Fuel System
Fuel system in aircraft is designed to
deliver uniform flow of clean fuel from the tank to the propulsion system of
the aircraft without any interruption to power system during continuous flight
at high altitude, during all approved maneuvers. Each fuel tank is equipped with internal fuel
pumps, valves and plumbing to feed fuel to the engine to produce thrust.
Fuel system
consist multiple fuel tanks located
in the wing or fuselage base on aircraft design, intended use and as well as
age aircraft determine which fuel tank to be installed. The tanks are made of
non corrosive materials that are non reactive aviation fuel. Aluminium alloy are more commonly used in modern
aircraft fuel tank of its light weight and corrosive resistant, Synthetic rubber coated type fuel cells
are also used.
In high wing aircraft there is no need of
any pumps to feed the fuel. Gravity propels the fuel from tank to the engine. In
lighter Aircraft and low wing aircraft fuel tanks are
located inside the wing. Have filler opening at the top of the wing through
which fuel can be filled and drains in the bottom by which any moisture can be
removed, to drain fuel sample for inspection. Electrical Pump been used to pass the fuel from the tank to the Carburetor, and pressure gauge will be attached to the pump show weather the pumps
are working properly. Vent (Duct) placed to equalise the
internal pressure. Fuel selector valve
are used to avoid imbalance fuel flow and allow to choose from which tank the
fuel should flow to the Engine. Before the fuel enters the engine fuel will
passes through the Strainer where
the water and other contaminated particles are removed to avoid improper quality
fuel to flow leads to Failure of Fuel system.
Common fuel system issues
Pressurization of Fuel Tank
During maneuvering,
rolling and yawing motion of the aircraft Centrifugal force will be created due
to which pressure acts on fuel tank. During design fuel tank will undergo
analyse applying different pressure load at pitch yaw roll motion to calculate
natural frequency and resonance which may leads to the vibration of the fuel
Tank which are more effective.
Failure of Fuel pump
Pumps have
automatic bypass valves. If one valve fails other pumps will continue normal
flow to pass the failed pump. A failure pump can causes several of problems.
Fuel pump is a non serviceable part means it needs to be replaced.
Imbalance fuel flow
On flight
the usage and the movement of the fuel in the fuel tank keeps changing which
would change center of gravity of the aircraft. Many air craft have pump to
pass the fuel from one tank in the wing to another to balance level equally on
both as not to get heavier on onside. This happens because of unequal usage of
fuel by the engines. Imbalance fuel flow affects the stability of the aircraft
during flight.
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