What is the purpose of cleaning dirt off a compressor blade?

• A. Improves fuel efficiency
• B. Prevent hot starts and low engine performance
• C. Reduces noise
• D. Increases horsepower

Answer: (B)

Dirt on compressor blades harms the airflow through the compressor, reducing its aerodynamic efficiency. When the blade surfaces are dirty, airflow becomes rough and separates more easily, increasing pressure losses and lowering the effective pressure ratio. That means the engine must work harder to achieve the same thrust, and during starts this can lead to insufficient air reaching the combustor, causing hot starts and overall reduced engine performance. Cleaning the dirt restores smooth airflow and the compressor’s designed efficiency, helping the engine start reliably and perform as intended.

The other options miss the main purpose: while cleaner blades may have minor secondary benefits, the primary reason for cleaning is to prevent hot starts and degraded engine performance by maintaining proper compressor airflow.