Avionics - Fly by Wire Flight Control Quiz(MCQ)

1 .

Why is the BFW system used?

A)

Better navigation

B)

For communications in aircraft

C)

Reduced chances of enemy detection

D)

To control aerodynamically efficient but unstable body

Correct Answer : To control aerodynamically efficient but unstable body

Explanation : The literal meaning of Fly By wire system is flying by wires(I.e; electrically). One of the main advantages of using FBW is to exploit increased aerodynamic shapes at the cost of stability. The FBW system provides high integrity automatic stabilization to compensate for the loss of stability and provide overall better performance.

2 .

How is fly by wire system implemented in an aircraft?

A)

By using computers and actuators to control surfaces

B)

Artificial intelligence

C)

By using high power radio transmitters and receivers

D)

By using control rods and linkages connecting stick to control surfaces

Correct Answer : By using computers and actuators to control surfaces

Explanation : The fly by wire system uses actuators to move the control surfaces to maintain the stability of an aircraft. The signals sent by the pilot via the control stick is intercepted by the flight controller computer and signals are sent to the respective actuators to move the control surfaces.

3 .

What type of system is classified as "Direct electric link system"?

A)

System with serial wire connection

B)

System with motion sensor feedback

C)

System without motion sensor feedback

D)

Systems with parallel wire connection

Correct Answer : System without motion sensor feedback

Explanation : A FBW system by definition has to have a motion feedback system. Without these, the system is considered as “Direct electric system”. The information from these sensors is used to automatically stabilize the aircraft.

4 .

What does FBW use to scale the control surface deflection according to the aircraft's airspeed and height?

A)

Autopilot system

B)

Air Data Computer

C)

Flight Control Computer

D)

Flight Management System

Correct Answer : Air Data Computer

Explanation : FBW uses an Air Data System to scale the control surface deflection according to the aircraft’s airspeed and height variations. The need for air data information on the airspeed and height is to compensate for the very wide variation in the control surface effectiveness over the aircraft’s flight envelope of height and speed combinations. The Air Data Computer provides various information available from the airstream such as airspeed, altitude, and angle of attack.

5 .

What is the incidence angle in the yaw plane called?

A)

Yaw angle

B)

Crossflow angle

C)

Side slip angle

D)

Angle of crosswind

Correct Answer : Side slip angle

Explanation : The angle of incidence in the yaw plane is known as the side slip angle. It is the angle between the direction the aircraft is travelling and the direction its nose is pointing. When the side slip angle is high the aircraft is not in a coordinated turn and hence is flying inefficiently.

6 .

Why does an FBW system use a smaller tail area?

A)

To reduce weight and drag but at a cost of natural stability

B)

Bigger tails are harder to move as they produce larger wing loads

C)

Actively controls the tail thus making up for the reduced stability due to lesser area

D)

Tail does not contribute much to stability and its area can thus be reduced effectively

Correct Answer : To reduce weight and drag but at a cost of natural stability

Explanation : The reason for using reduced tail area is to reduce weight, drag and to increase overall performance, But at a cost of reduced natural stability. A FBW makes up for the reduced stability by actively controlling the tailplane and rudder using accurate motion feedback sensors and actuators.

7 .

Which one of the following is not true with respect to the FBW system?

A)

FBW makes an aircraft stealthy

B)

FBW is not necessary for every aircraft

C)

FBW provides better control and carefree flying

D)

FBW makes aircraft with low stability fly smoothly

Correct Answer : FBW makes an aircraft stealthy

Explanation : The FBW system need not necessarily provide stealth to an aircraft. It provides control, stability and carefree flying in aircraft with low natural stability. Typically stealthy aircraft design is mainly focused on stealth and has very less stability, here FBW provides good handling and control characteristics to fly the aircraft without FBW system.

8 .

