28 Fuel Flashcards
what tasks need to be done by the fuel system?
- fuel storage
- fuel distribution
- fuel dumping
- indicating
what are the three most essential systems of the aircraft?
28 fuel, 32 landing gear, 27 flight controls
what regulates fuel certification requirements
subsection 951 - 1001 FAR Part 25
which fuel do reciprocating and jet engines each use?
recip -> high octane gasoline
jet -> kerosene
what is flashpoint
lowest temp at which a material will vaporize and can be ignited
how do flashpoint, density, and heating value of gasoline and jet a-1 compare
flashpoint -40, +40 (jet safer)
density: 720 vs 810 (jet slighty heavier)
heating value: 43.5 vs 42.5 (same)
why is a high flashpoint good
above the flashpoint, air bubbles form in the gas and this can lead to blockage of fuel distribution which is bad. (vapor lock)
what amount quantity is indicatied to pilots. How?
fuel mass -> more related to energy measure level (volume ) and density because density varies with temp
describe how and why water in feul is a problem and what is doen against it
how? air enters tanks when fuel leaves. air condenses (with decreasing temp).
why? less optimal engine performance
-can ice crystal and block fuel filters
sln:
water is denser so it goes to bottom, removed via water drain valves
-fuel heater before filter
describe the problem and sln of microorganisms in fuel tank
problem: they eat carbons and drink water and live in fuel tank. Problem to flow and indication. FOrm dark slime.
Sln: addatives + regularly empty tank
what is expansion space and give number
empty space (guarenteed) in fuel tank due to potential expansion of fuel from density change
2%
what is unusable fuel? what is done to reduce economic effects
fuel that is not guarenteed (under most adverve fuel feed cconditions) to be able to access.
scavenge pumps collect from from different tank areas (get in a321 down to 0.4%
what is a reason fuel can be moved around?
to change the CG and minimize trim drag
where is fuel taken from first? why?
center tank -> allow fuel weight to balance lift and reduce stress and bending moments on wing structures
what are three types of fuel tank construction
- integral
- bladder
- rigid
what are three types of fuel tank construction
- integral (part of structural members, with sealing material, baffles to prevent sloshing and checkvalves to keep fuel inboard where pumps are.
- bladder (rubber flexible, in non-fuel-tight compartment) (for double layer or light craft)
- rigid (removable, installed in a non-fuel-tight compartment for fuel tank)
describe the tank vent system on larger aircraft
vent tanks are connected to main tanks via vent pipes. They can store overflow fuel and direct it back to main tanks via vent float valves.
vent tannk is open to air via a NACA inlet which increases pressure to slightly above ambient
what is a symbiotic relationship between fuel (28) and 29 hydraulic and aircon
fuel is heat sink
what are the two principles for engine feed
gravity feed (small high wing a/c pressure feed (pumps. REQUIRED: one and a backup per engine)
types of pupms
centrifugal pump, vane pump, ejector pump
basis of centrifugal pump
inlet fuel through centrifugal impeller. (electrical connector)
ley feature of ejector pump
-to scavenge fuel from other areas
what features of tank are indicated
quantity, temp, pressure
describe capacitance quantity indicator
stick with part in fuel and part in air. Fuel part will increase capacitance
