The Application of Redundancy to Achieve A Fail-Operative Flight Control System

A design concept for implementing triple-redundant flight control equipment is presented and discussed. Redundancy is required to achieve fail-operative performance in critical flight regimes. A method for passive signal selection in analog control systems is described which utilizes the amplitude-selective properties of conventional digital logic gates. It is shown that an overall improvement in reliability and tolerance spreads can be achieved using this technique in a parallel-series array of functional elements. An ¿off-line¿ monitoring method is described to permit failure warning indication for cockpit display, and which facilitates fault isolation when used in conjunction with self-test circuits and a maintenance panel display.