An aircraft is negatively stable when ______

A)

it is flying inverted

B)

its tailplane does not produce lift

C)

its tailplane produces negative lift (downwards)

D)

its tailplane produces positive lift (upwards)

Correct Answer : its tailplane produces positive lift (upwards)

Explanation : An aircraft is said to be negatively stable when its tailplane produces positive lift. The tail of an aircraft without an FBW system must always produce negative lift to maintain stability and to keep the nose up. Since it produces negative lift, it actually acts in the direction of weight reducing aerodynamic efficiency. In an FBW equipped aircraft a positive lift producing tail can be used by using flight control computers and motion sensors to main stability at all times.

9 .

Which of the following is not a component of the FBW system?

A)

Actuators

B)

Communication receivers

C)

Flight control computer

D)

Aircraft motion sensor

Correct Answer : Communication receivers

Explanation : The fly by wire system consists of control stick (input by the pilot), Flight control computer(processing unit), actuator control electronics(signal to actuators), actuator(movement of control surfaces). Communication systems are completely independent of FBW systems.

10 .

FBW system requires an air data system for control and stability.

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : The air data system provides various information like airspeed, height(density of air), angle of attack and temperature. These parameters change with flight and are considered necessary to maintain optimal control and stability at all times.

11 .

How are FBW signals transmitted?

A)

Duplex

B)

Simplex

C)

Time division multiplexing

D)

Code division multiplexing

Correct Answer : Time division multiplexing

Explanation : Transmission of electric signals is a key element in a FBW system. Faster the signal transmission, quicker the response of the aircraft to the pilot stick controls. Time division multiplexing is used where signals can be transmitted along a network comprising only of two wires as only one set of data is being transmitted at any particular time.

12 .

Which one of the following is a military standard data bus?

A)

ARINC 429

B)

Mil Std 1553

C)

ARINC 629

D)

COMAC C919

Correct Answer : Mil Std 1553

Explanation : Mil Std 1553 is a US military standard data bus which came out in the 1970s in the F-16 and the following models of fighter aircraft. It has a data rate of 1Mbit/sec and a word length of 20 bits to encode clock, data, and address and so can receive or transmit up to 50,000 data words a second.

13 .

Why is FBW essential in stealth aircraft?

A)

Improves control

B)

Reduces engine noise

C)

FBW system damps radar energy

D)

Disturbs tracking techniques used by missiles

Correct Answer : Improves control

Explanation : Stealth configurations and requirements can conflict with aerodynamics requirements and FBW flight control is essential to give acceptable control and safe handling across the flight envelope. An example of such is the American fighter F -117, nicknamed “Nighthawk”. It is almost impossible to fly this aircraft without feedback FBW system.

14 .

Fill the missing block in the roll rate command system.

A)

Display

B)

Autopilot

C)

Flight control computer

D)

Rate gyro

Correct Answer : Rate gyro

Explaination : The missing block is in a feedback loop, typically it consists of a motion sensor. Here the motion sensor used is a rate gyro. The signal from the rate gyro is subtracted from pilot’s input so that the error in deflection is corrected.

15 .

What is the relation between autopilot and FBW?

A)

Autopilot is not related to FBW

B)

Autopilot is a part of FBW system

C)

FBW provides autopilot commands for roll, pitch, and yaw

D)

Autopilot provides FBW commands of roll, pitch, and yaw

Correct Answer : Autopilot provides FBW commands of roll, pitch, and yaw

Explanation : The autopilot is like an artificial pilot system which flies the aircraft under a set of constraints. It provides steering commands such as roll, pitch and yaw rates to the FBW system. FBW system ensures that response to the autopilot commands is fast and well damped, providing smooth control of aircraft in autopilot modes.

16 .

A FBW control stick is referred as _______

A)

FBW joystick

B)

FBW control pad

C)

FBW inceptor

D)

FBW analog stick

Correct Answer : FBW inceptor

Explanation : A FBW control stick is referred to as FBW inceptor. An inceptor by definition is a device that converts the pilot’s control inputs into electrical signals. There are two types of inceptors- active and passive.

17 .

Why are dampers an essential element in FBW inceptors?

