Power Points Flashcards
Purpose of thrust reversals
Increase aircraft stopping power with a significant increase In weight
Benefits of thrust reversals
- Aid in braking and directional control during landing
- Back aircraft out of parking spots
- aid in emergency landing and takeoffs
4 methods if thrust reversal
- hot jet
- cold jet
- hot and cold jet
- revrse pitch propellers
2 types of operation thrust reversals
Mechanical
- clamshell
Areofynamic
- cascade vanes
Thrust reversals safe guards
- can’t be selected until throttle at idle
- not normally selected until weight on wheels is activated
- engine power can’t be increased until thrust reversals are fully deployed
- automatically return to idle if forward thrust is selected while TR are deployed
3 purposes of drive train system
Reduce speed
Increase torque
Provide drive for accessories
Components mounted on accessory gearbox
- starter motor
- fuel pump
- FCU
- oil pump
- generator
- Tachometer generator
Function of accessory gearbox
Provide mounting face and a means of drive for those components essential to start, sustain, monitor
Turbojet noise supressors
Corrugated
Lobe type nozzle
How do turbo jet noise reduction nozzles work
Changes the jet pattern reducing noise level
Modular alignment methods
- spline drive
- serrated drive
- keys and keyway
- off set bolt holes
- dowels
- witness marks
3 reasons for post maintenance activites
Prevent corrosion
Control deterioration
Eliminate physical damage
Oil pressure system components
Tank Pump Filter Relief valve Oil jets
Oil scavenge components
Strainer Scavage pump Oil cooler Tank Centrifugal breather
Low pressure air uses [5]
Customer services
Cooling HP compressor
Cooling and pressurisation of bearings
Cooling accessories
3 effects from icing
Decreased performance
FOD
Compressor surging/stalling
3 methods of ice prevention
Hot air
Electric heating
Hot oil
4 engine starting systems
Motor
Fuel sys
Ignition sys
Control sys
5 types of starters
Electric Air turbine Air impingement Gast turbine starter Cartridge type
Fire prevention methods [5]
Fire zones Fire resistant materials Explosion proof electrical equipment Drainage for leaks External cooling and vents
Fire extinguishing components
Discharge handle/buttons Fire bottles Explosive cartridges Discharge nozzles Discharge indicators
Fire discharge indicators
Electronic indicators
Skin panel indication (disks)
Mist smell
Indicators pins
What cascade vanes do
Redirect escaping exhaust gasses forward
Fuel flow measured in
Weight
Braking force of thrust reverses
Proved 20% braking force under normal conditions
How Turbo fans dampen noise
Insulating blankets/ absorbing material
Define ram effect
Result of forward movement which cuases a pile up of air in the inlet. This increases the pressure therefore increases thrust
Second operation of air inlet
Provide uniform supply of air to the compressor
Shape of subsonic inlets and why
Divergent. Increase pressure and slow down velocity
Inlet FOD protection
Inlet screens
Vortex dissipator
Partical seperators (helicotpers)
Engine monitoring things
- EPR
- Compressor and turbine speeds (RPM)
- Torquemeter
- turbine discharge pressure
- EGT
EPR indicates…
Indicates the amount of thrust the engine produces
Turbine discharge pressure gage indicates..
Amount of pressure aft of last turbine stage
Torque meter indicates
Amount of torque produced to drive prop or rotor
EGT indicates
Temp at turbine section
2 types of compressor cleaning
Fluid
Abrasive grit
Compressor bleed air HP (jeppeson)
Cabin pressurisation, anti icing, pneumatic engine starting.
Compressor stall caused by
Imbalance between inlet velocity and compressor rotational speed.
When compressor blade AoA exceeds critical AoA
Compressor mid band shrouds purpose
To make them more resistant to bending forces created by airstream
Adv of centrifugal compressor
Simplicity Low cost Low weight Low starting power requirements Good operating efficiency
Dis adv of axial flow compressors
High weight High starting power Low pressure rise per stage Expensive Difficult to manufacture
Combustion section elements:
Combustion chamber
Fuel injection sys
Ignition sys
Fuel drainage sys
Purpose of swirl vanes
To slow air down so the flame can propagate properly. Fast airflow cuases flame outd
Disadvantage of tailpipe
Reduces efficiency due to heat and duct friction losses
