21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-6.1.4

SAFETY AND RELIABILITY PREDICTION METHODS FOR AIRCRAFT PRELIMINARY DESIGN

Fielding J. P.
Cranfield University, United Kingdom

Keywords: safety, reliability, prediction methods, aircraft preliminary design

The paper summarises several pieces of work that have been performed to integrate high reliability techniques at the very earliest design stages, where they can have most benefit. The first tool is a multi-disciplinary design programme which evaluates the effect of reliability improvement on current technology systems. The example chosen shows direct maintenance cost benefits from the use of various mass flows of avionic cooling air. The penalties on air conditioning performance and engine bleed are also evaluated and a total aircraft direct operating cost trade-off is performed. The methodology was then developed to assess reliability and maintainability effects of potentially risky new technology such as, in this case, variable-camber flaps. A further tool is one to simulate the en-route reliability and safety of transport aircraft with and without common-cause failures. It utilises MONTE-CARLO simulation and MARKOV methods and gives interesting results concerning ETOPS operations. The final tool is a novel propulsion system safety analysis methodology for commercial transport aircraft and results showed it to be significantly more accurate than current methods. All of the above tools have shown the potential for improving design methods to increase safety and reliability, with consequent social and financial benefits.

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