Life Prediction of Aging Aircraft Wiring Systems

This proposal addresses the need for a physical model for Life Prediction of Aging Aircraft Wiring. Our primary Phase I objectives would be to (i) Identify critical aircraft wiring properties for AF Fighter aircraft. The data will be compiled and the highest frequency failure modes will be identified preferably with respect to specific aircraft locations experiencing the majority of wiring problems; (ii) Relate the most common failures identified above to wire mechanisms causing the failure. It will be necessary to understand the mechanism(s) of wire failure before initiating analysis to determine the progress of degradation. Failure modes for specific wire constructions will be identified; (iii) Select fighter aircraft for assessing wiring requirements, materials, and overall stress environments. These aircraft use large quantities of M81381 insulated wire; (iv) Demonstrate that a time, temperature, environmental (stress, fluids, etc) model can be developed. We will investigate the use of microhardness techniques to determine the ultimate tensile strength of M81381 wire insulation. Fourier transform infrared radiation (FTIR) analysis will be investigated as a secondary technique for detecting chemical changes in the M81381 wire insulation; and (v) Develop a computerized life prediction model capable of identifying present aging progress and predicting end of life for the wire in Phase II. We will seek to develop multi-parameter aging model that predicts the loss in mechanical strength that leads to cracking failure.