Appendix 1 Intergranular corrosion — The formation of corrosion along the grain boundaries within a metal alloy.
Interlocked-grained wood — Wood in which the fibers are inclined in one direction in a number of rings of annual growth, then gradually reverse and are inclined in an opposite direction in succeeding growth rings, then reverse again.
Inverter — A device for converting direct current to alternating current.
Laminate — A product obtained by bonding two or more laminae of the same material or of different materials.
Laminated wood — A piece of wood built up of plies or laminations that have been joined either with glue or with mechanical fastenings. The term is most frequently applied where the plies are too thick to be classified as veneer and when the grain of all plies is parallel.
Leakage field — The magnetic field forced out into the air by the distortion of the field within a part, caused by the presence of a discontinuity or change in section configuration.
Linter — The short fiber left on the cotton seed after ginning.
Localizer — That section of an ILS that produces the directional reference beam.
LORAN (long-range navigation) — A radio navigation system utilizing master and slave stations transmitting timed pulses. The time difference in reception of pulses from several stations establishes a hyperbolic line of position that may be identified on a LORAN chart. By utilizing signals from two pairs of stations, a fix in position is obtained.
-M through O- Magnetic field — The space around a source of magnetic flux in which the effects of magnetism can be determined.
Marker beacon — A radio navigation aid used in an instrument approach to identify distance to the runway. As the aircraft crosses over the marker-beacon transmitter, the pilot receives an accurate indication of the airplane’s distance from the runway through the medium of a flashing light and an aural signal.
Master switch — A switch designed to control all electric power to all circuits in a system.
Moisture content of wood — Weight of the water contained in the wood usually expressed in percentage of the weight of the kiln-dry wood.
Multiconductor cable — Consists of two or more cables or wires, all of which are encased in an outer covering composed of synthetic rubber, fabric, or other material.
Nick — A sharp notch-like displacement of metal surface.
Appendix 1 Nomex braid — NOMEX is the trade name for a high-temperature polyamide thread that is braided over the larger sizes (# 8 gage and larger) of many of the military specification wires. It can be encountered in either an off-white or black/green color.
Normalizing — Reforming of the grain structure of a metal or alloy by proper heat treatment to relieve internal stresses.
Open circuit — An incomplete or broken electrical circuit.
Open-grained wood — Common classification of painters for woods with large pores, such as oak, ash, chestnut, and walnut. Also known as “coarse-textured.”
Operational check — This is an operational test to determine whether a system or component is functioning properly in all aspects in conformance with minimum acceptable manufacture design specifications.
Optical fiber — Any filament or fiber made of dielectric materials that guides light whether or not it is used to transmit signals.
Orifice — Opening through which gas or air flows. It is usually the final opening controlled by a valve.
Oxidizing — Combining oxygen with any other substance. For example, a metal is oxidized when the metal is burned, i.e., oxygen is combined with all the metal or parts of it.
Oxidizing flame —An oxy-fuel gas flame having an oxidizing effect due to excess oxygen.
Oxygen cutting — Cutting metal using the oxygen jet which is added to an oxygen-acetylene flame.
Oxygen regulator — Manually-adjustable device used to reduce cylinder pressure to torch pressure and to keep the pressure constant. They are never to be used as fuel gas regulators.
-P- Peel ply — A layer of resin-free material used to protect a laminate for later secondary bonding (sometimes referred to as a release film).
Pickling — The treatment of a metal surface by an acid to remove surface corrosion.
Pitch — Is the distance, in inches, that a propeller section will move forward in one revolution, or the distance a nut will advance in one revolution of the screw in a single thread.
Pitch distribution — Is the gradual twist in the propeller blade from shank to tip.
Pitted — Small irregular shaped cavities in the surface of the parent material usually caused by corrosion, chipping, or heavy electrical discharge.
Pitting — The formation of pockets of corrosion products on the surface of a metal.
Appendix 1 Plastic — An organic substance of large molecular weight which is solid in its finished state and, at some stage during its manufacture or its processing into a finished article, can be shaped by flow.
