11.10 fuel systems Flashcards
what do aircraft fuel systems do
store and deliver correct fuel quantities
what must the fuel system provide
positive and reliable flow free of contamination
what is in the tank to collect contaminants and where in the tank is it
sump and drain at the lowest point in the tank
what are aircraft fitted to ensure they can land at a safe load if theres left over fuel
jettison valve
what are trim fuel tanks
fuel tanks located in trim tabs
whats the function of wing tip vent/surge tanks
ensure the fuel tanks are well ventilated
what 2 types of aircraft fuel line can there be
flexible or rigid
what are rigid fuel lines often made of
stainless steel or aluminium alloy
what fittings are used on rigid lines
military standard, navy standard
whats the material of the fuel lines used in engine compartments and why
stainless steel, susceptible to debris, abrasion and heat
where are flexible fuel lines used
areas of vibration
if a fuel line fitting is found leaking what must first be done
fitting must be re-tightened to the correct torque
what must all metal fuel lines be
electrically bonded and grounded to the aircraft
what are the 2 basic fuel types
reciprocating engine fuel (AVGAS), turbine engine fuel (jet fuel)
what is AVGAS made from and the process to get it
crude oil, fractional distillation
what are the 3 types of turbine engine fuel
jet A1, jet A, jet B
whats the density of jet A1 and jet A
0.81kg/litre
whats the freezing point of jet A
-40 degrees celcius
whats the freezing point of jet A1
-47 degrees celcius
whats the fash point range for jet A and jet A1
43-65 degrees celcius
whats the freezing point of jet B
-50 degrees celcius
why are dyes used in fuel
identify fuel type
are jet fuels dyed
no
what colour are jet fuels
colourless
what do integral fuel tanks provide
greatest space volume at lowest weight
whats the most common place for integral fuel tanks
wings
what do integral fuel tanks use to stop the fuel moving around in flight
baffles
what do baffle check valves do in integral fuel tanks
let fuel move inboard but prevent it moving outboard
whats the function of nitrogen generating systems
improve safety by reducing risk of fuel tank explosions
what is NEA
nitrogen enriched air
what two ways does the nitrogen supply system operate
low flow, high flow
when is the low flow nitrogen used
after takeoff, during climb, cruise
what can a fuel leak be repaired replacing
gasket or seal
what are the 4 classifications of fuel leaks
stain, seep, heavy seep, running leak
what size is considered a stain fuel leak
3/4 inch
what size is considered a seep fuel leak
3/4 - 1.5 inches
what size is considered a heavy seep fuel leak
1.5 - 4 inches
what size of leak is a running leak
puddle of dropping from part of the system
what does the SFAR 88 state
permanent safety of fuel tanks from the aircraft and component manufacturers
whats CDCCL
critical design control configuration limitations
before entering any fuel tank what must happen
drained and purged
what 2 people must there be when entering fuel tanks
fuel take entrant, standby person
theres air supplies for the fuel tank entrant and standby person, whats the minimum air supply per person
170 l/min
when are gravity fuel feed systems use
when the wings are higher than the engine
what aircraft cannot use gravity fuel systems
low wing aircraft
what type of fuel supply system do low wing aircraft use
pump system
what type of aircraft use injection fuel systems
high wing, single engine
what are the 5 subsystems of jet engine fuel supply systems
storage, vent, distribution, feed, indicating
whats the most common type of fuel pump on large high performance aircraft
centrifugal pump
where are centrifugal pumps located
in the fuel tank
what is used to remove foreign objects from the fuel
filters or mesh
what are the 2 major types of weight limit that aircraft shouldnt exceed
maximum takeoff, maximum landing
what does the dumping/jettison system allow the crew to do
dumb fuel overboard to prevent exceeding maximum landing weight
what does the jettison system ensure
you can dump fuel but ensures enough is kept for a go around
what are fuel vent systems designed to do
prevent build up of pressure in the fuel tanks
what are surge tanks used for
overflow fuel and prevent fuel spillage when fuelling aircraft
are surge tanks used for fuel storage
no
whats the function of flapper valves
prevent fuel traveling outboard during manoeuvres
for safety are drain valves operated manually or automatically
manually
what does the fuel transfer system allow
movement of fuel between tanks
when can the defuel valve be opened
only on ground
what do the fuel indicating systems on aircraft monitor
current conditions, unsatisfactory conditions
how many fuel flow indicators are there per engine
1
where is the fuel temp sensor usually located
main fuel tank
where are low fuel pressure sensors located
boost pump outlet line
what fuel quantity system do large and high performance aircraft employ
electronic fuel quantity systems
what is a capacitor
device that stores electricity
how many concentric plates are there per fuel tank
2
what is used to manually check fuel level on aircraft
measuring sticks
what different types of warning can there be on aircraft
visual, audible
with fuel transfer valves what light shows with abnormal fligtht conditions
light dim
with fuel transfer valves what light shows with transit
light bright
with fuel transfer valves what light shows with normal flight condition
light off
where are all the indicators shown
glass cockpit display
what are the 2 ways we can refuel
gravity, pressure
what is the most common method of refuelling an aircraft
pressure
where is the refuelling control panell
leading edge of wing
what do refuelling couplings have to protect them from dity
caps
what are the 3 modes of pressure refuelling
manual, automatic, override
describe manual refuelling
calculate fuel distribution
describe automatic refuelling
computer takes pre selection loads and calculates distribution
describe override refuelling
no electrical power to refuelling valves available
what part of the wing are refuelling valves generally attached to
front or rear spar
are solenoid operated refuelling valves fail safe
yes
what happens when power is disconnected from solenoid operated refuelling vales
valve closes
what are the 2 methods for defueling aircraft
pressure, suction
whats the minimum suction required for suction defueling
10-15 psi
what psi is used for pressure defueling
25-50 psi
does suction defueling need aircraft power
no
how big is the fuelling zone
6m (20ft)
how far out must no smoking signs be when fuelling
15m (50ft)
what does longitudinal static stability depend on
location of centre of gravity
what helps longitudinal balance when the plane if flying and using fuel
trim tabs
