SAE AIR6970

This SAE Aerospace Information Report (AIR) provides guidance on using environmental, electrochemical, and electrical resistance measurements to monitor environment spectra and corrosivity of service environments, focusing on parameters of interest, existing measurement platforms, deployment requirements, and data processing techniques. The sensors and monitoring systems provide discrete time-based records of (1) environmental parameters such as temperature, humidity, and contaminants; (2) measures of alloy corrosion of the sensor; and (3) protective coating performance of the sensor. These systems provide measurements of environmental parameters, sensor material corrosion rate, and sensor coating condition for use in assessing the risk of atmospheric corrosion of a structure. Time-based records of environment spectra and corrosivity can help determine the likelihood of corrosion to assess the risk of corrosion damage of the host structure for managed assets and aid in establishing maintenance intervals and processes. Diagnostics for determining damage to a structure and prognostics for predicting the remaining useful life before reaching a critical corrosion damage threshold are not within the scope of this document. Also not within the scope of this document are other nondestructive evaluation tools or structural health monitoring (SHM) technologies that can directly assess corrosion-based damage. While this document is focused on air-vehicle environments, many of these topics would translate to other industries and systems without much modification. Corrosion prevention and control is an important part of aircraft maintenance, especially for those aircraft that operate in aggressive coastal environments. Improvements to corrosion prevention and control processes necessitate an understanding of the environmental severity and cumulative exposure that aircraft experience. Recent advancements in sensing and monitoring systems allow for individual aircraft tracking of environmental parameters and corrosivity. Quantitative measurements of environment spectra and corrosivity at specific positions within individual airframes can be used to determine the influence of seasonal climatic conditions, local weather, operations, storage, and maintenance activities on aircraft corrosion for optimizing aircraft corrosion maintenance and control. These time-based records of environment spectra and corrosivity for improved maintenance would support reduced operational costs and increased aircraft availability. This document is focused on aircraft, but the technologies and approaches described in the report may apply more broadly to transportation and infrastructure.