Polyester braid — A plastic braiding thread, when used as the outer surface of a wire, provides a cloth-like appearance.
Polyimide tape — A plastic film (commonly referred to by the trade name, KAPTON). The tape has a dark brown color, and is frequently coated with a polyimide varnish that has a very distinct mustard yellow color. At times, the spiral edge of the outermost tape is apparent under the varnish topcoat. It may be used for wire insulation. Total polyimide tape insulated wire constructions are inactive for new design on military aircraft and are subject to the procedures defined in FAA Advisory Circular (AC) 29-2, Certification of Normal Category Rotorcraft, Paragraph 29.1359, in civil aircraft.
Polyimide varnish — A liquid form of polyimide that is applied to the outer surface of a wire through the process of repeated dipping through the varnish bath with subsequent heat curing.
The successive layers rarely reach a total buildup of 1 mil.
Polymerization — Basic processes for making large (high-polymer) molecules from small ones, normally without chemical change; can be by addition, condensation, rearrangement, or other methods.
Porosity — Cavity-type discontinuities in metal formed by gas entrapment during solidification.
Prepreg — A mat, a fabric, or covering impregnated with resin that is ready for lay up and curing.
Propeller — Is a rotating airfoil that consists of two or more blades attached to a central hub which is mounted on the engine crankshaft.
Protractor — Is a device for measuring angles.
PTFE Tape (Insulation) — Polytetrafluoroethylene tape (commonly known by the trade name, TEFLON), wrapped around a conductor and then centered with heat, fusing the layers into a virtually homogeneous mass. It is used both as a primary insulation against the conductor, and as an outer layer or jacket over a shield. Maximum temperature rating is 260 °C.
PVF2 Polyvinylidine Fluoride — A fluorocarbon plastic, that when used in aircraft wire, is invariably radiation cross-linked and employed as the outer layer.
-R- Radar (radio detecting and ranging) — Radio equipment that utilizes reflected pulse signals to locate and determine the distance to any reflecting object within its range.
Radome — A nonmetallic cover used to protect the antenna assembly of a radar system.
Appendix 1 Rectifier — A device for converting alternating current to direct current.
Reinforcing tape — A narrow woven cotton or polyester tape used over aircraft fabric to reinforce it at the stitching attachments.
Relay — An electrically-operated remote-control switch.
Resin — Vast profusion of natural and increasingly, synthetic materials used as adhesives, fillers, binders and for insulation.
Resistance — The opposition a device or material offers to the flow or current.
Resonance method (ringing) of ultrasonic inspection — A method of detecting material thickness or indications of internal damage by injecting variable frequency ultrasonic energy into a material. A specific frequency of energy will produce the clearest indication of damage in a given thickness of material. When the equipment is calibrated for a specific thickness, and this thickness changes, an aural or visual alert is given.
Resonant frequency — The frequency of a source of vibration that is exactly the same as the natural vibration frequency of the structure.
Resonate — A mechanical system is said to resonate when its natural vibration frequency is exactly the same as the frequency of the force applied. When an object resonates at a particular frequency, the amplitude in its vibration will increase immensely as that frequency is reached and will be less on either side of that frequency.
Rib — Part of primary structure, whose purpose is to maintain profile of airfoil and support fabric or thin wood covering.
-S- Sacrificial corrosion — A method of corrosion protection in which a surface is plated with a metal less noble than itself. Any corrosion will attack the plating rather than the base metal.
Sandwich construction — A structural panel concept consisting in its simplest form of two relatively thin, parallel sheets (face sheets) of structural material bonded to and separated by a relatively thick, lightweight core. High strength-to-weight ratios are obtained with sandwiched materials.
Scarf joint — A joint made by cutting away similar angular segments of two adherents and bonding the adherents with cut areas fitted together.
Score — A surface tear or break on a surface that has a depth and length ranging between a scratch and a gouge.
Scratch — A superficial small cut on a surface.
