Part-66 Module 5 flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

EFIS symbol generator

Computer in an electronic flight instrument system that converts sensor and navigation data into display symbology and drives the display units; normally duplicated to provide redundancy.

EICAS

Engine indication and crew alerting system used on Boeing aircraft, displaying engine parameters and system warning, caution and advisory messages on the flight deck.

Display colour convention

Red indicates a warning, amber a caution, green a normal or active condition, cyan an advisory and white the labels and scales, on most electronic instrument systems.

Two's complement

Method of representing signed binary numbers by inverting all bits and adding one; an n-bit two's complement number ranges from minus 2^(n-1) to plus 2^(n-1) minus one.

BCD encoding

Binary coded decimal represents each decimal digit separately as four bits in the 8421 code, so the pattern is not the pure binary value of the whole number.

Gray code

A binary code in which only one bit changes between consecutive values, preventing ambiguous readings from position encoders and similar sensors.

ARINC 429

Simplex serial data bus carrying a 32-bit word with an 8-bit label, source/destination identifier, data, sign/status matrix and parity, at 12.5 or 100 kbit/s over a twisted pair.

MIL-STD-1553B

Military standard command/response multiplex data bus operating at 1 Mbit/s with one bus controller and up to 31 remote terminals.

ARINC 629

Bi-directional avionics data bus using time-division multiplexing and operating at 2 Mbit/s; it was introduced on the Boeing 777.

De Morgan's theorem

The complement of a product equals the sum of the complements, and the complement of a sum equals the product of the complements; used to simplify logic expressions.

XOR gate

Exclusive-OR gate whose output is logic 1 when its inputs differ and 0 when they are equal; used for parity generation and the sum output of a half adder.

D flip-flop

Sequential logic element that stores and outputs the value present on its data input at the active clock edge; used in registers and shift registers.

ALU

Arithmetic logic unit inside the central processor that performs arithmetic operations such as addition and logic operations such as AND, OR and comparison.

Address bus

Unidirectional bus carrying the memory or input/output address from the processor; an address bus of n lines can select 2^n separate locations.

Flash memory

Non-volatile semiconductor memory that is electrically erased in blocks and rewritten, used for stored software and non-volatile configuration data in aircraft computers.

CMOS versus TTL

CMOS uses field-effect transistors with very low static power, wide supply range and high noise immunity but is static-sensitive; TTL is bipolar, normally 5 V, faster and draws more current.

Pin 1 identification

On a dual-in-line or similar package, pin 1 is marked by a notch or a dot, and the remaining pins are counted anticlockwise viewed from the top.

Fan-out

The maximum number of logic gate inputs that a single gate output can drive while voltage levels remain within the specified logic limits.

Nyquist criterion

To reconstruct a signal without aliasing, the sampling frequency must be at least twice the highest frequency contained in the sampled signal.

Time-division multiplexing

Multiplexing in which each channel is allocated a recurrent time slot on a single link, so several signals share one transmission path.

Wavelength-division multiplexing

Optical multiplexing in which several signals at different wavelengths are combined and carried simultaneously through a single optical fibre.

Total internal reflection

Light passing from a denser core to a less dense cladding is reflected back into the core when the angle of incidence exceeds the critical angle, guiding light along the fibre.

Single-mode fibre

Fibre with a very small core, about 9 micrometres, supporting one propagation path; it gives low dispersion and long-distance capability when used with a laser source.

Graded-index fibre

Multimode fibre whose core refractive index decreases towards the cladding, progressively bending rays and reducing modal dispersion compared with step-index fibre.

LCD backlight

Liquid crystal displays do not emit light; a cold-cathode fluorescent or LED backlight illuminates the panel through polarisers, liquid crystal cells and colour filters.

TFT active matrix

Liquid crystal display construction in which every pixel has its own thin-film transistor, improving contrast, response time and freedom from cross-talk.

ESD wrist strap

Strap worn on the wrist and connected to ground through a resistor of about one megohm, which bleeds static charge away safely without risk of electric shock.

DO-178C

Certification standard for airborne software that defines objectives and assurance levels A to E according to the consequence of software failure, level A being catastrophic.

HIRF

High-intensity radiated fields from sources such as radars and broadcast transmitters; aircraft systems must be shown to tolerate specified field strengths.

Twisted pair wiring

Two conductors twisted together so that induced interference tends to cancel; used for data buses and low-level signals to reduce electromagnetic coupling.

BITE

Built-in test equipment within an aircraft system that monitors operation, detects faults, stores fault codes and supports maintenance interrogation of the system.

TCAS II

Traffic alert and collision avoidance system that displays intruder traffic and issues coordinated resolution advisories, such as climb or descend, to equipped aircraft.