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What is correct regarding the fuel system?

  • A

    A fuel strainer collects unwanted particles and water.

  • B

    A pressure relief valve closes the fuel feed line in case of excessive pressure.

  • C

    A booster pump feeds the engine driven fuel pump.

  • D

    A fuel drainer is located high to take a fuel sample and drain water.

Refer to figure.
Considering each option;

"A fuel strainer collects unwanted particles and water." → It is true.
A strainer is designed to be fitted in the fuel systems just before (=upstream) the needle valve (the fuel metering device) to prevent foreign matter from entering and blocking the valve. On simple reciprocating engine aircraft, the fuel strainer is often in the form of a gascolator, that is nothing else than a simple strainer combined with a recipient to collect the unwanted solid particles.

"A pressure relief valve closes the fuel feed line in case of excessive pressure." → It is false.
A Pressure Relief Valve (PRV) is a form of safety valve used to manage and restrict build up in a pressurized hydraulic system. In simple words, It limits the system pressure to a specific set level and if this set level is reached, the pressure relief valve responds and feeds the excess flow from the system back to the tank.

A booster pump feeds the engine driven fuel pump. → It is false.
On larger air transport aircraft, each fuel tank has two LP pumps (Booster Pumps). Booster pumps are low pressure centrifugal pumps, which pressurize the fuel in the pipelines from the tank to the engine, pushing fuel towards the engine rather than engine driven pumps sucking fuel from the tanks. This ensures a constant supply at a suitable pressure to prevent vapour locking and cavitation of the HP pump supply to ensure satisfactory engine operation.

"A fuel drainer is located high to take a fuel sample and drain water." → It is false.
The fuel drain is located at the lowest point of the tank.

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