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Interview Questions

Questions asked in various Interviews conducted by 
Jet Airways, SpiceJet and Indigo

1. Refuelling and defuelling procedure and precautions to be taken?

2.Green Dot at Wheel indicates?

3. What do you know about CAR M?

4. Airlines (Jet Airways) is approved in which category?

5. Wheel change procedure A320, ATR 72, B737

6. Wheel and tire terminology.


7. Why aircraft fuel is measured in pounds or kg instead of liters.

8. Fuel Sampling procedure?

9. Name of tools in general toolbox?

10. Name the LRU's of an engine?

11. IDG is connected to which component?

12. Name of the components attached to AGB.

13. No of Stages of LPC, HPC, HPT and LPT.

14. Tyre pressure for nose wheel and main wheel?


1.         How much is the pressure for refuelling?

Ans: Normally, the maximum pressure for refuelling is 50 psi. [Pressure (suction) for de-fuelling is 11 psi].
Note: The pressure for defueling is kept lower than refuelling. The reason is that the system design, seals and gaskets are so installed to receive higher pressure only in fuelling direction. That is why, defueling pressure is kept low to prevent any damage to the seals or gaskets or other fuelling system components.

2.         If you have to change the starter, from where will you get the new starter?

Ans: The new starter can be procured from the store.

3.         How will you ask the starter from store?

Ans: I will ask for starter mentioning its part number.

4.         Now you are going to change the starter, then you will require some tools (general and special both), procedures etc. From where you will get it?

Ans: I will consult the respective AMM or task card for the information of required general and special tool, procedures etc.

5.         If you have to ask for a new seal from the store, what will you check?

Ans: When a new seal is received from store, the part number, shelf life, packing of the seal is to be checked.

6.         What will you do with the old seal?

Ans: I will cut and throw the old seal.

7.         What is the purpose of diffuser?

Ans: The diffuser diffuses the air just ahead of delivering it to the combustion chamber, thereby increasing the pressure of the airflow and reducing the swirling motion imparted by the last stage compressor rotor.

8.         What is the meaning of diffuse in Basic English?

Ans: In Basic English, diffuse means spreading out.

9.         What is Specific Gravity?

Ans: It is the ratio of density of a definite amount of a substance to the density of same amount of pure water at 4OC.

10.     What is the difference between FADEC and EEC?

Ans: FADEC or Full Authority Digital Electronic Control is a complete system while EEC or Electronic Engine Control is computer. FADEC comprises of EEC and HMU.
We can switch off the EEC without shutting down the engine, but FADEC cannot be switched off or the engine will shut down.
FADEC is only full authority type that means, it controls engine operation throughout its entire range of operation. Whereas EEC may be either full authority type or part scheduling type.
1.          FADEC is a complete system while EEC is a computer and part of FADEC.
2.          If EEC fails, engine will not shut down. But if FADEC fails, engine will definitely shut down.
3.          FADEC comprises of EEC and HMU. That means EEC makes the calculation of amount of fuel to be delivered to the engine and a signal sent to the metering valve to open or close accordingly. Also FADEC controls the operation of VIGV, bleed valves etc.
4.          EEC has a definite location which is generally in the fan frame. However, FADEC being a complete system with a number of components distributed over engine casing cannot be said to have a definite location.

11.     Mallet is classified by?

Ans: Mallet is classified by the material of the head.

12.     What is One Thou?

Ans: One Thou is one part of Thousand or 1/1000 which is also equal to 0.001.

13.     In what unit Fuel Company will provide fuel?

Ans: Fuel companies provide fuel in litres.

