Turbine Operation + Maintenance Flashcards
Tachometer is measured in ______.
Percent of RPM
The difference between two separate pressure measures in a turbine engine:
Engine pressure ratio
EPR
EPR is the ratio of _____ to the ______.
Turbine discharge pressure,
Compressor inlet pressure.
2 types of jet engines measured in torque:
Turboshaft.
Turboprop.
EGT reading after the normal redline:
Transient “Redline”
The two levers on a dual lever turboprop are _____ and _____.
Power lever.
Fuel/Condition lever.
The most catastrophic starting issue:
Hot Start.
May occurr if fuel is introduced too early in starting process
Hot start.
May occurr if starter cuts out too early:
Hung start.
Three types of turbine engine throttles systems:
1) Full Throttle
2) Flat Rated / Part Throttle
3) De-rated
Explain what is meant by a “full throttle” turbine engine.
On a standard day, the full forward position produces the rated HP.
Explain what is meant by a “flat rated” (aka part throttle) turbine engine.
Designed for a certain amount of thrust. Advance levers to achieve the desired engine measurements.
Explain what is meant by a “de-rated” turbine engine:
Capable of more HP than needed. Power lever is blocked to prevent overworking engine.
Method of turbine engine construction in which the engine is made up of several units that can be removed independent of the rest of the engine:
Modular engine construction.
The 4 steps in the “OPERATING CYCLE” of a turbine engine:
1) Starting the engine.
2) Taking off.
3) Landing.
4) Shutting the engine down.
A system of routine comparison of engine performance with a base line of the same parameters when the engine was new:
Trend Monitoring.
Maintenance program that monitors operating condition of engine and allows repairs to be made when performance deteriorates rather than on a predetermined time schedule:
On-condition maintenance
2 types of maintenance programs:
1) On-condition maintenance.
2) Trend Monitoring.
A tool used for viewing the inside of a turbine engine without having to disassemble it:
Borescope
On a single-shaft turboprop engine, the _______ lever affects the prop angle when on the ground.
Power lever.
T/F
On a free-turbine turboprop engine, the power lever increases/decreases airflow.
False.
Fuel flow.
When should a hot section inspection be performed?
On a time/cycle basis or anytime the EGT becomes excessive.
T/F
Felt tipped markers are approved for marking parts when disassembling the hot section of the engine.
True.
No lead, wax, or grease pencils allowed
4 basic rules for systematic troubleshooting:
1) Know the way the system should operate.
2) Observe how the system is operating.
3) Divide the system to find the trouble.
4) Look for obvious problem first.
A method of repairing damaged compressor and turbine blades with a file:
Blending
The high velocity stream of turbulent air behind an operating aircraft engine is called the _______.
Wake
No one should approach within ________ of an inlet duct when engine is operating.
25 feet.
The hazard area extends around _____ feet behind an idling turbojet and _____ feet behind it when the engine is developing takeoff thrust.
100.
200.
3 instruments to monitor when starting a turbine engine:
1) EGT indicator.
2) Tachometer.
3) Oil pressure gauge.
2 criteria used to determine when a turbine engine overhaul is needed:
1) Operating hours.
2) Operating cycles.
________ normally cause high EGT and unsatisfactory acceleration.
Dirty compressor blades.
T/F
When blending a compressor or turbine blade, always file perpendicular to the blade edge.
False.
Parallel to the blade edge.
2 types of liquid washing:
1) Desalination washing.
2) Performance-recovery washing.
2 ways to clean compressors:
1) Grit blasting.
2) Liquid washing.
5 parts of the hot section:
1) Fuel nozzles.
2) Combustion chambers.
3) Turbine inlet guide vanes.
4) Turbine wheels + blades.
5) Exhaust system.
Unless otherwise stated in the service manual, specified torque values are for _____, _____ threads.
Clean,
Dry.
3 components of the cold section of a turbofan engine:
1) Inlet Fan.
2) Compressor.
3) Diffuser.
The JetCal Analyzer has these three master instruments:
1) EGT.
2) Tachometer.
3) EPR.
N1 =
Rotational speed of low-pressure compressor.
The speed attained by a gas turbine engine during startup that allows it to continue with no further assistance:
Self accelerating speed
A test run to determine the way an engine’s performance compares with its performance when it was new:
Power-assurance check
4 sources of data used by the engine manufacturer for purposes of trend monitoring:
1) Fuel flow
2) EGT
3) N1
4) N2
3 basic routine inspections:
1) Pre-flight inspection
2) Cold-section inspection
3) Hot-section inspection
Rotating a turbine engine with the starter while the fuel and ignition are turned off is called:
Motoring the engine
When starting a turbine engine, engage the starter first for what reason?
To clear out any remaining fuel vapor from the combustion chamber.
Dirty compressor blades normally cause:
1) High EGT
2) Unsatisfactory acceleration
T/F
Bent compressor blades can be straightened by the mechanic.
False.
Should be sent out for major repair
T/F
Hot section inspections can usually be performed with the engine on the airframe.
True
2 critical measurments taken during hot section inspection:
1) Clearance between tips of the turbine blades and the housing.
2) Clearance between the turbine wheel and the exhaust cone.
Waviness of the leading edge of a turbine blade indicates ______.
Overheating
______ is cause for an inspection of the fan and compressors.
Overspeed
_________ is cause for inspection of the hot section.
Over-temperature
A portable testing instrument that connects to the aircraft instrument system:
JetCal analyzer
The adjustment of the fuel control to produce the required EGT or EPR at a specified RPM:
Engine trimming
On a single-shaft turboprop engine, the _______ lever affects the prop pitch while in flight.
Condition.
A maintenance program that tests the engine oil for the presence of metal particles.
Spectrometric Oil Analysis Program.
SOAP
The gas generator part of a turbofan, turboprop, or turboprop engine:
Core engine
3 instrument readings that indicate a proper light up:
1) EGT stabilized at correct temp.
2) Oil Pressure indication.
3) Stabilized fuel flow.