A)

Provides accurate deflections

B)

Acts as a low pass filter on the stick movement

C)

Control aircraft stability by damping forces

D)

To prevent aircraft to carry out critical maneuvers

Correct Answer : Acts as a low pass filter on the stick movement

Explanation : Without the damper, the stick would be considerably under damped because of the low friction in the mechanism and the significant mass of the hand grip. It provides a smooth feel to the stick movement; the spring–mass–damper combination acting as a low pass filter on the stick movement. These characteristics are carefully tailored to meet the consensus of pilot approval.

18 .

In a typical quadruplex actuator system, how is the failure of an actuator identified?

A)

Using reflectometry

B)

Using in-lane fault detection

C)

By comparing it with a simulation model

D)

By comparing it with the signal of the three good ones

Correct Answer : By comparing it with the signal of the three good ones

Explanation : A typical quadruplex system uses signal processing based FDI( Fault Detection and Isolation) system. It identifies the failed actuator by comparing its control signal with the other three good ones. A model-based FDI system is generally used in triplex architecture.

19 .

The reason for using quadruplex actuation system is _______

A)

as a fail safe mechanism

B)

precise movement

C)

quick reaction to the control stick movement

D)

to counteract heavy air loads on the control surfaces

Correct Answer : as a fail safe mechanism

Explanation : A quadruplex actuation system consists of four independent actuators whose output drives the power control unit. The fail-safe mechanism of the quadruplex system is that when one fails three can override it. All four actuators have totally independent power and control electronics.

20 .

What type of cable is used in ARINC 629?

A)

Coaxial cable

B)

Parallel lines

C)

Screened twisted pair

D)

Unscreened twisted pair

Correct Answer : Unscreened twisted pair

Explanation : The ARINC 629 links and bus uses an unscreened twisted pair of wires with a connection to the bus through demountable current transformer couplers. Mil STD 1553 uses screened twisted pair cables. Parallel lines are rarely used today.

21 .

Why are both electrical and hydraulic systems are used in the same aircraft?

A)

Quick deflections

B)

To generate more force

C)

As a fail safe

D)

Hydraulics for more force and electric for quick deflections

Correct Answer : As a fail safe

Explanation : Most of the main actuators are electro-hydraulic, fully electric actuators are used as a fail safe for hydraulic actuators. They must be able to survive any two failures and carry on operating satisfactorily in order to meet the aircraft safety and integrity requirements.

22 .

Why are actuators used in FBW systems?

A)

Increase lift

B)

Movement of control surfaces

C)

Reduce drag

D)

Safety equipment

Correct Answer : Movement of control surfaces

Explanation : Unlike traditional aircraft, FBW system uses electrical signals to operate the actuators which in turn move the control surface in place of mechanical linkages and control rods directly connecting the pilot’s stick to the control surfaces.

23 .

What are control laws?

A)

Laws that govern flight motion

B)

Algorithms relating pilots stick and control surface

C)

Laws that govern aerodynamics forces

D)

Laws used to predict range and endurance

Correct Answer : Algorithms relating pilots stick and control surface

Explanation : The term ‘control laws’ is used to define the algorithms relating the control surface demand to the pilot’s stick command and the various motion sensor signals and the aircraft height, speed and Mach number.

24 .

Flight control systems comes under the category of _______

A)

SISO

B)

SIMO

C)

MIMO

D)

MISO

Correct Answer : MIMO

Explanation : Flight control systems come into the category of multi-input/multi-output (MIMO) closed-loop control systems as control is exerted about three axes and there are six degrees of freedom. The classic control theory approach is very suitable for single input/single output (SISO) closed-loop control systems and some single input/multi-output (SIMO) systems.

25 .

What is PIO?

A)

Pilot induced oscillations

B)

Pitot indicator

C)

Primary Input/Output

D)

Pressure indicator observed

Correct Answer : Pilot induced oscillations

26 .

What can occur when the control valve travel limits are reached under conditions of large amplitude demands?

A)

Stall

B)

Rate delimiting

C)

Structural damage

D)

Rate limiting

Correct Answer : Rate limiting

Explanation : Rate limiting can occur when the control valve travel limits are reached under conditions of large amplitude demands. The behaviour under rate limiting conditions is non-linear and the onset and the effects are dependent on the amplitude and frequency of the input demand.

