Fuel Flashcards
Boost pumps powered?
Left pump DC battery bus for starting w/o ext power
Right pump powered by DC bus 2
AUTO XFLOW INHIBIT msg
The fuel automatic crossflow is inhibited
Fuel valve check test
Both pumps off
L&R amber messages and R low fuel pressure message
What is the purpose of the boost pumps
Are they required for engine start?
-Transfer from the collector to the engine
-Backup to the main ejectors
-Provide fuel pressure during engine start
No
How are the boost pumps powered
DC powered
How does APU get fuel
X-Flow APU pump gets fuel from both tanks. If not working then it uses the negative gravity relief valve
Where is the temperature of the fuel measured
Left wing and the fuel line of each engine
How does fuel stay in each tank during maneuvers
one way check valves
When will the left or right wing fuel tank quantity turn amber
- Total fuel quantity 900 lbs or less
- imbalance of more than 800lbs
What powers the fuel ejectors
Motive flow from the engine driven pump
How is fuel transferred from wing tanks to collector tanks
Scavenge Ejectors
How is fuel driven from the Collector tank to the engine driven fuel pump
Main ejector pump through motive flow which is provided by the high pressure of the engine driven fuel pump
What do transfer ejectors do?
Transfer fuel from the center tank to the wing tank
How is the fuel heated
Fuel oil heat exchanger in each engine
What happens if a fuel filter is clogged
The low pressure sends EICAS message and the filter is then bypassed
What are the 2 methods of to cross flow fuel
- Powered cross flow (automatic or manual)
- Gravity cross flow
Explain the negative gravity relief valve
Spring loaded valve that allows pressurized fuel from the right engine fuel feed manifold to feed APU
What is the function of the XFLOW/APU pump
- Supply fuel to the APU
- Perform cross flow operations
When do you get a fuel imbalance message
800lb difference between wing tanks
When does automatic crossflow initiate
When there is a rule imbalance of more than 200lbs
XFLOW/APU fills the low side to 50lbs above the other side
When does bulk fuel temp turn amber
-40c and below
When does fuel feed temp turn amber
5c and below
When does center tank quantity indicate green
10lbs or more, below this it indicates white
When is negative gravity relief valve used
-when the XFLOW/APU pump fails (deferrable)
-when a negative gravity situation exists
(not indicated on fuel synoptic page)
