CHAPTER 28 Flashcards
How is the centre tank transfer valves controlled in manual mode?
In manual mode, the centre tank transfer valves are directly controlled from the respective CTR TK P/BSW.
How is fuel transferred from the outer tanks (cells) to the engines?
There is no direct feed from the outer cells to the engines. Two inter cell transfer valves are used to transfer fuel from the outer cells to the inner cells when the fuel quantity gets to the low level.
How is the fuel used on the aircraft?
Two fuel pumps are installed in the centre tank and two other fuel pumps are installed in each wing tank inner cell. Fuel is supplied to the engines from the centre tank first. When the centre tank is empty, fuel is supplied from the wing inner cells.
How is a ECAM centre tank fuel pressure low warning generated?
The pressure switches monitor the output of the pumps through a pressure pipe. If the pressure from the centre tank pump decreases to less than 6 psi the pressure switch sends a warning signal to the ECAM system.
What valve ensures that the fuel is used in the correct chain / order?
When all the tanks contain fuel, the centre tank is emptied first. The wing tank pumps have a sequence valve to make sure that the centre tank is emptied first.
How is the centre tank fuel used first?
The sequence valve acts as a relief valve and keeps the output pressure of a wing tank pump 5 psi lower than that of the centre tank pump.
What is the purpose of the bypass suction valve is installed on the engine feed line?
A bypass suction valve is installed on the engine feed line, downstream of the main pumps. If both wing tank pumps fail with no centre tank pump running and the crossfeed valve closed, the bypass suction valve lets fuel be sucked from the wing tank by the engine fuel pump system and thus engine supply is done by “gravity”.
With the A/C is on the ground, all fuel pumps in AUTO MODE what is the effect of the slats being extended?
With the A/C is on the ground, slats extended and centre tank pumps in AUTO MODE. The centre tank pumps are not running because the slats are extended.
Using auto mode explain the centre tank operation at engine start?
During the engine start sequence and in the following 2 minutes, the centre tank pumps run regardless of the slat position. When running,
centre tank pumps have priority for engine supply over wing tank pumps. After this delay, centre tank pumps stop because slats are still extended.
When the A/C is in cruise with no faults, when would the centre tank pumps stop?
When the centre tank fuel has been used, the centre tank pumps stop automatically 5 minutes after the centre tank fuel low level has been reached. The wing tank pumps continue to supply the engines.