27 .

What happens to the phase lag in an actuator as the frequency is increased?

A)

Increases

B)

Constant

C)

Decreases

D)

Cannot be determined

Correct Answer : Increases

Explanation : The response of the actuators at low frequencies is basically that of a low pass (or first-order) filter, but as the frequency increases the lags in the first stage actuation system become dominant. The output/input ratio falls at an increasing rate and the phase lag rapidly increases.

28 .

What is θi in pitch rate command law?

A)

Gain in loop

B)

Pitch rate gearing

C)

Tailplane demand angle

D)

Pilot input angle

Correct Answer : Pilot input angle

Explaination : Pitch rate command law is given by

ηD = K(θi − Gqq)

where ηD is the tailplane demand angle; θi is the pilot’s input command; q is the pitch rate; K is the forward loop gain, and Gq is the pitch rate gearing.

29 .

What is false true with respect to K in the pitch rate command law?

A)

Value of K is infinite

B)

Value of K changes with height and altitude

C)

Value of k is constant with altitude and airspeed

D)

Value of K is constant with height and altitude

Correct Answer : Value of k is constant with altitude and airspeed

Explanation : As the altitude and airspeed are varied, the magnitude of hinge moment in the control surface varies. This raises the need to vary gain K with change in flight conditions.

30 .

Derivative of a control system provides _______

A)

Infinite gain

B)

Reduced overshoot

C)

Low steady state error

D)

Gain proportional to error

Correct Answer : Reduced overshoot

Explanation : Derivative of error control provides a phase advance characteristic to compensate for the lags in the system, for instance, actuator response, and hence improve the loop stability. This increases the damping of the aircraft response and reduces the overshoot to a minimum when responding to an input or disturbance.

31 .

What is the angle of incidence limiting?

A)

The minimum angle of attack that can be measured

B)

Warning indication to the pilot during high angles of incidence

C)

Reducing the error that occurs in an angle of incidence indicator

D)

Keeping angle of incidence under safety limits whilst maneuvering

Correct Answer : Keeping angle of incidence under safety limits whilst maneuvering

Explanation : The incidence terms from the airstream sensors can be blended with the pitch rate error terms and the ‘gearings’ (or gain coefficients) of these terms adjusted as higher angles of attack are approached. This enables the angle of incidence to be kept within the safe limits whilst maneuvering at high angles of incidence, i.e., the angle of incidence limiting.

32 .

What are the shortcomings of using an angle of incidence indicator for feedback sensor?

A)

Works only in subsonic ranges

B)

Ground and impact damage from landing

C)

Damage from bird strikes and local airflow disturbance

D)

Damage from ice formation and local airflow disturbance

Correct Answer : Damage from bird strikes and local airflow disturbance

Explanation : Although the angle of incidence indicator can provide motion feedback sensor information the major shortcomings of using them are damage from bird strike as they are mounted external to an aircraft and effect of the local airflow around the fuselage cause variations in measured values.

33 .

What is the MTBF of a solid state rate gyro?

A)

1,000 to 5,000 hrs

B)

5,000 to 10,000 hrs

C)

10,000 to 50,000 hrs

D)

50,000 to 100,000 hrs

Correct Answer : 50,000 to 100,000 hrs

Explanation : Solid state rate gyros are very reliable sensors with an MTBF in the region of 50,000 to 100,000 hours – ‘fit and forget’ devices. Also, they are mounted internally and suffer less damage from the environment.

34 .

Integral of a control system provides ____

A)

Low steady state error

B)

infinite gain

C)

Reduced overshoot

D)

Gain proportional to error

Correct Answer : Low steady state error

Explanation : Integral of error control eliminates steady-state errors and reduces the following lag. The integral of error term increases the loop gain at low frequencies up to theoretically infinite gain at dc so that there are zero steady-state errors due to out of trim external moments or forces acting on the aircraft.

35 .