14.     Are you working somewhere?

Ans: {at your discretion}

15.     What is dripstick and dipstick?

Ans: Dripstick:               This is a calibrated tube which is fitted in the bottom of the tank and when pulled down, will indicate fuel level in the tank when fuel flows through the tube and exits at the drip hole.
Dipstick:                          It is a calibrated stick which is fitted from the top of the tank and fuel quantity is indicated by mark to which stick is wet by fuel.
Dipsticks and dripsticks are both fuel quantity indicator. The difference is that dipstick is inserted from the top of the tank while dripsticks are installed from the bottom of the tank. Dipstick is dipped into fuel and quantity is measured by the marking to which the stick is wet. Dripstick measures the quantity by the marking which is visible at the edge

of the structure just when fuel started flowing though the tube and exiting through the drip hole.

16.     What is consumable and expendables?

Ans: Consumable are those which can’t be reused for example fuel, engine oil etc.
Expendables are those whose life or period can be expanded such as O-ring, gasket.

17.     Torque formula with extension.

Ans:         𝑇𝑀

= π‘‡π‘’×𝐴


Tw = Torque reading on wrench dial Te = Required torque
A = Lever length
B = Lever length + Extension

18.     Fire Detection system.


19.     What is the size of wire cutter?


20.     What is the duration of last recording of CFDS?

Ans: CFDS records 64 information for the last lag report.

21.     What is moment and momentum? What are their units?

Ans: A moment is the turning effect caused by a force acting at a perpendicular distance from fulcrum is equal to the force multiplied by its arm. Its unit is inch-pounds.
Momentum is the amount of motion contained in a body and is equal to the mass of the body multiplied by its velocity. Its unit is Kgms-1.

22.     How many system is used in aircraft? Description of system.


23.     T/R is used in which system?

Ans: T/R or Thrust Reverser is used in engines.

24.     As mentioned in your resume, you have worked in these aircraft. Which of them don’t have Fly-By-Wire system and why?

Ans: The aircraft who don’t have Fly-By-Wire incorporated are Boeing 747-400 and Boeing 737-800. Both of these airplane are originally build in time when Fly-By-Wire was not developed. So these airplanes were built around technologies available at those times which were mainly dependent on mechanical systems.

25.     What is ATA 20?

Ans: Standard Maintenance Practice.

26.     Torque required on a bolt can be found in?

Ans: AMM.

27.     What is glass cockpit?

Ans: A cockpit configuration that uses digital electronic displays to display the various engine, airframe and flight parameters in place of conventional mechanical gauges. In conventional design, each of the parameters are indicated in almost a separate gauge driven either by mechanically, electrically or pneumatically. However, glass cockpit design replaces most of the conventional gauges with six display unit that display almost every parameter related to engine or airframe or flight operation.

28.     Difference between moment and momentum.

Ans: Moment is the turning effect on a body due to application of a force at a perpendicular distance from the hinge or fulcrum, also termed as arm. On the other hand, momentum is the amount of motion contained in a body.
The moment is mathematically expressed as Ο„ = F * L
The momentum is mathematically expressed as p = m * v

29.     What is the unit of torque?

Ans: The unit of torque is lbs.-inch.

30.     Which hydraulic system uses electrical pump?

Ans: Both yellow and blue system has electrical pump.

31.     RAT details.

Ans: RAT or Ram Air Turbine is an emergency hydraulic pump which is driven by a small propeller exposed to the incoming airstream, called ram air. The RAT is automatically deployed when both green and yellow system has low pressure, both AC buses have failed and the airplane speed is still above 100 knots. A small hydraulic pump generates 2500 psi pressure for blue hydraulic system which is then supplied to most critical systems. Also the hydraulic power drives a Constant Speed Motor/Generator (CSMG) that supplies 115V 400 Hz AC electrical supply at 5kVA rating to the most critical equipment and instruments.

32.     Acceleration and its unit.

Ans: Acceleration is the rate of change of velocity in a particular direction. Its unit is ms-2.

