Design Failures in Aerospace Electrical Systems(The Identification of Sneak Circuits)

Abstract

The malfunction or failure of an aircraft electrical system because signal or power flow paths were unintentionally designed into the electrical circuit, is known to be the cause of several major failures of engineering systems. These unintentional signal or power paths are called sneak circuits. The nature of Sneak Circuits was first considered after they had been identified as the cause of some spectacular and expensive rocket failures in the United States space programme. This paper reviews the status of Sneak Circuit Analysis (SCA) and presents a general systematic approach the author has devised to identify sneak circuits during the circuits design phase. The application of the method of SCA is illustrated with a case study. The paper makes a case to take the investigation of an electrical failure or malfunction beyond the identification of a failed component to include a search for possible sneak circuits. The obvious fact that could result from the discovery of a sneak circuit is the shift in legal responsibility from the component manufacturer to the circuit designer.