Phase advance control is also known as _________

A)

Integral error controller

B)

One plus derivative error controller

C)

Derivative error controller

D)

Proportional error controller

Correct Answer : One plus derivative error controller

Explanation : A phase advance controller is usually known as phase advance controller with a transfer function.
The control term is filtered to limit the increase in gain at high frequencies and smooth the differentiation process which amplifies any noise present in the error signal.

36 .

What is the failure probability figure of a commercial aircraft?

A)

1×10^-6/hr

B)

1×10^-11/hr

C)

1×10^-20/hr

D)

1×10^-28/hr

Correct Answer : 1×10^-6/hr

Explaination : The statistical level of safety currently being achieved with civil aircraft transport corresponds to a figure of around 1 × 10^-6/hour. This figure is derived from the total number of civil aircraft crashes occurring in a year from all causes divided by the total number of aircraft flying and their annual operating hours.

37 .

What is MTBF?

A)

Mean Time Before Fracture

B)

Minimum Time Between Failures

C)

Mean Time Between Failures

D)

Maximum Time Between Failures

Correct Answer : Mean Time Between Failures

Explanation : MTBF is abbreviated as Mean Time Between Failures. It is the predicted time between two inherent failures of a system. The mean time between failures, or MTBF, of a single channel FBW system is in the region of 3,000 hours. The FBW system must thus possess redundancy with multiple parallel channels so that it is able to survive at least two failures if these very low failure probability figures are to be met.

38 .

What is called a quadruplex system?

A)

System with 4 channels

B)

System with 8 channels

C)

ystem with 4 times the speed

D)

System which does not fail

Correct Answer : System with 4 channels

Explanation : A well established redundant system comprises four totally independent channels of sensors and computers in a parallel arrangement to give the required failure survival capability – such a configuration is referred to as a quadruplex system.

39 .

Which of the following is not a common mode failure?

A)

Bird strike

B)

Lightning strike

C)

Incorrect maintenance

D)

Fire/explosion/battle damage

Correct Answer : Bird strike

Explanation : The type of failure which can affect all systems at the same time is termed a Common Mode Failure. Examples of common mode failures are the Lightning strike, Electro-magnetic interference, Fire/explosion/battle damage, Incorrect maintenance, Common design errors – e.g., software.

40 .

How is failure detected in a quadruplex system?

A)

Adding signals

B)

Monitoring signals

C)

Subtracting signals

D)

Cross comparing signals and voting

Correct Answer : Cross comparing signals and voting

Explanation : Failure signals are detected by cross comparison and majority voting. In a quadruplex system, every channel cross compares every other channel to detect a failure in its own channel. For example, if three channel has signal ‘x’ and one has signal ‘y’, the majority signal is voted as good and the channel with signal ‘y’ is disconnected.

41 .

What are C 1, C 2, C 3, C 4 in the following diagram of the quadruplex system?

avionics

A)

Monitor

B)

Computer

C)

Blank box

D)

Power control unit

Correct Answer : Computer

Explaination : The signal from the lane passes through the voter and consolidator for cross comparison of signals. These signals are then passed on to the computer which applies control laws and calculates the amount of deflection required by the actuator. The signal passes through another set of voter and consolidator for errors before passing to on to the actuator.

42 .

What type of system does the figure represent?
avionics

A)

Duplex system

B)

Monitored system

C)

Monitored duplex system

D)

Monitored diplex system

Correct Answer : Monitored duplex system

Explaination : A monitored system uses signal monitors to identify error in the signal. If an error is identified the main signal is disconnected and the next channel takes over. Since there are two channels in the above system it is a monitored duplex system.

43 .

Complete the signal flow diagram for a monitored system

avionics

A)

Monitor

B)

Lane

C)

Error compensator

D)

Flight control computer

Correct Answer : Monitor

Explaination : The signal lane is the main channel carrying the signal. It is monitored by a monitor which checks the signal. If the signal is incorrect it is disconnected and the next channel takes over.

44 .

In a quadruplex system, when does a passive fail situation occur?

