INLET GUIDE VANES (IGVs)--The
HELIX-- (1) A tube or solid material
variable vanes ahead of the first stage of
(gear teeth) wrapped like threads on a screw.
compressor blades of a GTE. Their function is
(2) Anything having a spiral shape. (Math-
to guide the inlet air into the GTE compressor at
ematically, a helix is the shape of the curve formed
the optimum angle.
on any cylinder by a straight line in a plane that
is wrapped around the cylinder, such as an
INLET PLENUM--That section for the GTE
ordinary screw thread.)
inlet air passage that is contained within the engine
enclosure.
HERTZ (Hz)--A unit of frequency equal to
one cycle per second.
INTEGRATED THROTTLE CONTROL
HIGH-PRESSURE (HP) AIR SYSTEM--A
(ITC)--The ITC has control electronics located
in the PACC that allow single lever control of
system that is designed for a nominal operating
throttle and pitch of one shaft. Two levers (one
pressure in excess of 1000 psig.
per shaft) are located at the SCC and at the PACC
on the DD and CG class ships.
HYDRAULIC--Conveyed, operated, or
moved by water or other liquid in motion.
INTERLOCK--A device that prevents an
action from taking place until all required
HYDRAULIC ACTUATOR--A device that
conditions are met.
converts hydraulic pressure to mechanical
movement.
JP-5--The principal use of JP-5 is fuel for
helicopters and small boats.
HYDRAULIC OIL POWER MODULE
(HOPM)-- The HOPM is located near the MRG.
KELVIN SCALE--A thermometric scale on
It delivers pressure-regulated oil to the power oil
which the units are the same size as the Celsius
piping and the control oil piping.
scale with the zero point shifted to absolute zero.
Absolute zero on the Celsius scale is -273.15.
HYDROMETER-- An instrument used to
measure specific gravity. In batteries hydrometers
KILOWATT-- A unit of electrical power
are used to indicate the state of charge by the
equal to 1,000 watts. (A watt is a unit of power
specific gravity of the electrolyte.
equal to the rate of work represented by a
current of 1 ampere under a pressure of 1 volt.)
HYDROSTATIC-- Related to liquids at rest
or the pressures they exert or transmit.
KINETIC ENERGY--Energy in motion.
HYSTERESIS-- The inability of an elastic
LABYRINTH/HONEYCOMB SEALS--
member to return to its original position after it
This type of seal combines a rotating element and
has been stressed. To lag.
a honeycomb stationary element to form an air
seal. Used in gas turbines to maintain close
INDUCTION (ELECTRICAL)--The process
tolerances over a large temperature range.
by which (1) an electrical conductor becomes
electrified when near a charged body, (2) a
LABYRINTH/WINDBACK SEALS--This
magnetizable body becomes magnetized when in
type of seal combines a rotating element with a
a magnetic field, or (3) an electromotive force
smooth surface stationary element to form an oil
(emf) is produced in a circuit by varying the
seal. This type of seal is used with an air seal with
magnetic field linked with the circuit.
a pressurization air cavity between the two seals.
Pressure in the pressurization air cavity is always
INERT GAS--A gas that has no active
greater than the sump pressure. Therefore, flow
chemical properties.
across the seal is toward the sump. This prevents
oil leakage from the sump. The windback is a
INFORMATION CONTROL CONSOLE
coarse thread on the rotating element of the oil
(ICC)--The ICC is part of the ECU. The ICC
seal which uses screw action (windback) to force
No. 1 is the panel used to program and run the
any oil that might leak across the seal back into
computer. The ICC No. 2 is the tape reader used
the sump.
to input the program into the ECU.
AI-7
