Corrosion of aircraft and rotorcraft costs the U.S. Department of Defense billions of dollars annually, and is the largest maintenance cost driver for the Navy and Marine Corps.1,2 Localized corrosion, such as pitting, crevice, exfoliation, and environment assisted cracking, is difficult to detect and degrades structural integrity. Currently, corrosion control is based on costly schedule based maintenance and inspection practices. To enable more efficient condition based maintenance, a wireless corrosion monitoring system has been developed that can support embedded diagnostics and prognostics. 3 ,4 The development of a robust monitoring system for aircraft structural corrosion presents multiple challenges that include sensor system design, and corrosion model development and validation in accelerated tests and service environments. Appropriate sensors must be integrated within a compact, robust package that can be easily retrofit, and that requires minimal operator attention. The need for aircraft corrosion monitoring can be met with an ultra-low power wireless sensor suite with embedded processing that is compatible with energy harvesting technology to achieve very long service life. The sensor system for monitoring environmental parameters, corrosion rates, and cumulative corrosion, and the application of these measurements to classify corrosivity are presented.
Improved health management of military aircraft is needed to control the costs of corrosion as the average age of aircraft continues to increase and operational tempos remain at high levels. The cost of corrosion as a percentage of total maintenance is estimated to be above 30% for Navy and Air Force aviation.5 High maintenance costs erode the capacity to acquire new systems, and inspection, maintenance, and repair activities degrade operational readiness. It is estimated that 90% of the total life cycle costs occur after aircraft delivery, and the costs due to corrosion continue to escalate as aircraft age.
