Chapter 10: Fuel System Flashcards
types of civil jet fuels
Jet-A1 (standard)
Jet-A (USA, higher freezing point)
Jet-B (colder environment)
types of military jet fuels
JP-4
JP-5 (high flash point kerosene)
JP-8
equivalent of civil & military jet fuels
JP-4 is Jet B with corrosion inihibitor & anti icing additives
JP-8 is Jet A-1 with ~
qualities of aviation fuel
1) ‘pumpable’ and flow easily
2) relightability
3) efficient combustion
4) high calorific value
5) produce minimal harmful effects on combustor/turbine
6) minimum corrosive effects
7) reduce fire hazard to minimum
function of fuel system
1) provide engine with fuel for combustion
2) control the flow to the required quantity
3) torque motoring for control of airflow
where is the LP & HP valve located?
LP valve: aircraft fuel system
HP valve: within FCU
how is LP & HP valve controlled?
LP valve: engine fire / master switch
HP valve: engine master switch
function of LP & HP valve?
LP valve: cuts off fuel supply from aircraft
HP valve: cuts off fuel supply from FCU to nozzle
functions of FCU
compute and meter right amount of fuel to the nozzle
fuel shutoff, overspeed protection
function of fuel flow transmitter
provide signal for indication of fuel flow on a gauge
monitor excessive fuel flow to prevent high EGT
types of fuel nozzles
simplex & duplex type
conditions for good burning process
1) fuel is evenly distributed
2) well centred within combustor to prevent hot spots
function of dump valve
remove fuel in fuel manifold downstream of shutoff v/v and nozzle after engine shutdown
what state is dump valve in when fuel shutoff valve is closed?
open
benefits of EEC
1) improves efficiency by controlling components
2) enchances basic control functions (starting, de/accelerate, inflight)
3) protect engine by limiting speed/pressure
4) improve operational reliability (2 lane control)
5) easier maintenance
6) improve communications
