What is meant by on-condition maintenance of a turbine engine?

• A. Routine maintenance at fixed intervals regardless of data.
• B. Maintenance based on observed operating parameters and manufacturer specifications.
• C. Replacing major components on a fixed schedule.
• D. Maintenance only after a maintenance event with no data.

Answer: (C)

On-condition maintenance means using actual health data from the engine to decide when maintenance is needed, rather than sticking to a fixed schedule. It relies on observed operating parameters and manufacturer specifications to trigger service actions. This approach looks at how the engine is performing and what the data shows—from oil analysis, vibration and temperature trends, and borescope inspections to performance measurements—and only schedules maintenance when those health indicators exceed defined thresholds.

The concept is about diagnosing the engine’s condition from real-time or trending data and then acting accordingly, which helps avoid unnecessary maintenance while preventing unexpected failures. Replacing major components on a fixed schedule is time- or mileage-based, not condition-based, so it doesn’t align with on-condition maintenance.