Appendix 1 Semiconductor device — Any device based on either preferred conduction through a solid in one direction, as in rectifiers; or on a variation in conduction characteristics through a partially conductive material, as in a transistor.
Severe wind and moisture problem (SWAMP) areas — Areas such as wheel wells, wing folds, and near wing flaps, and areas directly exposed to extended weather conditions are considered SWAMP areas on aircraft.
Silicone rubber — A high temperature (200 °C) plastic insulation that has a substantial silicone content.
Soldering—A group of welding processes that produces coalescence of materials by heating them to the soldering temperature and by using a filler metal having a liquidus not exceeding 450 °C (840 °F) and below the solidus of the base metals. The filler metal is distributed between the closely fitted surfaces of the joint by capillary action.
Solenoid — A tubular coil for the production of a magnetic field; electromagnet with a core which is able to move in and out.
Spar — Main spanwise structural member(s) of an aircraft wing or rotorcraft rotor. A wing may have one or two made into a single strong box to which secondary leading and trailing structures are added.
Spiral grain — A type of growth in wood which the fibers take a spiral course about the bole of a tree instead of the normal vertical course. The spiral may extend right-handed or left-handed around the tree trunk.
Stator — The part of an AC generator or motor which contains the stationary winding.
Stress corrosion — Corrosion of the intergranular type that forms within metals subject to tensile stresses which tend to separate the grain boundaries.
Surface tape — Pinked-edge strips of fabric doped over all seams, rib stitching, and edges of fabric covering (also called finishing tape).
Switch — A device for opening or closing an electrical circuit.
-T- Tape — A tape or a “narrow fabric” is loosely defined as a material that ranges in width from 1/4 inch to 12 inches.
TCAS — Traffic alert and collision avoidance system. An airborne system that interrogates mode A, C, and S transponders in nearby aircraft and uses the replies to identify and display potential and predicted collision threats.
Thermocouple — Device to convert heat energy into electrical energy.
Appendix 1 Thermoplastic material — A material that can be repeatedly softened by an increase in the temperature and hardened by a decrease in the temperature with no accompanying chemical change. For example, a puddle of tar on the road in the summer during the heat of day: the tar is soft and fluid; however, when cooler in the evening, it becomes solid again.
Thermoset material — A material which becomes substantially infusible and insoluble when cured by the application of heat or by chemical means. A material that will undergo, or has undergone, a chemical reaction (different from a thermoplastics physical reaction) by the action of heat, catalysts, ultraviolet light, etc. Once the plastic becomes hard, additional heat will not change it back into a liquid as would be the case with a thermoplastic.
Tip — Part of the torch at the end where the gas burns, producing the high-temperature flame.
Transceiver — A unit serving as both a receiver and a transmitter.
Transformer — A device for raising or lowering AC voltage.
Transmitter — An electronic system designed to produce modulated RF carrier waves to be radiated by an antenna; also, an electric device used to collect quantitative information at one point and send it to a remote indicator electrically.
Transponder — An airborne receiver-transmitter designed to aid air traffic control personnel in tracking aircraft during flight.
-U through X- Unbonding — Adhesive or cohesive failure between laminates. Compare definitions of adhesive, cohesive debond, and disbond.
Very high frequency (VHF) — A frequency between 30 and 300 MHz.
VHF omnirange (VOR) — An electronic air navigation system that provides accurate direction information in relation to a certain ground station.
Videoscope — A type of borescope.
Visible light — Electromagnetic radiation that has a wavelength in the range from about 3,900 to 7,700 angstroms and that may be seen by the unaided human eye.
Visual check — Utilizing acceptable methods, techniques, and practices to determine physical condition and safety item.
Volt — Unit of potential, potential difference, or electrical pressure.
Voltage regulator — Device used in connection with generators to keep the voltage constant as load or speed is changed.
Warp — Threads in a fabric that run the length of the woven material as it comes from the mill.
Appendix 1 Watt — The unit of power; equal to a joule per second.
