28 Fuel

Question 1

what tasks need to be done by the fuel system?

Answer 1

• fuel storage
• fuel distribution
• fuel dumping
• indicating

Question 2

what are the three most essential systems of the aircraft?

Answer 2

28 fuel, 32 landing gear, 27 flight controls

Question 3

what regulates fuel certification requirements

Answer 3

subsection 951 - 1001 FAR Part 25

Question 4

which fuel do reciprocating and jet engines each use?

Answer 4

recip -> high octane gasoline

jet -> kerosene

Question 5

what is flashpoint

Answer 5

lowest temp at which a material will vaporize and can be ignited

Question 6

how do flashpoint, density, and heating value of gasoline and jet a-1 compare

Answer 6

flashpoint -40, +40 (jet safer)
density: 720 vs 810 (jet slighty heavier)
heating value: 43.5 vs 42.5 (same)

Question 7

why is a high flashpoint good

Answer 7

above the flashpoint, air bubbles form in the gas and this can lead to blockage of fuel distribution which is bad. (vapor lock)

Question 8

what amount quantity is indicatied to pilots. How?

Answer 8

fuel mass -> more related to energy 
measure level (volume ) and density 
because density varies with temp

Question 9

describe how and why water in feul is a problem and what is doen against it

Answer 9

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

Question 10

describe the problem and sln of microorganisms in fuel tank

Answer 10

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

Question 11

what is expansion space and give number

Answer 11

empty space (guarenteed) in fuel tank due to potential expansion of fuel from density change

2%

Question 12

what is unusable fuel? what is done to reduce economic effects

Answer 12

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%

Question 13

what is a reason fuel can be moved around?

Answer 13

to change the CG and minimize trim drag

Question 14

where is fuel taken from first? why?

Answer 14

center tank -> allow fuel weight to balance lift and reduce stress and bending moments on wing structures

Question 15

what are three types of fuel tank construction

Answer 15

• integral
• bladder
• rigid

Question 16

what are three types of fuel tank construction

Answer 16

• 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)

Question 17

describe the tank vent system on larger aircraft

Answer 17

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

Question 18

what is a symbiotic relationship between fuel (28) and 29 hydraulic and aircon

Answer 18

fuel is heat sink

Question 19

what are the two principles for engine feed

Answer 19

gravity feed (small high wing a/c
pressure feed (pumps. REQUIRED: one and a backup per engine)

Question 20

types of pupms

Answer 20

centrifugal pump, vane pump, ejector pump

Question 21

basis of centrifugal pump

Answer 21

inlet fuel through centrifugal impeller. (electrical connector)

Question 22

ley feature of ejector pump

Answer 22

-to scavenge fuel from other areas

Question 23

what features of tank are indicated

Answer 23

quantity, temp, pressure

Question 24

describe capacitance quantity indicator

Answer 24

stick with part in fuel and part in air. Fuel part will increase capacitance