PPLANT QUIZ 5

ENGINE INSTRUMENTATION

-Indicates oil pressure, oil temperature, engine speed, exhaust gas temperature (EGT), and fuel flow.
-Gas turbine engines have unique instruments

Turbine Inlet Temperature (TIT)

senses temperature at the inlet to the power turbine and is the most critical of all the engine variables.

Turbine Gas Temperature (TGT)

is the same as a turbine's exhaust gas temperature and both provide a relative indication of turbine inlet temperature.

Interstage Turbine Temperature (ITT)

if the probes are placed between two turbine stages, the indicator in the cockpit will display the interstage turbine temperature (ITT) and is directly proportional to the turbine inlet temperature.

N1 tachometer

Low-pressure compressor(speed).

N2 tachometer

High-pressure compressor(speed).

ENGINE PRESSURE RATIO (EPR)

-Indicates thrust produced in turbofan aircraft. -Ratio of turbine discharge pressure to compressor inlet pressure.
-Measured by EPR probes at Pt2 (inlet) and Pt7 (exhaust).
-A differential pressure transducer drives the cockpit EPR gauge.
-Changes in ambient temperature do require a correction to be applied to EPR indications to provide accurate engine power settings.

TURBINE DISCHARGE PRESSURE

-Measured at Pt7.
-Provides thrust indication when corrected for altitude, airspeed, and temperature.
-Displays the total engine internal pressure immediately aft of the last turbine stage.
-turbine discharge pressure provides an indication of thrust.

TORQUEMETER

-Used in turboprop and turboshaft engines.
-Displays engine power output in percentage units, foot-pounds, shaft horsepower, or psi.

EXHAUST GAS TEMPERATURE (EGT)

-Limits gas turbine engine operation.
-Prevents overheating of turbine blades and exhaust components.
-Measured by chromel-alumel thermocouples around the exhaust section.

FUEL-FLOW INDICATOR

-Measures fuel flow in pounds per hour (lb/hr).
-Important for monitoring fuel consumption and engine performance.

ENGINE OIL PRESSURE INDICATIONS

-Oil Pressure Indicator

THRUST REVERSER SYSTEMS

Used to assist aircraft braking after landing.

Mechanical Blockage

-Uses clamshell, inverted cone, or half-sphere.
-accomplished by placing a removable obstruction in the exhaust gas stream, usually somewhat to the rear of the nozzle.
-Found in ducted turbofan engines.
-must be able to withstand high temperatures, be mechanically strong, relatively light in weight, reliable, and "fail-safe."

Aerodynamic Blockage

-Uses translating cowl, blocker doors, and cascade vanes.
-Found in unducted turbofan engines.
-only fan air is used to slow the aircraft
-If the thrust levers are at idle position and the aircraft has weight on the wheels, moving the thrust levers aft activates the translating cowl to open closing the blocker doors.

AFTERBURNING/THRUST AUGMENTATION

-Used in military engines to increase thrust up to double the original thrust.

ENGINE STATION NUMBERING

-Assigns station numbers along a turbine engine's gas path.
-Used for locating components and taking pressure/temperature readings.

Pt2 (pressure total at station 2)

Engine inlet pressure (key station).

Pt7 (pressure is taken at station Pt7)

Turbine discharge pressure (key station).

Tt2

Engine inlet temperature (key station).

NOISE SUPPRESSION

-Jet engines produce noise from high-velocity exhaust gases mixing with ambient air.
-Turbofan engines reduce noise by mixing hot and cold gas streams.
-Noise intensity measured in decibels (dB).

Conversation

60 dB

Loud music

100+ dB

Pain threshold

130 dB

TRUE

Modern high-bypass turbofan engines produce less noise (