33.     Torque and its type.

Ans: Torque is the force acting on a body that tends to twist the body or tries to make it rotate.
It can also be said as the force that produces angular velocity. The type of torque are:

Dry torque: Torque applied without lubricant is called dry torque. Wet torque: Torque applied with lubricant.
Continuous torque: Torque applied in one direction continuously until desire torque value is reached.
Breakdown torque: It is the maximum value of torque permitted. Running torque: It is the torque required to keep the load moving. Breakaway torque: It is the torque required to initially move the load.
Rundown torque: It is the torque required to overcome the mechanical locking such as when installing self-locking nut.

34.     Tools classification.

Ans: Hammers are classified as hard hammer and soft hammer.
Hard hammers are classified by the weight of the head without handle. Soft hammers or mallets are classified by the type of material of the head. Screwdrivers are classified by shape, type of blade and length of blade.

35.     Auto brake.

Ans: It is a mode of automatic brake application upon landing or during an aborted take-off. When pilot select auto brake from the cockpit, it is energized and applies the braking pressure as selected by the pilot when the ground spoilers are deployed. As a normal procedure, pilot selects MAX in case of an aborted take-off.

36.     How to start engine through APU?

Ans: Pneumatic air is supplied by the APU through a HP Shut-Off Valve to the Pneumatic Air starter.
The starter is rotated which in turn drives the Main Gear Box (MGB). The Main Gear Box drives the Transfer Gear Box (TGB).
The TGB is connected to the HP shaft of the engine, which is then rotated.
The fuel scheduling system schedule fuel and deliver it to the combustion chamber. The fuel is mixed with the airflow supplied by the HP compressor rotation and then burned. Gradually the LP compressor also start rotating.
Thus the engine is started.

37.     State the mathematical equation of momentum.

Ans: momentum = mass x velocity.

38.     When O2 mask system falls?

Ans: In case there is a severe decompression results in the cabin while the airplane is above 14,000 feet altitude, the O2 mask system falls.
It can be stated also as that if cabin altitude crosses 14,000 feet, the O2 mask will
automatically fall.

39.     How to ask tools from store.

Ans: Screwdriver is asked from the store mentioning its point number.

40.     N1 and N2 speed sensor.


41.     What is the location of IDG?

Ans: IDG is located at 6 O’clock position in CFM56-5B.

42.     What is ATA 74?

Ans: Ignition.
43.    General about Flap, Slat, Spoiler, Aileron.
Ans: Flap is the auxiliary high lift devices used to increase lift produced by the wing during take-off and landing.
Slat is also a high lift devices that is used to generate more lift during take-off and landing and also during slow speed operation and thus preventing the airplane from stalling.
Spoilers are used in conjunction with aileron to provide lateral control.
Aileron is a primary flight control surface that provide rolling and lateral control.

44.     Mark down the aircraft in your resume which do not have fly-by-wire. Why do they not have fly-by-wire.

Ans: The aircraft which do not have fly-by-wire technology are Boeing 747 and Boeing 737. Both of the Boeing airplanes are originally designed long ago before invention of fly-by- wire technology. The blue print of the airplane which was originally issued with type certificate did not include provision for fly-by-wire and hence they are not equipped with fly-by-wire.

45.     What is dark cockpit?

Ans: It is a cockpit concept in which, no indicating light will be illuminated when every system and components are working normally. An indicator or warning light will come when there is fault or malfunctioning detected.

46.     What is IDG? Why it is called so?

Ans: The full form of IDG is Integrated Drive Generator. It is a Constant Speed Drive or CSD, integrated with an alternator or ac generator.
Since CSD and the generator is integrated into one housing, it is termed as Integrated.

47.     What is the location of IDG?

Ans: In CFM56-5B installed in Airbus A321, the IDG is located at 5 O’clock position. In CFM56-7B installed on Boeing 737-800, IDG is located at 8 O’clock position.

48.     What are the units of torque and momentum?

Ans: Unit of torque is lbs.-inch and unit of momentum is Kgms-1.

