

Condition-Based Maintenance Plus and Maintenance Credit Validation
Abstract
The Department of Defense (DoD) is currently maintaining the aircraft operability and functionality past the original design intention for many military aircraft. This practice imposes an additional burden on the inspection systems at the DoD logistic centers to ensure the aircraft in operation are airworthy and will be able to complete mission assignments for a specified period of time. Condition-Based Maintenance Plus (CBM+) has evolved into the U.S. Army leader priority program and becomes a critical technology for the future of the Army to reduce the logistic footprint, maximize the aircraft availability, and increase the component time on wing. To achieve these goals, the Army Research Laboratory (ARL) has initiated the CBM+ Science and Technology (S&T) Enterprise that spreads across ARL research organizations and supports the Army Research, Development, and Engineering Command CBM+ initiative in the Army fleet. The CBM+ S&T Enterprise has three Integrated Product Teams (IPTs), which focus on Hardware and Sensing, Prognostics and Diagnostics, and Data Transfer and Fusion Architecture technologies. The fourth IPT is the Technology Demonstration and Integration. It has been established that CBM, when joined with the system and/or sub-system prognostic capability (CBM+), could result in tremendous inspection savings, improved aircraft safety and availability, and decreased aircraft downtime and maintenance costs. Under these IPTs, diverse research efforts are being conducted and coordinated by the Technology Focus Working Groups (TFWGs) to combine diagnostics and prognostics capabilities. TFWGs concentrate on many technologies and processes including Structural Health Monitoring (SHM) and Maintenance Credit Validation. One of the challenges for researchers has been the development of the SHM capability that is not only effective and reliable but also relatively low cost and easy to install and maintain while performing the desired function of monitoring DoD systems and sub-systems for loss of structural integrity. SHM methods can be used to monitor the condition of critical structural components and, with other technologies, can determine the structural remaining useful life. As a result, potential maintenance credits, e.g., increased time-between-overhaul or fatigue life adjustment, can be