LIGHTNING PROTECTION OF FUEL TANKS - A350 CERTIFICATION APPROACH

摘要

To demonstrate the safety of the A350 fuel tank structure and systems, taking into account both failure conditions and manufacturing variability/ageing effects, Airbus adopted a systematic approach to demonstrate (for each structural design feature) two independent layers of protection against ignition sources. This methodology allowed simple design rules which would ensure a compliant solution to be generated early in the design process. Testing to demonstrate the effectiveness of each layer was simplified (at least in concept) because with one layer of protection completely disabled, the other layer could be simply assessed by using test samples which took into account the effects of ageing and manufacturing variability. Particularly if the two layers of protection are based on different technology design features, the probability of common cause failures is drastically reduced, and the design is inherently likely to be protected against unforeseen failure conditions. This is of particular value where novel technologies or manufacturing processes are employed.