Fuel system provides refueling ,engines fuel supply, measuring the amount of fuel and control the movement of fuel on aircraft. The main objective of the fuel system is engines fuel supply. So, the reliability of the fuel system directly affects flight safety. The principle of the fuel system is quite simple and aims to supply fuel to the engine. However, implementation of this principle of ensuring efficiency and reliability requirements is a rather complicated for modern aircraft.
The fuel system consists of fuel supply systems, drainage, gas stations, control and fuel storage tanks.
Fuel is stored in special tanks, or petrol tanks. The number and placement of them varies depending on the aircraft model. Typically, fuel tanks placed in the internal central part of wing. In the case of twin jet, each engine powered with fuel contained in the relevant wing tanks .
The control of fuel and fuel mass is very important for the fuel system operation. Balancing of aircraftwith the help of fuel pumping is one of the most important functions of the fuel system.
Avionics fuel systems provide control and monitoring of the movement of fuel.
Pumping equipment ensures the movement of fuel from storage to the engine, and the circulation of fuel between tanks. The movement of fuel is depend on the processes of drainage of tanks. Drainage system is designed to fill the tanks with free air (or gas).
During the construction of modern aircraft power unit is placed in that way to provide moving of fuel with the help of Earth gravity in the situation of pump systems failure [7].
Fuel is loaded into tanks using centralized filling system. On the board of aircraft it is loaded under pressure. During refueling the process of fuel movement is controlled by specialized automated algorithms for uniform filling. In addition, the fuel system provides fuel unloading.
Fuel system of AN-148
Let's consider the example of construction of the fuel system on aircraft AN-148 (Fig. 182).
Fig. 182. Placing fuel tanks on AN-148
Fuel system of An-148 has three tanks: on in the center section and two in each of wings. Each tank placed in the wing is divided into three compartments: main, peredvytratnyy and costly. Each engine is fed with fuel of its wings. The central tank is common for two motors. Fuel is pumped it into main compartments of wing tanks from it. The structure of the fuel system of Ан-148 Fig.183.
Fig. 183 . The simplified structure of the fuel system of Аn-148
Fuel system of A-320
Fuel system of A-320 consists of a central tank, located in the center section, the two main tanks located close to the fuselage, and two wing end tanks (Fig. 184).Tanks on A-320 allow to download up to 19 thousand Kg of fuel.
Fig. 184 . The simplified structure of the fuel system on A-320
Basic and central tanks served by two pumps. The movement of fuel from wing end tanks to the main one is regulated by special valves. Fuel from each main tank used to supply the relevant engine. Fuel from the central tank with the help of pumps and valves feeds the engines. In addition, the fuel needed to power an electric generator placed in the tail part of the aircraft.
Movement of fuel is controlled by the fuel control system (Fuel Control and Monitoring System - FCMS), consisting of an evaluator (Fluel Countrol Management Computer - FCMC), and fuel database (Fuel Data Concentrator - FDC), which consists of a variety of temperature sensors, pressure sensors and fuel availability sensors .
Information about the status of fuel system from FCMS displayed by ECAM in real time mode (Fig. 185).
Fig. 185 .Displays the status of the fuel system