Failure mechanisms of legacy aircraft wiring and interconnects

No Fault Found events in maintenance engineering Part 2: Root causes, technical developments and future research

“…soldering and Printed Circuit Board (PCB) assembly) and inherent design flaws which include violation against specifications. Vichare and Pecht (2006) [10], Qi et al (2008) [14] and Moffat (2008) [15] have summarized some generic causes of failures within electronic systems:…”

“…Such manifestations fracture the solder contacts and instigate intermittent faults. Electrical intermittency is also caused by contact fretting [15,20]. Fretting corrosion occur particularly in tin plated contacts, as a degradation mechanism caused by the presence of humidity which oxidizes the metal-metal interface.…”

“…When it is suspected that NFF occurs due to a lack of fault coverage by the ATE (or BITE), there comes the requirement to use additional tools which are capable of identifying the root cause of the problem. Ungar and Kirkland (2003) [79] argue that to achieve this, an understanding of the Physics-of-Failures (PoF) 15 within the operating environment is needed. Once this is known, appropriate test equipment can be selected to support the ATE which through interpretation of the physics, for example, of circuits under the test environment to be used as fault locators; a capability often beyond that of standard ATE.…”

Definitions of Test Conditions for High Voltage Aerospace Systems Using the IAGOS Atmospheric Dataset

“…This is only exacerbated under lower air pressures where PD onset can occur at lower voltages due to the changes in the discharge process associated with low pressure. If a system is operated under HV under low atmospheric pressures, greater electrical ageing is bound to accelerate any chemical and / or mechanical ageing mechanisms expected in the system [5]. The way that aerospace equipment ages in comparison to ground level equipment is likely to be different as a result of spending a majority of its flight in the environmental conditions experienced during cruise.…”

A capacitive probe for quantitative nondestructive evaluation of wiring insulation

“…The performance of the wiring that connects these key systems was not, however, a strong focus of attention until the crashes of TWA 800 and Swissair 111 [1], attributed to aging wiring. In [2], causes and modes of failure in legacy aircraft wiring have been categorized. These causes include chemical degradation such as corrosion of current carriers and hydrolytic scission of polymer chains in the insulation; electrical degradation of the insulation that may be due to concentrated electric fields at sites of electrical stress; and mechanical degradation due to vibration, over-bending and other kinds of mechanical stress.…”