Balanced circuits improved performance [aircraft wiring system]

Many of today´s avionics systems operate at MHz clock frequencies with input/output information exceeding one GHz. However, the signal wiring for the most part has been designed to handle electrical systems of the past that operate at frequencies below 30 MHz. This suggests that modem electronic wiring design be reviewed for flight critical systems and that wiring serving these systems treated as a balanced transmission line or power system where line losses and signal integrity are sensitive to circuit parameters. In the analysis of aircraft wiring electrical system stability is equally as critical as that of the LRU it services. This places requirements on the physical, chemical and electrical properties of wiring such as limiting capacitive reactance, inductance reactive, electromagnetic coupling and maintaining stability of electrical properties of the insulation as major factors in the control of signal distortion and line losses. Hydrolytic scission is predominately the operational stress causing insulation failure which is due to moisture intrusion, wire insulation bending and elevated temperature. Other factors contributing to systems failure during normal aircraft operations vary by aircraft zone, environment, and inadequate wire husbandry practices