Engine - Propeller Control Flashcards
What is the normal take off power rating?
2475 SHP
What is the SHP in case of an engine failure during take off?
2750 SHP
Why is the duct S-shaped?
- To remove FOD that may have been ingested by inertia
- To divide the airflow into a primary flow for the engine and a secondary flow for the oil cooler
What is the accessory gearbox used for?
- driven by the high pressure compressor shaft
- operates the engine driven fuel pump, an oil pump and the DC starter/generator
- mounted at the top of the engine
Why is the high pressure spool used for engine starting?
It is smaller and lighter weight so easier to spin up
What does the propeller reduction gearbox drive?
- propeller over speed governor (POG)
- 115 V ACW generator
- propeller valve module (PVM)
- high pressure pump
- fuel cooled oil cooler (FCOC)
How is the propeller driven?
Driven by the free power turbine through a reduction gearbox
Spin by exhaust gases
How is propeller pitch controlled?
Hydro mechanically controlled by a Propeller Valve Module (PVM) installed on the reduction gearbox
How is propeller pitch changed?
Oil pressure supplied by a feathering pump which is supplied by the engines lubricating system
What does the Propeller Electronic Control (PEC) unit do?
- Control their associated PVM as well as the synchronisation of the phases of the propellers
- Controls the Pitch Change Mechanism through two channels (if one channel fails back up will take over
- Calculates correct prop speed using altitude and airspeed data and info from the Np sensors
What is the Propeller Interface Unit (PIU)?
Provides an interface between the engine controls in the flight deck and the PEC
Two PIUs installed in the electronic rack
What does the Propeller Valve Module (PVM) do?
- provides for governed constant speed operation
- power lever controlled beta range from idle to full reverse
- propeller feathering
- synchrophasing
- low prop pitch angle protection
- prop overspend protection
What are the components of the PVM?
- electro hydraulic valve
- protection valve
- feather solenoid
- rotary variable differential transducer
What does the electro hydraulic valve (EHV) do?
Meters oil to the pitch change actuator and allows a normal feathering of the prop
What does the feather solenoid do?
Acts as a back up to the electro-hydraulic valve
What does the Rotary Variable Differential Transducer do?
Adjusts and confirms the power lever angle
Where is the prop brake installed?
On a counter shaft of the right engine gearbox
When can the prop brake be engaged?
- aircraft is on the ground
- prop brake switch in the ON position
- gust lock must be engaged
- right CL must be in feather or fuel shut off position
What does the EEC do?
Controls the flow of fuel through the HMU (hydro-mechanical Unit) by means of a stepper motor
What are the EEC information inputs?
- power lever angle information
- mode selected on pwr mgt panel
- position status of the bleed air valves
- engine parameters
- air data information
What does the EEC fault light mean?
Fuel control is ON and there is an EEC failure
Fuel scheduling is fixed at the point at which the failure occurred
If fault occurred with the power lever above 52 degrees, EEC fault light will flash and movement of the affected power lever will not result in a change of power
Deselection of the affected EEC is prohibited while the FAULT light is flashing
How can you turn off a fault EEC?
Power lever should be moved below 52 degrees and the EEC light will illuminate steady
Once below 52 degrees the power lever is able to control the engine and affected EEC can be selected OFF
What FAULT light illuminates, the ENG light illuminates, master caution and a single chime
What happens to the HMU if EEC is selected OFF?
The HMU will control the fuel flow and control of the Nh will be based on the associated power lever angle
What happens to under speed control when the EEC is selected OFF?
It is lost at low power