Wattmeter — An instrument for measuring electrical power.
Waveguide — A hollow, typically rectangular, metallic tube designed to carry electromagnetic energy at extremely high frequencies.
Wavy-grained wood — Wood in which the fibers collectively take the form of waves or undulations.
Welding — A materials-joining process used in making welds.
Welding rod — A form of welding filler metal, normally packaged in straight lengths.
Welding torch — The device used in gas welding.
Wood decay — Disintegration of wood substance through the action of wood-destroying fungi.
Wood decay – incipient — The early stage of decay in which the disintegration has not proceeded far enough to soften or otherwise perceptibly impair the hardness of the wood.
Wood decay – typical or advanced — The stage of decay in which the disintegration is readily recognized because the wood has become punky, soft and spongy, stringy, pitted, or crumbly.
X-ray — A radiographic test method used to detect internal defects in a weld.
XL-ETFE — A process of radiation cross-linking the polymer chains is used to thermally set the plastic. This prevents the material from softening and melting at elevated temperature.
XL-Polyalkene — An insulation material based on the polyolefin family that has its normally thermomelt characteristic altered by the radiation cross-linking process to that of a nonmelt, therm-set material.
Appendix 2 APPENDIX 2. ACRONYMS AND ABBREVIATIONS The acronyms and abbreviations listed are some of many that are likely to be encountered by the aviation mechanic or technician involved in the maintenance of aircraft.
429 — ARINC 429 data bus standard ARNC IO — ARINC I/O Error 629 — ARINC 629 data bus standard ARNC STP — ARNC I/O UART data strip error A/D — analog/digital; Analog-to-Digital ASTM — ASTM International A/D CONV — Analog-to-Digital Converter ATA — Air Transport Association A/L — autoland ATC — air traffic control AC — advisory circular ATCT — ATC transponder AC — alternating current ATCTS — ATC transponder system ACARS — Aircraft Communications Addressing and Reporting System AUX — auxiliary ACO — Aircraft Certification Office AVC — automatic volume control AD — Airworthiness Directive AWG — American Wire Gauge ADC — air-data computer AWS — Automatic Weather Station ADCP — ATC dual-control panel B/CU — battery/charger unit ADEDS — Advanced Electronic Display System BAT or BATT — battery ADF — automatic direction finder BCD — binary-coded decimal ADI — Attitude-Director Indicator; Air Data Instrument BIT — binary digit; Built-in Test AFC — automatic frequency control BITE — built-in test equipment AFCS — automatic flight control system BITS — bus interconnect transfer switch AFDS — Autopilot Flight Director System BNR — Binary Numerical Reference; binary AIM — Aeronautical Information Manual BP — band-pass AIRCOM — Air/ground Communications BPCU — bus power control unit AM — amplitude modulation BT — bus tie amp — amperes BTB — bus tie breaker AMP or AMPL — amplifier BTC — before top center AMS — Aerospace Material Specification BUS — electrical bus; 429 digital data bus AN — Army/Navy C.G. — center of gravity AND — Army Navy Design CAGE — commercial and government entity code ANSI — American National Standards Institute CAWS — central aural warning system;
caution and warning system ANT — antenna CB, C/B, or CKT/BKR — circuit breaker AP — autopilot CDI — course-deviation indicator APB — auxiliary power breaker CDU — central display unit APCU — auxiliary power control unit CFC — carbon fiber composite APU — auxiliary power unit CFDS — centralized fault display system ARINC — Aeronautical Radio, Inc. CAC — caution advisory computer
