Powerplant Flashcards
Max Takeoff Power SHP
5071 SHP
Describe Nl
Low pressure axial compressure
Describe Nh
High pressure centrifugal compressor
What is the engine accessory gear box driven by?
high pressure (Nh) compressor rotor
What components are on the engine accessory gear box?
Fuel Metering Unit (FMU) (Fuel Pumps)
Oil Pump
DC Starter-Generator
Permanent Magnet Alternator (PMA)
How much extra power does the FADEC deliver when the power levers are over-traveled past the rating detent?
25%
What components are mounted on the propeller reduction gear box?
Hydraulic Pump (main engine-driven pump) AC Generator Pitch Control Unit (PCU) Auxiliary Feathering Pump Propeller Overspeed Governor
Maximum reverse thrust SHP
1500 SHP
Describe the FMU.
The electro-mechanical Fuel Metering Unit is driven by the engine accessory gearbox and controls fuel flow to the engine based on signals from the FADEC.
How many fuel pumps are in the FMU?
two integral engine driven fuel pumps; a low pressure pump and a high pressure pump
What are the functions of the FADEC?
controls engine fuel flow
controls various engine bleed valves to prevent compressor surges and stalls
prevents engine overspeed
controls automatic start and shutdown
supplies voltage to the Propeller Electronic Control (PEC)
detects and indicates powerplant faults
Electrical power source for the FADEC
Permanent Magnet Alternator (PMA) driven by the accessory gearbox when Nh is above 20%; essential DC bus initially
FADEC responds to a critical fault with…
either a power stabilization to flight idle or engine shutdown.
An uptrim condition is indicated in the cockpit by:
“UPTRIM” message on ED
change in power rating from NTOP to MTOP on ED
change in torque bug position from NTOP to MTOP
A power uptrim will occur when either of the following conditions exist:
torque on the failed engine falls below 25%
power turbine speed (NPT) falls below 80%
Describe the Nh overspeed protection.
powerplant has an independent overspeed protection circuitry (dual channel) built into the FADEC which has the capability to cut off fuel flow to the engine.
Propeller system components
Propeller Electronic Control (PEC) Pitch Control Unit (PCU) Propeller Overspeed Governor Unit (POG) Auxiliary Feathering Pump Automatic Propeller Synchrophase System
Describe the PEC.
The Propeller Electronic Control is a dual channel microprocessor based controller which uses inputs from the airplane, propeller control system sensors, and the engine control system to control propeller pitch and speed.
Describe the functions of the PEC.
Autofeather
Automatic Underspeed Propeller Control
initiates power UPTRIM command to the FADEC
Describe the PCU.
The Pitch Control Unit is a hydromechanical device that uses oil PSI to control the pitch of the propellor
Describe the POG.
The Propeller Overspeed Governor unit is an independent mechanical system used to limit the propeller speed in case of a propeller overspeed malfunction;
Describe the Auxiliary Feathering Pump.
The Auxiliary Feathering Pump consists of a 28 volt DC electrical motor driving an external gear pump providing a secondary source of oil pressure for feather the propeller. The pump is automatically activated when autofeather occurs and is manually activated when alternate feather is selected.
When does the autofeather system arm?
autofeather system select ON
torque of both engines exceeds 50% and both power levers are advanced beyond a 60 degree angle.
When does the autofeather system trigger?
torque of the failed engine falls below 25% for at least three seconds
