Free UK CAA Part-66 Module 5 Digital Techniques/Electronic Instrument Systems — B1.1 Practice Questions

Sample Practice Questions

Try these 10 sample questions from the UK CAA Part-66 Module 5 Digital Techniques/Electronic Instrument Systems — B1.1 practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1In a conventional EFIS layout, where is the electronic horizontal situation indicator normally located relative to the electronic attitude director indicator?

   1. A.Directly above the EADI
   2. B.Directly below the EADICorrect answer: B
   3. C.On the overhead panel
   4. D.On the centre pedestal

   Explanation: The FAA handbook states, "It is almost always accompanied by an electronic horizontal situation indicator (EHSI) located just below it in the display panel." The EHSI normally sits below the EADI, preserving the familiar attitude-over-heading arrangement.

   Reference: FAA Aviation Maintenance Technician Handbook—Airframe — 10-66, Electronic Horizontal Situation Indicators

2. 2Why is binary particularly suitable for representing the state of a simple digital switch?

   1. A.Its digits represent ten voltage levels
   2. B.Its digits represent two switch statesCorrect answer: B
   3. C.Its digits represent eight timing phases
   4. D.Its digits represent sixteen addresses

   Explanation: The source states, "the two basic conditions of electricity, on and off, can be represented by the two digits of the binary number system." Two digits encode the two states; binary does not require eight, ten or sixteen physical states.

   Reference: FAA Aviation Maintenance Technician Handbook—General — 3-27, The Binary Number System

3. 3Which description distinguishes an analogue representation from a digital representation of a measured quantity?

   1. A.Analogue uses discrete steps; digital varies continuously
   2. B.Analogue is continuous; digital uses discrete valuesCorrect answer: B
   3. C.Analogue values must be positive; digital values may have either sign
   4. D.Analogue can contain noise; digital cannot be altered by noise

   Explanation: The source states, "Analog representations are continuous." Analogue representation is continuous; digital representation uses discrete values. Sign is independent of this distinction, and digital signalling is not completely immune to noise.

   Reference: FAA Aviation Maintenance Technician Handbook—Airframe — 11-3, Analog Versus Digital Electronics

4. 4An equipment-enable signal may be high only when both of two validity inputs are high. Which gate provides this basic interlock?

   1. A.OR
   2. B.XOR
   3. C.ANDCorrect answer: C
   4. D.NOR

   Explanation: The handbook states, "the output is high only when all of the inputs are high." AND requires both validity conditions. OR accepts either, XOR accepts unequal inputs, and NOR accepts neither.

   Reference: FAA Aviation Maintenance Technician Handbook—General — 12-121, The AND Gate

5. 5In computer terminology, what distinguishes software from hardware?

   1. A.Software is the physical circuitry; hardware is the instruction set
   2. B.Software is the instruction set; hardware is the physical equipmentCorrect answer: B
   3. C.Software is volatile storage; hardware is non-volatile storage
   4. D.Software is the power supply; hardware is the stored programme

   Explanation: The source states, "Hardware refers to the physical components of a computer, such as the CPU and memory. Software consists of the programs and instructions that tell the hardware what to do." The distinction concerns physical equipment versus programmes and instructions, rather than power or memory volatility.

   Reference: Lenovo—How Do Computers Work? — What is the difference between hardware and software?

6. 6In a fibre-optic data link, in what physical form is the information carried through the fibre core?

   1. A.Pressure pulses
   2. B.Light signalsCorrect answer: B
   3. C.Electrical return current
   4. D.Magnetic flux pulses

   Explanation: Corning states, "The core, or the axial part of the optical fiber, is the inner glass that carries information in the form of light signals." The optical signal travels through glass. The other options confuse optical transmission with pneumatic, electrical or magnetic transmission.

   Reference: Corning—Optical Fiber Glossary of Terms — Core and Cladding

7. 7How does the screen of a cathode-ray tube produce a visible image?

   1. A.A current through liquid crystals excites a phosphor layer
   2. B.A forward current emits light from semiconductor junctions
   3. C.An electron beam excites a phosphor coating on the screenCorrect answer: C
   4. D.A backlight shines through electrically controlled liquid crystals

   Explanation: The source states, "The inside surface of the face of the tube is treated with a phosphor material that emits light when the beam of electrons strikes it." In a CRT, the electron beam makes phosphor emit light. Semiconductor emission describes LEDs, and electrically controlled transmission describes LCDs; liquid crystals do not excite CRT phosphor.

   Reference: FAA Aviation Maintenance Technician Handbook—Airframe — Glossary, Cathode-ray tube (CRT)

8. 8Before loading aircraft software, which record helps establish the versions owned and the specific aircraft, systems and equipment to which they apply?

   1. A.The loading tool's calibration and maintenance record
   2. B.The controlled software and data configuration registerCorrect answer: B
   3. C.The supplier's catalogue of all available software releases
   4. D.The aircraft's normal and emergency electrical-load analysis

   Explanation: The source states, "a) The version of the FLS and DFLD owned; b) Which aircraft the FLS and DFLD are installed on; c) The aircraft, systems and equipment that they are only applicable to;" The controlled register ties versions to applicability and installation. Tool calibration, a catalogue and electrical-load analysis serve different purposes and do not establish the operator's software configuration.

   Reference: CAA CAP 562—Aircraft Field Loadable Software and Data — Chapter 100, Leaflet 100-10, Appendix 1, 1.1(a)–(c), p. 1

9. 9How does conductive shielding around a noisy electrical circuit help reduce radio-frequency interference?

   1. A.It raises the wanted signal voltage to overcome interference
   2. B.It guides unwanted current flows to groundCorrect answer: B
   3. C.It stores static charge so no ground connection is needed
   4. D.It replaces the circuit's separate signal-return connections

   Explanation: The source states, "the braided conductive shielding guides unwanted current flows to ground." The shield directs unwanted current to ground. It is not a signal amplifier, a charge-storage device or a substitute for the designed signal-return circuit.

   Reference: FAA Aviation Maintenance Technician Handbook—Airframe — 11-73, Reducing Radio Interference, Shielding

10. 10What is the principal role of ACARS on an airliner?

    1. A.Control the movement of primary flight-control actuators
    2. B.Provide a two-way data link with airline ground facilitiesCorrect answer: B
    3. C.Calculate aircraft attitude from inertial sensors
    4. D.Generate vertical collision-avoidance commands

    Explanation: The FAA handbook states, "ACARS is a two-way communication link between an airliner in flight and the airline’s main ground facilities." ACARS exchanges operational data with the ground. Flight-control commands, inertial attitude and collision-avoidance manoeuvres are different system functions.

    Reference: FAA Aviation Maintenance Technician Handbook—Airframe — 11-70, Aircraft Communication Addressing and Reporting System