RESTRAINT SYSTEM IN GLIDERS UNDER BIOMECHANICAL ASPECT

Abstract

In earlier times, the focus in developing gliders was above all the optimization of flight performances. Man (the occupant) was in the background when a solution for this technological challenge was looked for, and, quite deplorably, the aspect of passive safety was paid too little attention. Passive safety includes all measures inside and outside the glider which contribute to reducing the consequences of an accident. However, in recent years people became more aware of safety standards and, inspired by a series of accidents with gliders where passengers were injured fatally or severely, although the plane was not damaged notably, research was initiated to increase passive safety in gliders. In its first research, the TUV Rheinland Aviation Engineering Ltd. first investigated belt systems. ln its second research the TUV Rheinland is now examining general restraint systems in a glider. Both research orders were initiated by the LBA (Luftfahrt Bundesamt) and carried out by order of the Federal Transport Ministry, Aviation department. The tests showed that the  belt systems can only fulfil their purpose as a passive safety element if an opiimum belt geometry is maintained. This is achieved piedominantly by a correct position of the pelvic belt anchorage points. In addition the seat pan must have a clearly defined thigh contact area. The head rest should be designed to cope with the rebound effect (rigidity, energy absorbing foam). The biomechanical tests showed that man is least capable of load in vertebral direction (z-direction). This result has also been obtained from the accident analysis which showed a high proportion of vertebral injuries. In order to reduce the load on the occupants during a glider accident, the seat pan must be designed to absorb energy. Slide impact tests on an energy-absorbing seat pan showed that if the energy-absorbing element is chosen well, the load on the occupants during a glider accident can be reduced considerably. In addition it is important for the occupant of a glider to take a correct sitting position (lumbar vertebral support).