Powerplant Flashcards
Which section of a turbine drives the compressors?
Gas generator (N1/Ng)
Number of compressor stages and what it consist of:
four stage compressor assembly, 3 axial stages and 1 centrifugal stage.
In the case of the PT6, what does N1, Ng represent?
N1 is the gas generator speed, or compressor side of the turbine. Ng is the same as N1. Either marked as Ng or TURBINE.
Number of turbines and detail each one. Also state how it’s indicated in on the engine instruments:
Three turbines.
- A free (not connected to the compressor side), two stage propeller turbines (power turbines). These drive the propeller shaft and its accessories via the reduction gears. Indicated as Np
- One single-stage compressor turbine which drive the compressor side (gas generator compressor) and the accessory gear section. Indicated as N1 or Ng
Where is the accessory section and what drives it?
Aft portion of the engine and is driven by the compressor turbine shaft
What does the ‘CHIP DETECT’ caution warning mean?
It indicates that ferrous metal particles in oil have been attracted to the chip detector magnets
When the L/R ‘FUEL PRESS’ warning lights are on, what does this mean?
Outlet pressure from the Low pressure boost pump is low
Explain the purpose of the low pressure boost pump and how it’s driven
The function of the low pressure boost pump is to supply the high pressure pump with sufficient pressure to maintain cooling and lubrication. It’s engine driven and operates when the gas generator shaft N1 is turning.
Explain the purpose and operation of the fuel heater and where it is located
the fuel heater serves to maintain desired fuel temperature at the high pressure pump in-let, to prevent icing. It utilizes warm oil as a heat source and is automatic. It’s located at the high pressure pump in-let.
State what the fuel system consist of (from the firewall fuel filter and shutoff valve):
Engine driven boost pump, transducer (will trigger a warning in the case of low fuel pressure), oil-to-fuel heat exchanger, engine driver fuel pump (HP), FCU, fuel-flow transmitter, flow divider, and two fuel manifolds each with 7 simplex fuel nozzles.
Describe the Engine Auto-ignition purpose.
The engine autoignition serves to provide ignition in-case of torque loss below 400 ft/lbs, to prevent flame-out. The auto-ignition should be armed from take-off to landing.
What does the torque measurement indicate?
Indicates the torque transmitted to the engine gearbox (reduction gears).
