FUEL SYSTEM Flashcards
Parts of fuel system
1) Storage
2) Distribution
3) Fuel Indication
Wing tanks
2 x INTEGRAL (9496 (4748 per tank))
2 x SURGE
1 x COLLECTOR
How are engines supplied?
From integral tanks through collector tanks
Which tank is used by APU?
Right tank
How are engines fed?
By the means of EJECTIVE PUMP
How is APU fed?
By the means of ELECTRICAL PUMPS (AC/DC) when engines are not running
By EJECTORS when engines are running
Role of AC pumps
1) Redundancy for case of EJECTOR PUMP failure
2) Fuel pressure for engine&APU start on the ground
2 types of refueling
1) via refueling adapter (RHW) only pressure refueling
2) 2x gravity refuel ports on the top of the wing
How does the fuel flow inside the tanks?
Toward the fuselage into collector tank
Baffle and flapper check valves
Baffle and flapper check valves
1) prevent fuel from escaping of collector tank
2) prevent fuel from entering the surge tank
Purpose of tank vent system
To keep differential pressure between tank and ambient air within operational limits
To prevent fuel spillage during maneuvers and hard breaking
How is fuel drain provided?
Each tank has its own independent line into a surge tank
Where is water drain valves are located?
1) Next to AC auxiliary fuel pump (on the bottom of collector tank)
2) Close to the wing stub to wing junction
Fuel quantity measurement system consists of
1) 13 x ELECTRICAL FUEL QUALITY (PROBES)
2) 3 x MECHANICAL FUEL QUANTITY (MAGNETIC LEVEL INDICATOR)
3) Fuel temperature
4) Low level indication (independent probe (not one of the fuel indication probe)
Type of fuel measurement probes
AC capacitance-type
Which system of measurement is backup
Mechanical (floater)
When fuel temperature is indicated in amber
Below -37
How pump failure is indicated
By amber dashes
Where is temperature sensor installed?
In the left tank only
When LOW LEVEL warning is indicated?
If fuel quantity is below 300 kg
Where are magnetic sensors are mounted
3 indicators per wing mounted into fuel tank access panels
How to measure fuel quantity with a mechanical indicator
Turn it out, pull, take the value from the scale and determine the quantity with the chart from operation manual
Parts of fuel distribution system
1) Engine feed
2) APU feed
3) Refuel defuel
Means of fuel supply to the engines
1) Ejectors
2) AC pumps
Crossfeed function
Allows fuel supply to both engines from either of fuel tanks
Source of fuel supply to APU
Right tank by DC pump
Which pump is used for fuel supply to start the engine on the ground (in flight)
DC pump is used for engine start when AC power or AC fuel pump is unavailable
Mean of initial fuel supply during start
When APU is working — AC pump
After start — ejector
Low fuel pressure in engine detected
Ejector — OFF
AC PUMP (if in AUTO) — automatically starting
Mean of initial fuel supply: NO AC GPU, NO APU
DC pump
EICAS: FUEL IMBALANCE
360 kg
Disappear — 45 kg “FUEL EQUAL — XFEED OPEN”
Priority of AC PUMP selector
AC PUMP selector command overrides XFEED selector command
XFEED operation limitations
Prohibit during takeoff and landing
APU fuel supply
1) Initial supply — DC PUMP
2) AC power available — AC PUMP
3) Engine is running — EJECTOR
How to provide APU fuel supply from the left tank?
Set LOW 2
When there may appear FUEL LO LEVEL indication, if fuel quantity is adequate?
In case of scavenge pumps failure, fuel flows out from the collector tank and Fuel Low Level sensor triggers
