Powerplant Flashcards
What are the typical engines on the 200? B200?
PT6A-41
PT6A-42
What is the horsepower capabilities?
850 shaft HP, 903 ESHP
What are the seven sections of the engine?
Air intake section
Compressor section
Combustion section
Turbine section
Exhaust section
Reduction gear section
Accessory drive section
Where is the air intake at?
By the air scoop under the nacelle
Where does the intake air first flow to?
The gas generator compressor
How many stages are in the compressor section?
4 - 3 axial stages, 1 centrifugal stage
What’s the function of the compressor?
Compress and supply air for combustion, cooling, pressurization, and pneumatic services
What is provided to prevent compressor stalls in the centrifugal stage?
Compressor bleed valves
When are compressor bleed valves most effective at preventing compressor stalls?
Low N1 rpm ranges
At what percent N1 do the compressor bleed valves close? What happens if they were to stick closed below this value?
90%, a compressor stall would occur
What would happen if one or both compressor bleed valves were to stick open?
ITT increase with a torque decrease while the N1 rpm remained constant
How many fuel nozzles are in the combustion chamber?
14
How many igniter plugs are in the combustion section?
2
How many reaction turbines does the PT6A use? What are they?
Free, two-stage axial propeller(power) turbine and a single-stage compressor turbine
What does the two-stage power turbine do?
Extracts energy from the combustion gases to drive the propeller and its accessories through the planetary reduction gears. This is Np.
What does the single stage compressor turbine do?
It extracts energy from the combustion gases to drive the gas generator compressor and the accessory gear section. This is N1.
What is the type of reduction gearing?
Two-stage, planetary type
What’s the purpose of the reduction gear section?
To reduce the high rpm of the free turbine to the value required for propeller operation.
It’s also used for torquemeter operation and includes drive sections for the prop governor, overspeed governor, and the prop tachgenerator.
What section forms the aft portion of the engine?
The accessory section
What is accessory section driven by?
The compressor turbine through a shaft that extends aft through the oil tank to the accessory gearbox
What’s the function of the accessory gearbox?
Drive the FCU and high pressure fuel pump, lubricating pump, N1 tachgenerator, DC starter generator, low pressure fuel boost pump, refrigerant compressor (right engine only)
What type of oil system does it have?
A dry-sump system
Where is the oil tank located?
Between the aft end of the compressor inlet and the forward end of the accessory gearbox
Where is engine oil pressure sensed?
In the pressure pump outlet line
What type of power does the engine oil pressure and oil temperature gauge require?
DC power
Where the magnetic chip detectors located?
The bottom of each reduction gearbox
Explain the operation of the oil system.
Oil pressure is drawn via a pump from the tank through various filters to engine bearings, accessory and reduction gears, prop governor, and torquemeter system.
What is oil pressure regulated by?
A relief valve
What type of pump returns the gear case oil to the tank through the oil-fuel heater? From the reduction gear case?
A scavenge pump
The fuel control system on a PT6A engine is essentially a _____ governor that increases or decreases ___ ___ to the engine to maintain selected engine operating speed.
Fuel; fuel flow
How is the low pressure boost pump driven?
By the engine
What’s the purpose of the low pressure engine driven boost pump?
Provides sufficient fuel head pressure to the high-pressure pump to maintain proper cooling and lubrication
How does the oil-to-fuel heat exchanger maintain a desired fuel temperature at the fuel pump inlet?
By using warm engine oil, uses automatic sensors
Where does fuel enter the engine fuel system through?
The oil-to-fuel heat exchanger
After flowing through the oil-to-fuel heat exchanger, where does the fuel flow?
Into the high pressure engine-driven fuel pump and then into the FCU
What will vary the flow rates through the high pressure engine-driven pump?
The gas generator (N1) RPM