Annunciator panel.  A panel of warning lights in plain sight  of the pilot. These lights are identified by the name of the  system they represent and are usually covered with colored  lenses to show the meaning of the condition they announce. Anodizing.  The electrolytic process in which a hard, airtight,  oxide film is deposited on aluminum alloy for corrosion  protection. Antenna.  A special device used with electronic  communication and navigation systems to radiate and receive  electromagnetic energy. Anti-ice system.  A system that prevents the formation of ice  on an aircraft structure. Anti-icing additive.  A chemical added to the turbine-engine  fuel used in some aircraft. This additive mixes with water that  condenses from the fuel and lowers its freezing temperature  so it will not freeze and block the fuel filters. It also acts as  a biocidal agent and prevents the formation of microbial  contamination in the tanks. Antidrag wire.  A structural wire inside a Pratt truss airplane  wing between the spars. Antidrag wires run from the rear spar  inboard, to the front spar at the next bay outboard. Antidrag  wires oppose the forces that try to pull the wing forward. Antiservo tab.  A tab installed on the trailing edge of a  stabilator to make it less sensitive. The tab automatically  moves in the same direction as the stabilator to produce an  aerodynamic force that tries to bring the surface back to a  streamline position. This tab is also called an antibalance tab. Antiskid brake system.  An electrohydraulic system in an  airplane’s power brake system that senses the deceleration rate  of every main landing gear wheel. If any wheel decelerates  too rapidly, indicating an impending skid, pressure to that  brake is released and the wheel stops decelerating. Pressure  is then reapplied at a slightly lower value. Antitear strip.  Strips of aircraft fabric laid under the  reinforcing tape before the fabric is stitched to an aircraft wing. Arbor press.  A press with either a mechanically or  hydraulically operated ram used in a maintenance shop for  a variety of pressing functions. Arcing.  Sparking between a commutator and brush or  between switch contacts that is caused by induced current  when a circuit is broken. Area.  The number of square units in a surface.  Aspect ratio.  The ratio of the length, or span, of an airplane  wing to its width, or chord. For a nonrectangular wing, the  aspect ratio is found by dividing the square of the span of the  wing by its area. Aspect Ratio = span$^{2}$ ÷ area. Asymmetrical airfoil.  An airfoil section that is not the same  on both sides of the chord line. Asymmetrical lift.  A condition of uneven lift produced by  the rotor when a helicopter is in forward flight. Asymmetrical  lift is caused by the difference between the airspeed of the  advancing blade and that of the retreating blade. Attenuate.  To weaken, or lessen the intensity of, an activity. Attitude indicator.  A gyroscopic flight instrument that gives  the pilot an indication of the attitude of the aircraft relative to  its pitch and roll axes. The attitude indicator in an autopilot  is in the sensing system that detects deviation from a level- flight attitude. Augmenter tube.  A long, stainless steel tube around the  discharge of the exhaust pipes of a reciprocating engine.  Exhaust gases flow through the augmenter tube and produce  a low pressure that pulls additional cooling air through the  engine compartment. Heat may be taken from the augmenter  tubes and directed through the leading edges of the wings  for thermal anti-icing. Autoclave.  A pressure vessel inside of which air can be  heated to a high temperature and pressure raised to a high  value. Autoclaves are used in the composite manufacturing  industry to apply heat and pressure for curing resins. Autogyro.  A heavier-than-air rotor-wing aircraft sustained  in the air by rotors turned by aerodynamic forces rather than  by engine power. When the name Autogyro is spelled with  a capital A, it refers to a specific series of machines built by  Juan de la Cierva or his successors. Autoignition system.  A system on a turbine engine that  automatically energizes the igniters to provide a relight if  the engine should flame out. Automatic adjuster.  A subsystem in an aircraft disk brake  that compensates for disk or lining wear. Each time the brakes  are applied, the automatic adjuster is reset for zero clearance,  and when the brakes are released, the clearance between the  disks or the disk and lining is returned to a preset value. A  malfunctioning automatic adjuster in a multiple-disk brake  can cause sluggish and jerky operation. G-3