49.     What are consumable and expandable?

Ans: Consumable are those which cannot be re-used such as hydraulic fluid, lubricating oil etc.
Expandable are those whose life can be extended such as gasket, rubber type materials etc.

50.     What is ATA chapter 27, 32, 33, 75, 80?

Ans: ATA chapters
27   Flight controls
32      Landing gear
33      Lights
75   Air
80   Starting

51.     How will you ask for Philips screwdriver at store?

Ans: I will ask for Philips screwdriver mentioning its point number.

52.     How will you ask for torque wrench at store?

Ans: I will ask for torque wrench at the store by mentioning type and torque range.

53.     What is ATA? Why it is called so?

Ans: ATA is Air Transport Association.
It is an association that manages and standardize the various publications related to aircraft operation and maintenance and hence it is called ATA.

54.     What is IPC?

Ans: IPC or Illustrated Parts Catalogue is a document that includes detailed exploded view of every component and contain table of all parts, materials and hardware present in the respective component mentioning part numbers of each and number of such items present.

55.     Where will you find torque value?

Ans: The torque value can be known from the AMM or task card.

56.     What is the difference between dipstick and tripstick?

Ans: Refer to Q. No. 15

57.     What is the difference between FADEC and EEC?

Ans: Refer to Q. No. 10

58.     Location of EEC.

Ans: In CFM56-5B installed in Airbus A321, EEC is located at 4 O’clock position while in CFM56-7B installed on Boeing 737-800, EEC is located at 2 O’clock position.

59.     Units of pressure.

Ans: Pressure is measured in either Pounds per Square Inch (PSI), inches of Mercury (inch Hg), mm of Mercury (mm Hg), Pascal (Pa) or milibar (mbar).

60.     How wire cutters are classified?

Ans: Wire cutters are classified by the design of its head.

61.     What are the differences between igniter plug and spark plug?

Ans: Igniter plugs are used in gas turbine engines where spark is required only during initial engine start or during an in-flight engine re-light condition. However, spark plugs are used with reciprocating engine and produces sparks at regular intervals throughout the time of operation of the engine.
The gap between centre electrode and ground electrode is more in case of an igniter plug while it is comparatively small for spark plug.
The spark intensity of an igniter plug is more than a spark plug.
Due to higher spark intensity, igniter plugs are less susceptible to carbon or lead deposit in its electrode ends. However, carbon or lead fouling are often encountered in spark plugs.

62.     Diameter of Philips screwdriver is given in what terms?

Ans: The diameter of Philips screwdriver is given in points.

63.     Specific gravity?

Ans: Specific gravity is the ratio of density of a certain volume of a substance to the density of equal volume of pure water in case of liquid and air in case of gas. Both densities are measured at 4OC.

64.     How mallets are classified?

Ans: Mallets are classified according to the material of which it is head is made of.

65.     What is the standard fuelling pressure?

Ans: The standard fuelling pressure is 50 psi.

66.     If you are given

Actual torque = 120 in-lbs. Lever length = 12 in.
Extension = 3 inch
Then what will be the indicated torque at the torque wrench?
π΄π‘π‘‘π‘’π‘Žπ‘™ π‘‘π‘œπ‘Ÿπ‘žπ‘’π‘’ ×πΏπ‘’π‘£π‘’π‘Ÿ π‘™π‘’π‘›π‘”π‘‘β„Ž

Ans: Indicated torque on the wrench =

πΏπ‘’π‘£π‘’π‘Ÿ π‘™π‘’π‘›π‘”π‘‘β„Ž+𝐸π‘₯π‘‘π‘’π‘›π‘ π‘–π‘œπ‘›
120 × 12
12 + 3

= 96

67.     Tell us about Fly-By-Wire technology.

Ans: In Fly-By-Wire equipped airplane, pilot’s commands are converted into electrical signals which are supplied to the servo valves that re-directs the hydraulic pressure accordingly to operate various flight controls and mechanisms such as landing gear, thrust reversers etc.
The advantages of Fly-By-Wire aircraft are
a.         Weight reduction
b.        Gust load elevation
c.         Flight envelope protection etc.
However, Fly-By-Wire aircraft system also have some disadvantages such as
a.                      Complexity of airplane increases.
b.                     Unit cost increases.
c.                      Failure of one component may cause entire system breakdown.

