2450. AIRBUS A340 Weight and Balance System

Paper

Abstract

For take-off and flight planning pilots require the actual gross weight and the centre of gravity of an aircraft. A so called Weight and Balance System (WBS) has been certified in 1993 for all AIRBUS A330/A340 aircraft types. It is an on-board system which measures Gross Weight (GW) and Centre of Gravity (CG) on-ground and displays these values in real-time in the cockpit. Over a period of 5 years the WBS has proven that the achieved accuracy, reliability and robustness are far better than certified. Airlines are aware of a useful system for independently cross-check the load and trim sheet (LTS) manifest with an accuracy better than 1% of the actual aircraft weight. During development and certification tests and within a two years In-Service-monitoring phase at one customer the AIRBUS WBS has been tested in any kind of external influences to an aircraft (e.g. wind, torsion, temperatures, hard turns). Heart of system are 32 inductive sensors mounted on lugs at different locations at the landing gears. Due to the extremely high sensitivity of these sensors (working area 10_m under full load) careful installation, adjustment and a complex system calibration is required. For future aircraft programs the existing system should be improved to include some more specific functions related to the landing gears. It is very likely that ?hard landing detection? or ?landing gear monitoring? function could be included as well as new types of sensors could be found. Within a European research project it shall be demonstrated that the magnetic Barkhausen noise (known from the non-destructive testing – NDT) can be used to measure the actual weight of an on-ground aircraft in real-time. Extensive laboratory testing have to be carried out to discover the accuracy, reliability and robustness of Barkhausen Noise Sensors operating in the harsh environment of aircraft landing gears. The compensation of external influences and parameters on the micromagnetic effect is one of the challenges. Basis of the expected results is the extremely high and reproducible sensitivity of Barkhausen Noise to the stress and strain variations in the loaded components of the aircraft under weight increments. This technical paper is describing the development of the current AIRBUS WBS as well as future system developments in relation to additional functions and the use of new sensor types.