Appendix 2 CH or chan. — channel DISC — disconnect CHGR — charger DISTR — distribution CKT — circuit DMA — direct memory access CLK — clock DMB — dead main bus CLR — clear DMC — display management computer CMCS — central maintenance computer system DME — distance measuring equipment CMPTR — computer DMEA — distance-measuring equipment antenna CO — carbon monoxide DN — down COAX — coaxial DU — display unit COP — copper E/E or E & E — electrical/electronic CP — control panel E1-1 — first shelf, number 1 equipment rack CRT — cathode ray tube; circuit E2-2 — second shelf, number 2 equipment rack CSE or CSEU — control system electronics unit EADF — electronic automatic direction finder CSEUP — control system electronics unit panel EADI — electronic attitude director indicator CT — Computed Tomography EAROM — electrically alterable read-only memory CT — current transformer EC — EICAS computer CTN — caution ECAM — electronic centralized aircraft monitoring CU — control unit; copper EDSP — EICAS display select panel CVR — cockpit voice recorder EDU — EICAS display unit CW — continuous wave EEC — electronic engine control D/A — digital-to-analog EFI — electronic flight instrument DAC — digital-to-analog converter EFIS — electronic flight instrument system DADC — digital air-data computer EFISCP — EFIS Control Panel DBT — dead bus tie EFISCU — EFIS comparator unit dc — direct current EFISG EFIS — symbol generator DCDR — decoder EFISRLS — EFIS remote light sensor DDB — digital data bus EHSI — electronic horizontal-situation indicator DEMOD — demodulator EHSID — electronic horizontal-situation indicator display DEMUX — demultiplexer EHSV — electrohydraulic servo value DER – Designated Engineering Representative EICAS — engine indicating and crew alerting system DFDR — digital flight data recorder ELCU — electrical load control unit DG — directional gyro ELEC — electric; electronic DGTL — digital ELECT — electrical DH — decision height ELEX — electronics; electrical DISC SOL — disconnect solenoid ELT — emergency locator transmitter
Appendix 2 EMER GEN — emergency generator GND or GRD — ground EMF — electromotive force GPCU — ground power control unit EMFI — electromechanical flight instrument GPS — Global Positioning System EMI — electromagnetic interference GPSW — gear opposition switch EP — external power GPU — ground power unit EP AVAIL — external power available GPW — ground proximity warning EPC — external power contactor GPWC — ground proximity warning computer EPCS — electronic power control switch GPWS — ground proximity warning system EPROM — erasable programmable readonly memory GSR — ground service relay eV — electron volt GSSR — ground service select relay EXCTR — exciter GSTR — ground service transfer relay EXT PWR — external power GTAW — gas tungsten arc welding FAA — Federal Aviation Administration H/L — high/low FAA-PMA — Federal Aviation Administration Parts Manufacturer Approval HEA — high-frequency radio antenna FM — frequency modulation HF (hf) — high frequency (3 to 30 MHz) FM/CW — frequency modulation continuous wave HFCP — high-frequency radio control panel FMC — flight management computer HI Z — high impedance FMCD — flight management computer control display unit Hz — hertz FMCS — flight management computer systems I.D. — inner diameter FMS — flight management system I/O — input/output FOD — foreign object damage IAPS — integrated avionics processor system FREQ — frequency IAS — indicated airspeed FSEU — flap/slat electronic unit IDG — integrated drive generator FW or FWD — forward IF — intermediate frequency G/S — glide slope IFR — instrument flight rules GAL or GALY — galley IGN — ignition GCR — generator control relay auxiliary contact IIS — integrated instrument system GCU — generator control unit ILS — instrument landing system GEB — generator circuit breaker INDL — indicator light GEN — generator INST — instrument GLR — galley load relay INSTR — instrument GMAW — Gas Metal Arc Welding INTCON — interconnect GMT — Greenwich mean time; coordinated Universal time INTEC — interface GND PWR — ground power INTER — interrogation GND RET — ground return INTPH — interphone GND SVCE — ground service INV — inverter
