Part-66 Module 5 study guide
Part-66 Module 5 · Work through your exam, one topic at a time.
EASA Part-66 Module 5 - Digital Techniques / Electronic Instrument Systems - is one of the required knowledge modules in the aircraft maintenance licence (AML) syllabus for categories B1 and B2, and it is also widely used as a stand-alone digital-avionics fundamentals course. It is aimed at trainee and practising aircraft maintenance engineers, avionics technicians and students on Part-147 programmes who need to understand how modern aircraft generate, process, transport and display data. The Part-66 Module 5 study guide has 12 sections and about 3,768 words.
01Electronic Instrument Systems
Glass cockpits replaced mechanical gauges with a chain of computers and displays, and questions usually test whether you know where each signal is generated and which unit owns which function. Air data comes from pitot and static probes processed by an air data computer (ADC); attitude, heading and acceleration come from an inertial reference system (IRS) or attitude and heading reference system (AHRS).
364 words, about 2 min02Numbering Systems and Data Conversion
Each digit is multiplied by the base raised to its position. Binary is base 2, octal base 8, hexadecimal base 16.
323 words, about 2 min03Data Buses
A 32-bit word on a twisted shielded pair: 8-bit label (quoted in octal), 2-bit source/destination identifier, 19 data bits, 2-bit sign/status matrix and 1 parity bit (odd). One transmitter only, up to 20 receivers, simplex, at 12.5 kbit/s (low speed) or 100 kbit/s (high speed).
327 words, about 2 min04Logic Circuits
Learn the truth tables for AND, OR, NOT, NAND, NOR, XOR and XNOR, and be able to read a symbol as an equation. NAND and NOR are universal: any function can be built from either alone.
321 words, about 2 min05Basic Computer Structure and Microprocessors
A microprocessor contains the arithmetic logic unit, the control unit and registers. Von Neumann machines share one memory for data and instructions; Harvard machines use separate paths, allowing instruction fetch and data access simultaneously.
324 words, about 2 min06Integrated Circuits
Integration runs from SSI (a few gates) through MSI and LSI to VLSI (millions of devices). TTL uses bipolar transistors: fast, current-hungry, traditionally a 5 V supply.
299 words, about 1 min07Multiplexing
Multiplexing lets many signals share one medium. A multiplexer selects one of 2^n inputs using n select lines; a demultiplexer routes the result back to the right output.
317 words, about 2 min08Fibre Optics
Light is guided by total internal reflection in a core of higher refractive index surrounded by cladding. Single-mode fibre has a core of about 9 micrometres and carries one path, allowing long distances at 1310 or 1550 nm with a laser source.
326 words, about 2 min09Electronic Displays
A CRT fires an electron beam at a phosphor screen, requiring deflection coils, a high-voltage supply of several kilovolts and leaded glass for shielding; phosphor persistence affects smear. LCDs are non-emissive: they modulate light from a backlight using polarisers and liquid crystals, with thin-film transistors forming an active matrix that improves contrast and response.
287 words, about 1 min10Electrostatic Sensitive Devices and Software Management Control
Walking across a synthetic floor can charge a body to several kilovolts. Discharge through a semiconductor junction can vaporise tracks (catastrophic damage) or degrade the device so that it fails later (latent damage).
302 words, about 2 min11Electromagnetic Environment
Interference reaches a victim by radiation through space, by conduction along wires, or by capacitive and inductive coupling between adjacent conductors; common-impedance coupling through a shared ground return is another path. Sources include motors, relays, switching regulators, digital clocks, transmitters and static discharge.
278 words, about 1 min12Typical Electronic/Digital Aircraft Systems
The flight management system holds the navigation database, flight plan and performance data and supplies guidance to the autopilot and autothrottle. Air data computers and inertial reference units feed the electronic flight instrument system and the flight director.
300 words, about 2 min