Adding Sensors for Condition-based Maintenance

Recently, the Joint Strike Fighter team has once again broken new ground as a result of the ever hard-working Prognostics team. This time, landing gear sensors have found their way on-board purely on the basis of improving maintenance and support costs. Previously, engine and other sensors were added on the basis of safety requirements, rather than the improvement of support costs.

The landing gear on aircraft have traditionally been a maintenance nightmare. One particular problem is the amount of hydraulic fluid present. It is measured by observation, rather than any electronic means. Since aircraft programs are extremely weight-conscious, this approach has been the solution for many years. Unfortunately, such a crude approach to this particular maintenance issue has lead to increased support costs due to damaged landing gear, due to overfilling.

The JSF program, under recommendation of the prognostics team, has now agreed to to embed sensors in the landing gear in order to report the exact level, and in doing so is projected to save hundreds of thousands of dollars over many years of maintenance.

It’s fun to argue whether the sensor is a diagnostic sensor or a prognostic sensor. While undergoing maintenance, it is certainly just a diagnostic sensor. However, during vehicle checkout, one can argue that it is a prognostic sensor because it will have data that can be trended. This, in fact, takes us to a specific battle that is going on today, which is diagnostics vs. prognostics. Yet, the result of this battle is highly predictable–a systems approach where the distinction between diagnostics and prognostics is rarely made. Instead, just as the JSF program has done, the word is “Prognostics!”