frontal 102
mixed area between air masses of dif-ferent temperatures or densities
frontal /frnt(.)l/ adjective 1. refer-ring to the forward part or surface area of something . the frontal area . fron-tal surface the boundary between two air masses 2. of or relating to a meteor-ological weather front . a frontal storm

frontal depression /frnt(.)l d.
pre.(.)n/ noun an area of low pressure found together with a weather front
frontal system /frnt(.)l s.st.m/
noun a series of rain-bearing changes in the weather
frost /fr.st/ noun a deposit of very small ice crystals formed when water vapour condenses at a temperature below freezing . Frost had to be cleared from training aircraft which had been parked outside overnight. . hoar
ft /fυt/ abbreviation foot
fuel /fju.l/ noun a substance such as gas, oil, petrol, etc., which is burnt to produce heat or power . Each wing tank holds 20 gallons of fuel. . A fuel system includes tanks, fuel lines, fuel pumps, fuel filters and a carburettor or fuel injection system.

fuel/air mixture /fju.l e.
m.kst../ noun a combination of fuel and air which is ignited in a piston engine to provide power
COMMENT: Aircraft engines operate at different altitudes and the pilot must adjust the mixture to produce the most efficient fuel/air mixture for the atmospheric density.

fuel gauge /fju.l e.d/ noun an
instrument indicating fuel contents
fuel injection /fju.l .ndek.(.)n/, fuel injection system noun system in which fuel is sprayed under pressure into the combustion chamber of an engine
fuel injector /fju.l .ndekt./
noun an injector that sprays fuel into the combustion chamber of an engine
fuel pump /fju.l pmp/ noun a
device which moves fuel along pipes
from the tanks to the engine fumes /fjumz/ plural noun smoke, gas or vapour given off by a substance, often unpleasant or harmful . When the cabin is rapidly and completely filled by smoke and fumes, passengers will suffer from disorientation.
function /f.k..n/ noun 1. a spe-cific occupation or role . Rota planning is one of the functions of the chief instructor. 2. purpose . Seals perform a very important function in a hydraulic system. . The function of the flaps is to increase lift and drag. . verb 1. to act as, or to serve the purpose of . The escape slide also functions as a life raft.
2. to operate or to work . The system functions well.
fundamental /fnd.ment(.)l/ adjective 1. of or relating to the founda-tion or base . the fundamental laws of aerodynamics 2. central, forming or serving as an essential component of a system or structure . Electricity is one of the fundamental types of energy that exist in nature.

fungal growth /fn.l raυθ/
noun a type of organism which lives and multiplies in particular fuels . Fuel contains chemicals for the inhibition of fungal growth.
fuse /fjuz/ noun a safety device that protects an electric circuit from an excessive current . Circuit breakers perform the same function as a fuse.