Powerplant: D - Engine Instrument Systems

Front 1

In what units is the tachometer for a reciprocating engine calibrated?

Back 1

In hundreds of RPM.

Front 2

In what units is the tachometer for a turbine engine calibrated?

Back 2

In percent of the engine's rated takeoff RPM.

Front 3

Where does the manifold pressure gage used on an aircraft reciprocating engine pick up the pressure it measures?

Back 3

From the intake manifold of the engine.

Front 4

What are two types of pickups used for measuring the cylinder head temperature of a reciprocating engine?

Back 4

The thermocouple can be embedded in a gasket that is installed under the spark plug of the hottest running cylinder, or it can be in a bayonet that is held against the cylinder head by a spring.

Front 5

Why do most engine oil pressure gages have a restrictor in the line between the engine and the instrument?

Back 5

The restrictor damps out pressure pulsations in the oil to keep the needle from oscillating.

Front 6

What is used to measure the fuel flow of a horizontally opposed, fuel–injected reciprocating engine?

Back 6

A pressure gage that measures the pressure drop across injector nozzles.

Front 7

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?

Back 7

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.

Front 8

What type of indicating system is used to measure the exhaust gas temperature of a turbine engine?

Back 8

A set of thermocouples arranged in an averaging circuit. These thermocouples are installed in the tail pipe of the engine.

Front 9

What should a thermocouple–type cylinder head temperature indicator read when the engine is not operating?

Back 9

The temperature of the outside air.

Front 10

How does a torquemeter actually measure the torque produced by an engine?

Back 10

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.

Front 11

What two pressures are measured to get the Engine Pressure Ratio of a turbojet engine?

Back 11

The turbine discharge total pressure and the compressor inlet total pressure.

Front 12

Of what two materials are the thermocouples made that are used in a turbine engine exhaust gas temperature system?

Back 12

Chromel and alumel.

Front 13

What kind of mechanism is normally used to measure oil pressure in a reciprocating engine?

Back 13

A bourdon tube mechanism.

Front 14

What is measured by the tachometers used on a two–spool gas turbine engine?

Back 14

The N1 tachometer shows the RPM of the low–pressure compressor, and the N2 tachometer shows the RPM of the high–pressure compressor.

Front 15

Does the tachometer of a geared reciprocating engine indicate the speed of the crank shaft or of the propeller shaft?

Back 15

The speed of the crankshaft.

Front 16

What are three types of flow–indicating systems used for turbine engines?

Back 16

Vane–type, synchronous mass–type, and electronic motorless mass flow meters

Front 17

What do mass flow systems measure?

Back 17

The mass of the flow. This is affected by the density of the fuel which is in turn affected by the fuel temp.

Front 18

In what units is an electronic motorless mass flow meter system calibrated?

Back 18

Pounds per hour of fuel flow

Front 19

What is indicated in a turbine engine if the fuel flow for all condition is high?

Back 19

If there are other instrument abnormalities, there are possibly damaged turbine components

Front 20

Who is authorized to repair a fuel flow indicating system?

Back 20

Only repaired by an FAA approved repair station certificated for the particular instruments

Front 21

Where can you find the electrical power requirements for a fuel flow indicating system?

Back 21

Aircraft maintenance manual

Front 22

Where in the fuel system is the fuel flow transmitter located?

Back 22

Between the fuel control and the fuel nozzles

Front 23

What kind of indicating system is used to measure oil temp in a small, single–engine, general aviation airplane?

Back 23

A sealed system in which a bulb, partially filled with a highly volatile liquid, is installed inside the oil strainer. The bulb is connected to a pressure gage by a copper tube. The pressure of the gas above the liquid is proportional to the temp of the oil that surrounds the bulb, and the pressure gage is calibrated in terms of temp

Front 24

What kind of electrical instrument system is used for measuring oil temp?

Back 24

Ratiometer–type system

Front 25

What is critical in the installation of the thermocouple leads for a cylinder–head temp indicator, the length of the leads or their resistance?

Back 25

Resistance is critical, it must have the resistance specified on the indicator. This is usually 2 or 8 ohms

Front 26

What should a ratiometer temp indicator read when the electrical power is off?

Back 26

Pointer should be off scale on the low side

Front 27

What kind of tach is used on small airplanes?

Back 27

Magnetic drag tach that is similar to an automobile speedometer

Front 28

What would likely cause the pointer of a magnetic drag tach to oscillate?

Back 28

Either a dry cable connecting the indicator to the engine, or a kink in the cable housing

Front 29

Is it permissible for a mechanic with a A&P to replace the tach cable for a magnetic drag tach?

Back 29

Yes, this does not constitute a repair to an instrument

Front 30

What kind of tach is used on most large multi–engine airplanes?

Back 30

Three–phase AC electric tach

Front 31

What is measured to indicate the engine RPM with a three–phase AC electric tach?

Back 31

The frequency of the AC the tach generator produces

Front 32

What kind of indicator mechanism is used to measure manifold pressure?

Back 32

Differential bellows

Front 33

What should a manifold pressure gage read when the engine is not operating?

Back 33

Existing barometric pressure

Front 34

What is used to fill the line between a fuel pressure gage and the fuel metering system?

Back 34

A light oil such as kerosine

Front 35

What could cause a fuel pressure gage to fluctuate?

Back 35

The loss of the light oil in the line between the gage and the engine

Front 36

Is a certificated mechanic with an A&P allowed to zero the pointers on a fuel pressure gage?

Back 36

No, a mechanic is not allowed to make any repairs or alterations to an aircraft instrument

Front 37

How does a ratiometer–type oil temp gage measure the temp of the oil?

Back 37

It measures the resistance of the temp bulb. The indicator is calibrated in degrees F or C rather than in ohms

Front 38

What is the range of pressure needed for a fuel pressure gage used with a float carburetor?

Back 38

Normally from 1 to 25 psi