Engine Instruments Systems Oral Flashcards
In what units is the tachometer for a reciprocating engine calibrated?
In hundreds of RPM.
In what units is the tachometer for a turbine engine calibrated?
In percent of the engine’s rated takeoff RPM.
Where does the manifold pressure gage used on an aircraft reciprocating engine pick up the pressure it measures?
From the intake manifold of the engine.
What are two types of pickups used for measuring the cylinder head temperature of a reciprocating engine?
A thermocouple embedded in a gasket that is installed under the spark plug of the hottest running cylinder, or a thermocouple bayonet that is held against the cylinder head by a spring.
Why do most engine oil pressure gages have a restrictor in the line between the engine and the instrument?
The restrictor damps out pressure pulsations in the oil to keep the needle from oscillating.
What is used to measure the fuel flow of a horizontally opposed, fuel-injected reciprocating engine?
A pressure gage that measures the pressure drop across injector nozzles.
What is indicated if the needle of a ratiometer-type oil temperature indicator pegs to the high side of the dial as soon as the aircraft master switch is turned on?
There is an open in the bulb circuit that causes the instrument to see an infinite resistance. The higher the resistance in the bulb circuit, the higher the temperature indication.
What type of indicating system is used to measure the exhaust gas temperature of a turbine engine?
A set of thermocouples arranged in an averaging circuit, installed in the tail pipe of the engine.
What should a thermocouple-type cylinder head temperature indicator read when the engine is not operating?
The temperature of the outside air.
How does a torquemeter actually measure the torque produced by an engine?
Since a torquemeter is actually an oil pressure gage, the pressure it measures is produced in a torque sensor and is proportional to the amount of strain in the torsional shaft that drives the reduction gears of the turboprop engine.
What two pressures are measured to get the Engine Pressure Ratio of a turbojet engine?
The turbine discharge total pressure and the compressor inlet total pressure.
Of what two materials are the thermocouples made that are used in a turbine engine exhaust gas temperature system?
Chromel and alumel.
What kind of mechanism is normally used to measure oil pressure in a reciprocating engine?
A bourdon tube mechanism.
What is measured by the tachometers used on a two-spool gas turbine engine?
The N1 tachometer shows the RPM of the low-pressure compressor, and the N2 tachometer shows the RPM of the high-pressure compressor.
Does the tachometer of a geared reciprocating engine indicate the speed of the crank shaft or of the propeller shaft?
The speed of the crankshaft.
