Remaining Useful Life (RUL)

Remaining Useful Life (RUL)

RUL is the estimated time left before an asset will fail under current conditions. It turns condition data into a planning number.

How RUL Is Estimated

• Data inputs — sensor trends, runtime hours, load history, and past failure records for the asset class.
• Degradation model — a curve that maps measured condition to remaining life.
• Confidence band — RUL is always a range, never a single number; plan around the lower edge for critical assets.

Planning Interventions

1. Flag assets whose lower-bound RUL falls inside the next maintenance window.
2. Schedule inspection or rebuild before the predicted failure date, with margin.
3. Re-estimate RUL after every inspection — new data should change the plan.

Tips

Never quote RUL as a single date to operations. Give a window and a confidence level, or it gets treated as a promise and you lose credibility.