Fuel System

All aircraft requires an uninterrupted supply of fuel at all operating conditions. An Aircraft carry significant amount of fuel on board and its weight and movement should not negatively affect the control of the aircraft in flight. A basic fuel system consists of storage tanks, pumps, filters, valves, fuel lines, metering devices, and monitoring devices. All aircraft fuel systems are designed and constructed as per aviation regulations, requirements and guidelines.

Some of the basic requirements are:

• Each fuel system must be arranged so that no fuel pump can draw fuel from more than one tank at a time
• Provision must be provided to prevent the introduction of air into the fuel system
• Failure of any one component (other than a fuel tank) should not result in the loss of power of more than one engine
• If a single fuel tank (or series of fuel tanks interconnected to function as a single fuel tank) is used on a multiengine airplane, independent tank outlets for each engine, each incorporating a shut-off valve at the tank, must be provided.
• The fuel tank must have at least two vents arranged to minimize the probability of both vents becoming obstructed simultaneously
• The filler caps must be designed to minimize the probability of incorrect installation or in-flight loss
• The fuel system must be designed and arranged to prevent the ignition of fuel vapor within the system by direct lightning strikes or swept lightning strokes
• Fuel system must deliver the fuel at the aircraft attitude that is most critical with respect to fuel feed and quantity of unusable fuel. 

Image source: Boeing-747.com