A)

When all the channels fail

B)

When 2 channels fail none is disconnected

C)

When 1 channel fail none is disconnected

D)

When 3 channels fail and none is disconnected

Correct Answer : When 2 channels fail none is disconnected

Explanation : When two channels fail and are not disconnected, two good channels versus two failed hard over channels so that the control surface does not move resulting in a ‘fail passive’ situation. When one channel fails and is not disconnected, the other three good channels overrides the failed one.

45 .

Which of the following uses a monitoring system to check the function of channels?

A)

Major triplex

B)

Master triplex

C)

Matching triplex

D)

Monitored triplex

Correct Answer : Monitored triplex

Explanation : The incorporation of a monitoring system to check the correct functioning of a channel to a very high confidence level can also enable a failed channel to be identified and disconnected and this leads to an alternative failure survival configuration known as ‘monitored triplex’. A monitored triplex configuration comprises three totally independent parallel channels with each channel monitored by a dissimilar system to detect a failure.

46 .

Which of the following is not a result of digital implementation?

A)

Flexibility in updating

B)

More power

C)

Built in test capabilities

D)

Hardware economy

Correct Answer : More power

Explanation : The digital implementation in FBW only affects the control and stability of the aircraft. Power is not, in any way, related to the FBW system.

47 .

What is it called when the sampled signal is of lower frequency than the original signal?

A)

Aliasing

B)

Damping

C)

Overshoot

D)

Steady state error

Correct Answer : Aliasing

Explanation : When the sampled signal is of lower frequency than the original signal it is known as aliasing. Aliasing induces data loss and errors. It can be reduced by a process called anti-aliasing.

48 .

Which of the following is true with respect to the passive optical sensor?

A)

Not affected by EMI

B)

Does not require an electrical supply

C)

Output from the sensor is an optical signal

D)

Processing this signal does not require any electrical device

Correct Answer : Processing this signal does not require any electrical device

Explanation : Passive optical sensors offers particular advantages as these sensors are not affected by EMI. Passive optical sensors are defined as sensors which do not require electrical supplies or any electronic processing at the sensor, the output of the sensor being an optical signal which is modulated by the quantity being measured. The processing of this optical signal is carried out by a separate electronic unit which is fully screened from EMI, the only connection between the sensor and the electronic unit being an optical fibre cable.

49 .

What happens when the output of one channel is delayed by one iteration period before comparing with other channels in a quadruplex system?

A)

Aliasing

B)

Latency

C)

Staleness

D)

High noise

Correct Answer : Staleness

Explanation : Data staleness occurs when a channel is delayed by, say, one iteration, before comparison with others. To overcome this problem it is necessary to have some form of time synchronisation of the computer iteration periods.

50 .

How is aliasing prevented?

A)

Sampling at the same frequency of the original signal

B)

Sampling at double the frequency of the original signal

C)

Sampling at more than double the frequency of the original signal

D)

Sampling at less than double the frequency of the original signal

Correct Answer : Sampling at more than double the frequency of the original signal

Explanation : Aliasing occurs when the sampling rate is lower than the frequency of the original signal. The Nyquist theorem states that the sampling rate should be more than twice the frequency of the original signal to avoid aliasing.

51 .

Which of the following is not an advantage of using a digital data bus?

A)

Self test

B)

Less weight

C)

Multiplexing

D)

Not affected by electromagnetic interference

Correct Answer : Not affected by electromagnetic interference

Explanation : Very large reductions in the weight of cabling are achieved by the use of multiplexed data transmission and data bus networks. High integrity data transmission can be achieved with very comprehensive self checking and data validation capabilities. However, they are heavily affected by electromagnetic interference.

52 .

How is data staleness overcome?

A)

Up conversion

B)

Time synchronisation

C)

Down conversion

D)

Using multiple channels

Correct Answer : Time synchronisation

Explanation : Data staleness problem it is necessary to have some form of time synchronisation of the computer iteration periods. This iteration period synchronisation is generally implemented through software.

53 .

Which of the following affects the Fly-By-Wire system?

