Aviation Maintenance Terms beginning with A
A/D
Analog/Digital; Analog-to-Digital
A/D CONV
Analog-to-Digital Converter
A/FD
Airport/Facility Directory
A/L
Autoland
AC
Alternating current. Electrical current in which the electrons continually change their rate of flow and periodically reverse their direction.
AC
Advisory Circular
AC
Advisory Circular
ac
Alternating Current
AC
Advisory Circular (FAA)
ACARS
ARINC Communication Addressing and Reporting System
ACC
Active clearance control. A system for controlling the clearance between tips of the compressor and turbine blades and the case of high-performance turbofan engines. When the engine is operating at maximum power, the blade tip clearance should be minimum, and the ACC system sprays cool fan discharge air over the outside of the engine case. This causes the case to shrink enough to decrease the tip clearance. For flight conditions that do not require such close clearance, the cooling air is turned off, and the case expands to its normal dimensions. The control of the ACC system is done by the FADEC, or full-authority digital electronic control.
ACO
Aircraft Certification Office
ACO
Aircraft Certification Office
ACR
ADS-B Aircraft Operation Compliance Report
AD
Airworthiness Directive
AD (ashless dispersant) oil
A mineral-based lubricating oil used in reciprocating engines. This oil does not contain any metallic ash-forming additives, but has additives that disperse the contaminants and hold them in suspension until they can be removed by filters.
ADC
Air data computer. An electronic computer in an aircraft that senses pitot pressure, static pressure, and total air temperature. It produces an indication of altitude, indicated airspeed, true airspeed, and Mach number. The output of ADC is usable by any of the engine or flight control computers.
ADC
Air-Sata Computer
ADC
Air data computer.
ADCP
ATC Dual-control Panel
ADEDS
Advanced Electronic Display System
ADF
Automatic Direction Finder
ADF
Automatic direction finder.
ADI
Attitude-director Indicator; Air Data Instrument
ADI
Attitude director indicator.
ADI (antidetonation injection) system
A system used with some large reciprocating engines in which a mixture of water and alcohol is sprayed into the engine with the fuel when operating at extremely high power. The air/fuel mixture is leaned to allow the engine to develop its maximum power, and the ADI fluid absorbs excessive heat when it vaporizes.
ADIRS
Air Data And Inertial Reference System
ADS-B
Automatic Dependent Surveillance - Broadcast
ADS-B
Automatic Dependent Surveillance – Broadcast
ADS-B IN
Receipt, processing, and display of other aircraft’s ADS-B transmissions. ADS-B IN is necessary to use airborne applications.
ADS-B In- Receipt
Processing, and display of other aircraft’s ADS-B transmissions. ADS-B In is necessary to utilize airborne applications.
ADS-B OUT
Transmission of an aircraft’s position, altitude, velocity, and other information to other aircraft and ATC ground-based surveillance systems.
ADS-B Out
Transmission of an aircraft’s position, altitude, velocity, and other information to other aircraft and ATC ground based surveillance systems.
ADS-R
Automatic Dependent Surveillance - Rebroadcast
ADS-R
Automatic Dependent Surveillance – Rebroadcast
AFC
Automatic Frequency Control
AFCS
Automatic Flight Control System
AFDS
Autopilot Flight Director System
AFM
Airplane Flight Manual
AFM
Airplane flight manual.
AFM
Aircraft Flight Manual
AFMS
Airplane Flight Manual Supplement
AIM
Aeronautical Information Manual
AIRB
Basic Airborne
AIRCOM
Air/Ground Communications
AM
Amplitude Modulation
AML
Approved Model List
AMP
Amperes
AMP or AMPL
Amplifier
AMS
Aerospace Material Specification
AN
Army/Navy
AND
Army Navy Design
ANSI
American National Standards Institute
ANSP
Air Navigation Service Provider
ANT
Antenna
AP
Autopilot
APB
Auxiliary Power Breaker
APC
Absolute pressure controller.
APCU
Auxiliary Power Control Unit
APU
Auxiliary power unit. A small turbine- or reciprocating- engine-powered generator, hydraulic pump, and air pump. APUs are installed in the aircraft and are used to supply electrical power, air, and hydraulic pressure when the main engines are not running.
APU
Auxiliary power unit.
APU
Auxiliary Power Unit
ARINC
Aeronautical Radio Incorporated
ARNC IO
ARINC I/O Error
ARNC STP
ARINC I/O UART Data Strip Error
ARP
Aerospace Recommended Practice
ASA
Aircraft Surveillance Applications
ASAS
Aircraft Surveillance Applications System
ASDE-X
Airport Surface Detection Equipment, Model X
ASSAP
Airborne Surveillance and Separation Assurance Processing
ASTC
Amended Supplemental Type Certificate
ASTM
American Society For Testing Materials
ATA
Air Transport Association
ATAS
ADS-B Traffic Advisory System
ATC
Air Traffic Control
ATC
Air Traffic Control
ATC
Air Traffic Control
ATCRBS
Air Traffic Control Radar Beacon System
ATCRBS
Air Traffic Control Radar Beacon System
ATCT
ATC Transponder
ATCTS
ATC Transponder System
ATF
Aerodynamic twisting force. The aerodynamic force that acts on a rotating propeller blade to increase its blade angle. The axis of rotation of a blade is near the center of its chordline, and the center of pressure is between the axis and the leading edge. Aerodynamic lift acting through the center of pressure tries to rotate the blade to a higher pitch angle.
ATS
Air Traffic Services
AUX
Auxiliary
AVC
Automatic Volume Control
AWG
American Wire Gauge
AWS
Air Weather Service
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