68.     What is Air Speed and Ground Speed? What is the difference between them?

Ans: Air speed is the speed of an object relative to air.
Ground speed is the speed of the object relative to ground or earth.
If air is calm, i.e. there is no wind, then airspeed and ground speed are equal. However, if there is wind which means the air will have some velocity relative to earth. Thus it effects the ground speed however doesn’t affect the air speed.

69.     What is the difference between igniter plug and spark plug?

Ans: Refer to question number 61.

70.     What do you mean by stability of aircraft?

Ans: Stability of aircraft is defined as the ability of the aircraft to maintain a straight and level flight without any assistance from the cockpit. The stability may be either around longitudinal axis, lateral axis or vertical axis.

71.     What is the relation between density and pressure and volume? How does it affects air at high altitudes?

Ans: The density varies proportionally to pressure and inversely to volume. In other words, as density decreases, pressure decreases while as density decreases, volume increases.
The higher above the earth’s surface we go, the thinner the air becomes. Thus density at high altitude is less than that of at sea level and hence the pressure decreases as we go higher and higher above ground.

72.     1 kg = ? pounds

Ans: 1 kg = 2.2 pounds

73.     Running torque.

Ans: Running torque is the torque value to keep a load moving.

74.     What is flat rating of engine?

Ans: Flat rating is provided by many engine manufacturer. It is the rated thrust which the engine is capable of producing up to an ambient temperature of 90OF.

75.     What is cascade effect?

Ans: The effect on air flowing through one stage of compressor by the succeeding stage due to the cascading arrangement of aerofoils in each stage is called cascade effect.

76.     What is the difference between moment and torque?

Ans: Basically looking, moment and torque are the same thing. However, there is a little bit of difference.
Torque is basically a force acting on an object such as to cause or tend to cause it to rotate or twist around a definite point which we term as either pivot or fulcrum or axis. However, the application of torque may cause a turning effect on the object and this turning effect is termed as moment.
Mathematical expression of moment is equal to the force multiplied by the perpendicular distance from the pivot point. The mathematical expression of torque is equal to the force multiplied by the perpendicular distance between the two opposite forces acting on the body that causes it to rotate.

Q:   What is the difference between Airbus A321 and Boeing 737?

A:   The difference is that A321 is a fly-by-wire equipped airplane while Boeing 737 is a conventional flight controlled equipped airplane.

Q:   What do you mean by conventional flight control?

A:   Conventional flight control is where flight control systems are connected with cables and related mechanical devices like bell cranks, push-pull rods etc.

Q:   If CSD is not getting proper drive, what will happen?

A:   Output will fluctuate.

Q:   How we can disengage IDG? Under what condition, disengagement is performed?

A:   IDG is disengaged with the help of two guarded switches in the cockpit Electrical panel.
IDG is disengaged when the following conditions occur:
a.          Oil overheat.
b.          Oil pressure drop.

Q:   Where will you find the fuel specific gravity?

A:   From the fuelling chart which is available with the bouser personnel.

Q:   What is the meaning of the triangle in the fire bottle?

A:   Triangle indicates class A fire compatibility.
Note: Square indicate class B, Circle indicates class C and Star indicates class D fire.

Q:   How IDG gets drive?

A:   IDG is driven by the accessory gear box.

Q:   Why ‘No Smoking’ placarding is done near re-fuelling zone?

A: When tanks are re-fuelled, air comes out of vent ports which contains fuel vapour or fumes. They can easily catch fire if exposed to heat or spark. Therefore ‘No Smoking’ is displayed near fuelling zone.

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