Fuel/Anti-Stall Flashcards
Primary Function of the Turbine Engine FUEL system:
provide engine with the correct amount of fuel flow for all operating conditions.
It may also be used as servo pressure (muscle pressure) for secondary functions such as Anti-Stall Systems actuation (vbv, vsv), active clearance control operation, as well as for Oil Cooling (Engine or CSD/IDG oil).
HP engine fuel
What ATA chapter if the fuel is in the WING FUEL TANK/BOOSTER PUMP?
ATA 28
What ATA chapter if the fuel is in the Engine?
ATA 73
It cuts off fuel supply to the engine
It is controlled by ENGINE FIRE HANDLE
Also controlled by fuel/ign switch in some aircraft
SOV (Spar Valve)
____ stage pump boosts fuel flow thru fuel heater (fuel/oil heat exchanger) and can also suction fuel from wing tank.
1st stage pump/impeller pump
the _____ stage delivers high press fuel to FCU.
2nd stage / gear pump
Where can you find the fuel pump?
at the AGB attached to FCU
3 modes of Fuel heater:
Hot
Cold
Bypass
What does fuel heater uses to heat the fuel?
hot engine oil - to prevent ice formations entering the FCU
Type of filter that consist of metal screen discs and withstands HP.
Wafer Screen
Type of filter that is made up of wire screen and often formed into cone. Used in uncritical areas.
Plain mesh
Type of filter named after the particle unit.
Micron filter
Filters often have a _______ _______ switch installed to provide flight deck indication of Fuel Filter Clogging
differential pressure
______ controls the flow of fuel to the required quantity necessary for engine operating conditions (starting, decel/acceleration, cruise, take-off, landing, shut-down, emergency).
FCU
4 types of FCU
1) Hydro-Mechanical
2) Hydro- Pneumatic
3) Supervisory E.E.C.
4) Electronic (F.A.D.E.C)
Type of FCU that uses flyweight governor, cables, pushrods etc. It meters fuel to the combustion chamber iaw power demand.
Hydro-Mechanical
Type of FCU that uses 2 speed governors and is used for turboprop and turboshaft engines. Also for turbofan engines.
Uses air and fuel pressures to meter fuel
N1 governor for compressor turbines speed and N2 for power Turbine speed.
Hydro-Pneumatic
adds FADEC technology to Hydro Mechanical system (HYBRID) and not common but still found
EEC (Electronic Engine Control) operates as a limiter to prevent engine paratmeters such as tem and rpm from being exceeded.
EEC FCU System/Electronic Hydro-Mechanical
The “Dual Channel” FADEC EEC is the main and central component, it is installed on the Fan case. 1 channel manages the _____, other is in _____ ______.
engine, standby mode
The _____ meters fuel iaw commands from the EEC, it is istalled on the AGB.
HMU
EEC has a dedicated ______ that is driven by the AGB.
alternator
2 Functions associated with HMU: (HMU is fully commanded by the EEC)
Fuel Metering
Servo Control
The ____ (aka ECU) does all computing and commands HMU.
EEC
How does fuel flow indicated?
weight per hr
Type of nozzle that has 2 supply lines and 2 spray patterns at the fuel nozzle, designated Primary (inner) and Secondary (outer main) flow.
Duplex nozzle
______ _______ delivers fuel to the nozzles.
fuel manifold
________ nozzles can be either single conical spray or dual conical spray (Primary & Secondary flows), a flow divider is built into the fuel nozzle.
Simplex
______ _______ (Fuel Pressurizing and Dump Valves), aka flow dividers, serve 2 functions:
- schedule (divide) primary & secondary fuel flow to the duplex fuel nozzles
- provide positive fuel cutoff at engine shutdown by draining fuel from the fuel supply manifold(s
P&D valves
What is the purpose of draining fuel at Engine Shutdown?
Reduce the risk of a tailpipe fire due to residual fuel burning after engine is shut down (or next engine start)
Prevent carbon buildup in the fuel nozzles
2 types of drain valves:
Fuel Manifold Dump valve - located at the low points of fuel manifold
Combustor Drain Valve - runs thru a P&D valve and recovered for next engine start
gas turbine fuel:
Compressor Anti-Stall systems:
Variable Bleed Valves
Bleed bands
Variable inlet guide vanes
Variable stator vanes
Transient bleed valves
Anti-stall system located outside case of the compressor.
It opens and closes ports in the compressor case spilling INTERSTAGE COMPRESSOR AIR.
Variable bleed valves
What is the position of VBV?
Closed
Figure of an open VBV.
What will happen if primary orifice on the VBV is blocked?
bleed valve will stay open longer
It is similar to the bleed valve except that with this system, air is bled from the rear stages of the compressor through the use of a band around the compressor, rather than a single valve.
Variable bleed bands
Type of bleed valves that are frequently used on Large turbofan engines and operated by FADEC and EEC.
They are located on the last stage of the high pressure compressor and vent excess high pressure air back into the engine at the first stage turbine vanes.
Transient bleed valves
A mechanical action that changes the airflow coming into the compressor ______, or the airflow within the compressor ______.
VIGV, VSV
