A novel device for fault isolation at aircraft

Abstract

For certain avionics systems, built-in test (BIT) alone cannot accurately fault isolate to a single avionics box, or Weapons Replaceable Assembly (WRA). This is evident in the number of WRAs that are incorrectly removed and replaced at the aircraft. Such false remove and replace maintenance actions are realized in terms of increased support cost and decreased aircraft operational availability, A O . A patent-pending prototype device has been developed to break diagnostic ambiguities at the aircraft by inserting test access points between WRAs. This prototype includes a customized cylindrical Military Specification (MIL-SPEC) connector, which routes avionics bus signals to a handheld tester while the aircraft is powered on. The handheld tester analyzes data bus traffic between two functioning WRAs and provides a red, yellow, or green Light Emitting Diode (LED) output to indicate the health of the connected WRAs. The device can be reprogrammed to detect a wide range of fault indicators as they are discovered through the analysis of fielded avionics systems. This novel device provides diagnostics information at the aircraft for improved fault isolation, which may result in a significant reduction in the unnecessary cost associated with false removal and replacement of healthy WRAs.