5. Digital techniques / Electronic instrument systems - Q&A

Two connected fibre optic cable ends are parallel but not quite touching. This is called

• end to end coupling.
• butt joint coupling.
• lateral gap coupling.

In a CRT, if the magnetic field is parallel to the Y plates, what will be the direction of the electron beam movement?

• Diagonal.
• Vertical.
• Reversed.

Before removing an assembly from an aircraft, with regards to HIRF, you must first ensure that there is minimum current flow between

• you and the airframe.
• you and the assembly.
• you and the aircraft.

An 8 data input multiplexer has how many Data Select lines?

• 8.
• 3.
• 2.

A BITE check for automatic performance and fault monitoring is carried out when?

• Power-up self test.
• On engine shutdown.
• During flight mode.

In a single mode fibreoptic cable

• several light wave modes can propagate simultaneously through the cable.
• the diameter of the cable is dependent on the wavelength of the light used.
• the distortion of the signal is determined by the total length of cable used.

When testing EGT probe

• it must be soaked and ambient temperature allowance taken into consideration.
• not necessarily soaked but ambient temperature must be taken into consideration.
• if not soaked, the standard ambient temperature of 15 degrees C is assumed.

ARINC 629 is

• half duplex.
• full duplex.
• single mode.

The control of the speed or rate that the flight director command bars move can be controlled by

• variable gain adjustment.
• rate or velocity feedback.
• proportional gain factor.

To deflect the beam of a CRT horizontally, coils are placed on the neck of the tube

• left and right.
• top and bottom.
• diagonally opposite.

ACARS is an acronym for

• Airframe Communicating Addressing and Reporting System.
• Airborne Communicating Addressing and Reporting System.
• Aircraft Communicating Addressing and Reporting System.

If part of a display is lost on a CRT, this could be due to

• an inoperative symbol generator or control panel.
• an inoperative symbol generator or input sensor.
• an inoperative EFIS control panel or data bus.

Fly By Wire systems in the fully active mode, the actuators will

• both be active.
• one be standby.
• both be damped.

ACARS is an acronym for

• Airframe Communicating Addressing and Reporting System.
• Airborne Communicating Addressing and Reporting System.
• Aircraft Communicating Addressing and Reporting System.

Electronic Centralised Aircraft Monitoring System

• show green and white advisory messages to display system health.
• give blue and white caution messages to display system faults.
• give red warnings and amber cautions to display system status.

The T/R of ARINC 629 is

• Encoder / decoder unit.
• Multiplex / demultiplex.
• Analog / digital convert.

In fibreoptic cable, signals are separated by

• active optic filter.
• optic signal amplifier.
• passive optic filter.

Common aircraft fibreoptics use

• modulating intensity on direct read.
• modulating frequency on direct read.
• modulating phase on direct read.

The arithmetic logic unit (ALU) in a central processor unit (CPU) carries out

• addition, subtraction, multiplication and division.
• data storage, retrieval, and logical comparisons.
• timing, synchronisation, and bus control operations.

If on a flight deck EFIS system all the displays were missing one bit of information. This is most likely to be

• the input sensor bus and display controller.
• the input sensor bus and display processor.
• the display controller and symbol generator.

Before fitting a Printed Circuit Board you should check the

• resistance between skin and strap end plug is less than 10 megohms.
• resistance between skin and strap end plug is more than 1 megohms.
• resistance between strap and strap end plug is less than 1 megohms.

In a MU, how is parallel converted to serial?

• By way of a shift register.
• By way of a data latch unit.
• By way of a demultiplexer.

What is the advantage of an ILD over an LED when used as a light source in fibre optics?

• Lower frequency range.
• Greater power output.
• Wider frequency output.

ACARS is an acronym for

• Airframe Communicating Addressing and Reporting System.
• Airborne Communicating Addressing and Reporting System.
• Aircraft Communicating Addressing and Reporting System.

A Digital to Analogue Converter has a resolution of 0.3 Volts. What will be the analogue output when the digital input is 10110

• 6.6 Volts AC.
• 3.3 Volts DC.
• 6.6 Volts DC.