NO FAULT FOUND (NFF)
The maintenance of aircraft electronic Line Replaceable Assemblies (LRUs) and Weapon Replaceable Assemblies (WRAs) pose an ever increasing challenge. Much of the challenge is related to intermittent faults which occur due to aging wiring and inter-connections. These intermittent problems manifest themselves as "bad actor" LRUs and WRAs or as repair shop No Fault Found (NFF) and Can Not Duplicate (CND) test results.
Universal Synaptics has a proven technology that augments traditional testing methods by providing an Intermittent Fault Detection and Isolation System (IFDIS) which can be used to identify and isolate intermittent faults, as well as any other wiring problems in complex LRU and WRA chassis. Now this same diagnostic capability can by used for aircraft wiring with the Voyager Intermittent Fault Detector (VIFD).
Intermittent faults are a growing problem in electronic equipment. As integrated circuits (ICs) and other electronic discrete parts become increasingly capable and reliable, an ever growing portion of the electronic equipment maintenance problems encountered are not component failures, but rather inter-connectivity problems between the electronic piece parts.
The intermittent fault can be caused by a loose or corroded wire wrap, a cracked solder joint, a corroded connector contact, a loose crimp connection, a hairline crack in a printed circuit trace, or via’s, or a number of other phenomena, all very common in electronic equipment. Many times the intermittent fault will manifest itself during an initial troubleshooting test, such as in the electronic back shop of a commercial repair facility or military flying wing, but by the time the equipment item has been transported to a commercial or military depot for repair, the intermittent circuit is no longer open. This results in NFF. LRUs and WRAs test NFF roughly 50% of the time when inducted into repair shops.