Entrained water.  Water suspended in jet fuel. The amount  of entrained water that can be held in the fuel is determined  by the temperature of the fuel. When the fuel becomes cold,  the water precipitates out and forms ice crystals on the fuel  filter element. EICAS.  Engine indicating and crew alerting system. An  electronic instrumentation system that monitors airframe and  engine parameters and displays the essential information on a  video display on the instrument panel. Only vital information  is continually displayed, but when any sensed parameters  fall outside of their allowable range of operation, they are  automatically displayed. Epicyclic reduction gears.  A gear train in which a series  of small planetary gears rotate around a central gear. More  commonly called a planetary gear train. Elastic limit.  The maximum amount of tensile load, in  pounds per square inch, that a material is able to withstand  without permanent deformation. EPR.  Engine pressure ratio. The ratio of the turbine discharge  total pressure to the compressor inlet total pressure. EPR is  normally used as the parameter to determine the amount of  thrust an axial-flow turbojet or turbofan engine is producing. Electrical potential.  The electrical force caused by a  deficiency of electrons in one location and an excess of  electrons in another. Electrical potential is measured in volts. Electrical steel.  A low-carbon iron alloy that contains some  silicon It is used as the core for transformers, field frames  for generators and alternators, and the magnetic circuit of  magnetos. ESHP.  Equivalent shaft horsepower. A measure of the  power produced by a turboprop engine. ESHP takes  into consideration both the shaft horsepower delivered  to the propeller and the thrust developed at the engine  exhaust. Under static conditions, one shaft horsepower is  approximately equal to 2.5 pounds of thrust. Ethanol.  Alcohol made from cereal grains such as corn. Ether.  A volatile, highly flammable liquid that may be used  to prime the cylinders of an aircraft engine when starting  under extremely cold conditions. Electromagnet.  A magnet produced by an electrical current  flowing through a coil of wire. The coil is normally wound  around a core of soft iron which has an extremely low  retentivity, allowing it to lose its magnetism as soon as the  current stops flowing. Ethylene dibromide.  A colorless, poisonous liquid  BrCH$_{2}$CH$_{2}$Br that is blended with leaded gasoline to help  scavenge lead oxides. Electromagnetic radiation.  A method of transmitting energy  from one location to another. Current caused by high voltage  in the secondary winding of a magneto produces electric  and magnetic fields which oscillate back and forth at a high  frequency and extend out into space in the form of waves.  These waves of electromagnetic radiation are received as  interference by the radio receivers in the aircraft. Ethylene glycol.  A form of alcohol used as a coolant for  liquid-cooled aircraft engines. It is also used in automobile  engines as a permanent antifreeze. Eutectic.  An alloy or solution that has the lowest possible  constant melting point. Evaporative cooling.  See steam cooling. Electromotive force.  A force that causes electrons to move  from one atom to another within an electrical circuit. An  electromotive force, or EMF, is the difference in the electrical  pressure, or potential, that exists between two points. An  EMF may be produced by converting mechanical movement,  pressure, chemical, light, or heat energy into electrical  energy. The basic unit of EMF is the volt. Exceedance condition.  A condition in which a parameter  sensed by the EICAS exceeds the limits for which it is  programmed. Emulsion.  A suspension of small globules of one material  in another when the two materials will not mix. Oil and  water will not mix, but they can be formed into an emulsion.  An emulsion will separate into its components when it is  allowed to sit. Exhaust cone.  The fixed conical fairing centered in the  turbine wheel. The exhaust cone straightens the flow and  prevents the hot gases from circulating over the rear face of  the turbine wheel. Engine trimming.  A maintenance procedure in which the  fuel control on a gas turbine engine is adjusted to cause the  engine to produce the required EGT or EPR at a specified rpm. Exhaust nozzle.  The opening at the rear of the exhaust pipe. G-11