Fault detector for a triplexed mechanical or hydromechanical system

Abstract

A fault detector for a triplexed mechanical or hydromechanical system which provides for improvement in cost, reliability and weight over previously known balance beam arrangements for achieving redundant two-channel operation to provide a fail-operating first failure mode for operation of aircraft components which require reliable operation for flight safety. The fault detector for a triplexed mechanical or hydromechanical system has a tripodal summing member which receives three mechanical position signals in three different channels with the tripodal summing member retaining a position perpendicular to the force transmitted by the tripodal summing member in response to the position signals and tipping when one of the input signals deviates significantly from the other two. A structure for detecting a malfunction senses a greater amount of movement of the tripodal summing member at its connection to the mechanical position signal which is malfunctioning to provide an indication as to which mechanical position signal is faulty. In response to detection of the faulty operation, a mechanism disconnects the channel having the faulty operation. An alignment structure is operable to restore the tripodal summing member to its normal perpendicular position to enable continued operation by means of the mechanical position signals which are still accurate.