Appendix 2 IR — ILS receiver MILLI — one-thousandth (0.001) kHz — kilohertz MKR BCN — marker beacon KSI — thousands of pounds per square inch MS — Military Standard kV — kilovolts MSDS — Material Safety Data Sheets kVA — kilovolt-amperes MSEC — (ms) milliseconds kVAR — kilovoltampere reactive MSG — message L-Band — radio frequency band (390 to 1550 MHz) MTBF — mean time between failure LCD — liquid crystal display MUX — multiplexer LD — load mV — millivolts LED — light-emitting diode NAS — National Aerospace Standard lf — low frequency (30 to 300 kHz) NAV — navigation LOZ — low impedance NC — normally closed; not connected; no connection LOC — Localizer NDB — nondirectional beacon LOX – liquid oxygen NDI — Nondestructive Inspection LRU — line replaceable unit NEG — negative LS — loudspeaker nsec (ns) — nanoseconds LSB — lower sideband NTSB — National Transportation Safety Board LSPTM — limit switch position transmitter module NVM — nonvolatile memory LT — light OAM — original aircraft manufacturer LTS — lights OBS — omni bearing selection MAC — mean aerodynamic chord OC — over-current MAN/ELEC — manual/electric OEM — Original Equipment Manufacturer MBA — marker-beacon antenna OF — over-frequency MCDP — maintenance control and display panel OVV or OV — overvoltage MCDU — multipurpose control and display unit OVVCO or OVCO — overvoltage cutout MDE — modern digital electronics P-S — parallel to series MEC — main equipment center; main engine control PA — passenger address; power amplifier meg or mega — million PARA/SER — parallel to serial MEK — methylethylketone PCU — passenger control unit; power control unit MEM — memory PMA — Parts Manufacturer Approval METO — maximum except-takeoff PMG — permanent-magnet generator MF — (mf) medium frequency (300 kHz to 3 MHz) POS — positive MHz — megahertz POT — potentiometer; plan of test MIC — microphone PR — power relay MICRO-P — microprocessor PRL — parallel MIG — Metal Inert Gas PROM — programmable read-only memory
Appendix 2 PROX — proximity SOT — start of transmission PSEU — proximity switch electronic unit SPKR — speaker psi — pounds per square inch SPR — software problem report PWR — power SQL — squelch PWR SPLY — power supply SRM – Structural Repair Manual QPL — Qualified Products List SSB — single sideband QTY — quantity SSID — Supplemental Structural Inspection Documents r-t — receiver-transmitter SSM — sign status matrix RA — radio altimeter; radio altitude ST — synchro transmitter RAD — radio STAT INV — static inverter RAIND — radio altimeter indicator STBY — standby RAM — Random-Access Memory STC — Supplemental Type Certificate RART — radio altimeter receiver-transmitter SW — switch RAT — ram air turbine SYM GEN — symbol generator RCCB — remote-control circuit breaker T-R — transformer-rectifier RCL — recall TAT — true air temperature RCVR — receiver TBDP — tie bus differential protection RCVR/XMTR — receiver/transmitter TC — type certificate RDMI — radio distance magnetic indicator TCAS — Traffic Alert and Collision Avoidance System RF (rf) — radio frequency TCDS — Type Certificate Data Sheet RFI — radio-frequency interference TDC — top dead center RLS — remote light sensor TFR — transfer RMI — radio magnetic indicator TIG — tungsten inert gas rpm — revolutions per minute TMC — thrust management computer RTV — room temperature vulcanizing TMS — Terminal Marking Sleeve SAE — SAE International TMS — thrust management system SAT — static air temperature TMSP — thrust mode select panel SATCOM — satellite communications TRU — transformer-rectifier unit SCR — silicon-controlled rectifier TSO — Technical Standard Order SDI — source destination identifier TXPDR — transponder SELCAL — selective calling system µ — micro SER DL — serial data link UBR — utility bus relay SG — symbol generator UF — under-frequency SITA — Societe International de Télécommunications Aeronautiques UHF — ultrahigh frequency (300 MHz to 3 GHz) SMAW — Shielded Metal Arc Welding UNDF — under-frequency SMD — surface mounted device UNDV — under-voltage SNR — signal-to-noise ratio US — under-speed SOL — solenoid USB (us) — upper sideband SOLV — solenoid valve µsec — microseconds SOM — start of message UV — ultraviolet