By Robert A. “Rob” Miller
One of the two foundational concepts foundational to Conditions Based Maintenance Plus (CBM+) is Predictive Analytics Development, or PAD (the other being eRCM, or Enhanced Reliability-Centered Maintenance). PAD typically leverages information gained from sensors based on the aircraft (or other system/platform) in order to define when a particular component is performing in a marginal way which compromises system performance and/or indicates an approaching failure condition. By leveraging PAD, the supporting logistics enterprise can perform value-added action, such as executing a planned maintenance action on the given marginal component prior to an unscheduled failure or perform risk analysis prior to—for example—selecting which squadron aircraft to deploy for a selected mission.
The PAD journey on C-130J will take years, but as with any system, the smartest approach is to begin with the leveraging of any information that may already be available. The C-130J was designed with a built-in PAD network for propulsion, known as the Rolls Royce Engine Health Monitoring System, and a Lockheed Martin diagnostics system which has evolved into (as of 2012) the Data Transfer and Diagnostics System (DTADS). 2019 saw great progress in the US Air Force’s leveraging of both of these systems as a part of the overall CBM+ journey.
Prior to 2019, EHMS data was electronically downloaded by flightline maintainers or Rolls Royce Field Service Representatives (FSR) at the field level and electronically transmitted to a Rolls Royce systems engineering center for analysis. The information was then transmitted back to the field via Maintenance Advisory to the appropriate FSR. The down side to this approach, given information flow and contract structure, the MAs were effectively technical suggestions provided to the appropriate Air Force Maintenance Group (MXG). Predictably, MXG responses ran the gamut from immediate action—integrating the Rolls Royce suggestions into scheduled maintenance actions to complete disregard.
Beginning in December, the C-130 Hercules division, in conjunction with Rolls Royce, Mercer Engineering Research Center, and Air Mobility Command, began the process of integrating the EHMS-derived MAs into AIRCAT, the C-130J’s official Engineering System of Record. Protocols in development will allow MAs to flow automatically or semi-automatically—with directive engineering guidance–from Rolls Royce to the appropriate MXG via AIRCAT, thus adding authority, uniformity, and accountability required to fully leverage the expert CBM+ knowledge generated by Rolls Royce propulsion experts. Completion of this long-overdue project is expected during the 4th Quarter of Calendar Year 2020.
DTADS represents—as one of several features—the maintenance/diagnostic “brain” of the C-130J, making reams of information derived from dozens of on-board equipment-monitoring sensors instantly accessible to maintainers and engineers from the flightline/tactical level to the Program Office/strategic level of maintenance and supportability. This awesome capability comes with its own Achilles heel: Nuisance Faults due to system sensitivity. As originally specified by the Government, all faults are displayed to all levels in order to allow for easier trending analysis. The issue with this approach is that dozens to hundreds of Nuisance Faults—along with valid faults–are displayed to the flightline maintainer along with the pertinent valid information.
The filtering (or “Sentencing,” in Royal Air Force parlance) of information for different users at different levels of the logistics/maintenance community has been an ongoing project for several years, having come to the attention of the USAF in the spring of 2018. As of the Fall of 2018, a cooperative project was undertaken involving Lockheed Martin, the RAF, and the USAF with the objective of providing a simple, Government-owned software tool to flightline debrief and maintenance personnel which would filter out nuisance faults as well as allow for information trending/root cause analysis, potentially saving hundreds of man/hours per month in troubleshooting time while simultaneously increasing maintenance accuracy and quality. This software tool, known as the Fault Assertion and Sentencing Tool (FAST) underwent successful Validation/Verification at Little Rock AFB, Arkansas, on 5 December. FAST is currently moving through the wickets of Technical Data distribution and socialization through the United States Department of Defense in January ‘20, with anticipated distribution to a range of allied nations beginning in February ’20.