A)

EMI

B)

Bad weather

C)

Lightning strikes

D)

Flying in powerful Radio/Radar region

Correct Answer : Bad weather

Explanation : One of the common modes of failure in the Fly-By-Wire system is EMI. Since the whole aircraft runs on electricity, Electromagnetic Interference heavily affects the FBW system. It is caused by lightning strikes and in regions of high power radio or radar.

54 .

What is EMP?

A)

Electromagnetic pulse

B)

Electromagnetic Power

C)

Electromagnetic protection

D)

Electrically Matched power line

Correct Answer : Electromagnetic pulse

Explanation : An EMP, abbreviated as Electromagnetic pulse is a sudden change in the magnitude of an electrical field(a pulse) with strengths of hundreds of volts per meter. It occurs in a very wide range of electromagnetic radiation spectrum and can damage any electrical equipment in its vicinity.

55 .

What is EMC?

A)

Electromagnetic capture

B)

Electromagnetic course

C)

Electromagnetic combat

D)

Electromagnetic compatibility

Correct Answer : Electromagnetic compatibility

Explanation : EMC or Electromagnetic compatibility is the ability of the aircraft equipment to withstand high levels of EMI. This is a necessary condition as many cases have occurred of aircraft experiencing severe transients in the automatic flight control system placing the aircraft temporarily out of control whilst overflying high power radar/radio transmitters. This has been due to the susceptibility of the flight control system analogue electronics to EMI because of inadequate electro-magnetic screening.

56 .

What is nuclear hardness?

A)

Ability to defend nuclear weapons

B)

Ability to survive a nuclear explosion

C)

Ability to survive in the vicinity of nuclear explosion

D)

Ability to drop nuclear weapons with precision

Correct Answer : Ability to survive in the vicinity of nuclear explosion

Explanation : Vicinity to a nuclear explosion and consequent emission of gamma radiation and an EMP of very high electric field strength. Military avionic equipment is specially designed to survive up to a certain (classified) level of these effects. This attribute is referred to as ‘nuclear hardness’ and is achieved by the design of the circuits, use of nuclear hard components, circumvention techniques and very efficient electromagnetic screening.

57 .

Where is an EMC vault used?

A)

Shield for wires

B)

Housing of all electronics

C)

Housing of FBW computer

D)

Screened enclosure around the connector

Correct Answer : Screened enclosure around the connector

Explanation : The wires from the cable connectors and the EM filters are housed within a screened enclosure around the connector known as an ‘EMC vault’ so that there is no aperture for EMI radiation to enter the box. The wires connecting different electrical equipment are the most affected by EMI.

58 .

Where was the first Fly-By-Light system used?

A)

Spacecrafts

B)

Airships

C)

Fighter aircraft

D)

Bomber Aircraft

Correct Answer : Airships

Explanation : Non-rigid airships may be acquiring a new lease of life as long duration platforms for airborne radar surveillance systems. The airship is able to carry a large high power radar antenna within its envelope and is able to remain airborne for several days. Since the antenna could severely interfere with FBW systems FBL system was used.

59 .

What type of multiplexing is used in optical fiber lines?

A)

Time division multiplexing

B)

wavelength division multiplexing

C)

Code division multiplexing

D)

Frequency division multiplexing

Correct Answer : wavelength division multiplexing

Explanation : Fibre optic data transmission use ‘wavelength division’ multiplexing whereby a single fibre can be used to transmit several channels of information as coded light pulses of different wavelengths (or colours) simultaneously. The individual data channels are then recovered from the optically mixed data by passing the light signal through wavelength selective passive optical filters which are tuned to the respective wavelengths. WDM has a very high integrity as the multiplexed channels are effectively optically isolated.

60 .

Which one of the following is false with respect to fiber optic cables?

A)

Costly

B)

High speed

C)

Less EM interference

D)

Heavy compared to normal wires

Correct Answer : Heavy compared to normal wires

Explanation : Fiber optics weigh comparatively very low than normal wires. Wires require shielding from EMI which also adds up to the overall weight of the connectivity system. They also offer high speed data transfer and are relatively costly.