS
a)Propeller pitch is difference between
effective pitch and geometric pitch
*b) propeller efficiency depends on slip
46. Hung start
*a) Turbine damage
b) compressor damage
c) fuel malfunction
d) all
47. Engine rumbles
a) P & D malfunction
b) fuel nozzle malfunction
c) cracked air duct
*d) all
48.Motorles mass flow indicator
a) vane is deflected by its restrained spring
b) transmitter rotor is flowed by
synchronous motor
*c) two electrical signals are generated,
indicates mass flow
49. Phase angle is measured by
a) magnetic pick up
b)photo cell
*c)Both
50. APU MTCS
a) load control v/v repaired after shutdown
b) pressure control v/v works in
conjunction witj load control v/v
c)fuel trim clockwise increase
*d) all
51. Turbofan trimming….
52. AME wants to restart after shut off v/v
close
*a) cooling time must be provided
53. Torque meter indicator
*a) measure HP on the gage
b) fluctuates in oil pressure
54. CDP fails
a) surge
*b) flame out
c) deaccelerate to idle
55. Modern vibration monitoring system
a) consist of pick up signal conditioner
display
b)later generation employ pizzoelectric
accelerometer
c)later generation employ velocity pick up
*d) both (a) and (C)
56. Single element fenwall detector
a) use eutectic salt that increase in
resistance with overheat
*b) auto reset when overheat condition
slows
c) does not auto reset
57. Automatic FCU senses
a) CDP
b)CIT
c)EGT
*d) inlet temp + all
58. MTCS
*a) pressure differential constant across
metering v/v , vary orifice area
59. Entrained water is detected by
a) hazzy appearance
b) hydro-kit
*c) both
60. Additives are used for
a) Fungicide
b) de-icing
c) corrosion- resistant
*d) all mandatory
61. Material of centrifugal compressor
*a) Al forging alloy
b) titanium cast
c) titanium-cd alloy
62. Advantage of can type combustion
chanber
a) easy removal
b) easy to control airflow
c)……
*d) all
63. MTCS
*a) Annular chamber has less surface to
volume ratio- less cooling reqd
b) Can type uses available space
64. Auto relight ignition system senses
a) loss of CDP
b) auto bypass starter connection when
power loss occur
c) relight in air/starting
*d) all
65. Excessive air in the direction of
tailpipe
a) high TDP
*b) (a) + low trim
c) low TDP
d) (a) + high trim
66. Wet thrust
*a) take off power when water injection is
used
b) take off power when water injection is
not used
67. High automization of air is achieved by
a) simplex nozzle
b) duplex nozzle
c) dual line
*d) both (b) and (c)
68. MTCS
a) modern fuel nozzle utilize pressure
atomizing type
b) swirl nozzle handle large volume of air
c) multiple nozzle helps in rapid burning
*d) all
69. Advantage of reverse flow combustion
chamber
a) pre heating of air
b) complete combustion
c) shorter length
*d) all
70. Flat rated engine
a) works on conservative part throttle
b) gives full thrust at lower throttle
movement
c) for temp above 15° c thrust can be
achieved by additional throttle movement
*d) all
71. Turbine cooling
a) convection
b) impingment
c) transpiration
*d) all
72. Which factor affects thrust decrease
a) rpm
b) temp
c) airspeed
*d) (b) and (c)
73. In turboshaft , free turbine
a) Speed of free turbine is always greater
than gas generator turbine
b) on load variation gas generetoe turbine
varies keeping free turbine constant
c) fuel governor controls free turbine
74. NTS failure, negative torque is
prevented by
*a) safety coupling
b) propeller brake
c) spur gear
75. TSS is used
*a) auto feather during during flight
76. High temp, fatigue resistance of turbine
is achieved by
a) soil construction
*b) single crystal
77. Can type burner, fuel flow malfunction
causes
a) turbine blade cracks
b) combustion chamber damage
*c) NGV distortion
78. If engine is shut down without cooling
a) cracks in CC
b) cracks in turbine leading and trailing
edges
*c) turbine will squeal and seize
79. EPR is
*a) Thrust indicating system
b) independent of a/c electrical system
c) 3 phase AC and synchronous motor
driven
80. Advantage of centrifugal compressor
a) high pressure rise per stage
b) 800% efficiency by 6 or 7 to 1
c)……
d) all
81. To avoid shock wave—compressor
blade tip speed
a) 1 mach
*b) 0.85 mach
c) 0.7 mach
82. MTCS
a) propeller is of regular waveform
83. MTCS
a) Impulse type turbine blade converts P.E.
to K.E.
*b) Impulse blade have inlet and outlet
same and converts P.E. to K.E.
84. Rate of temp. across turbine is
a) same as temp rise in all stages of the
compressor
b) about same as temp rise in compressor
85. Highest pressure in turbine engine
a) combustion chamber
*b) compressor outlet
c) turbine
86. In imulse-reaction turbine
a) reaction at base and impulse at tip
*b) impulse at base and reaction at tip
87. Function of NGV is
a) convert pressure energy into KE
b) strike the gases at proper angle to the
blades
*c) both
88. What identification should be stenciled
in the area of oil tank filter
*a) oil
b) quantity and grade of oil
c) oil tank filter
89. If high pressure in the bearing chamber
exista and relief v/v spring stucks open
*a) decrease in oil flow through the oil
jets
90. Fuel control unit, sensing unit is
a)fuel pump
b) fuel manifold
c) governor
d) (