Starter Generator Maintenance: Why Brush Run-In and Commutator Reconditioning Are Crucial

January 2024

The starter generator is an essential component of your aircraft, but its reliability depends on proper maintenance practices. One critical task is replacing the brushes inside. However, optimal performance goes beyond just swapping out old parts.

Brush Run-In and Commutator Reconditioning: The Basics
After installing new brushes, the commutator must be reconditioned, and the brushes need to undergo an 8–16 hour overnight run-in process. This step allows the brushes to form and fit the commutator’s surface properly. The process creates a film on the commutator, resulting in better electrical contact and improved performance.

Why the Run-In Process Matters
Although not all starter generator manufacturers mandate a run-in, I highly recommend it, especially when brushes are replaced in the field. Skipping this step can lead to other issues, including:

• Shortened brush life: Poorly seated brushes wear out faster.
• Load-carrying difficulties: Without proper contouring, the unit may struggle to meet load demands.

Extend The Life Of Your Starter Generator

1. Recondition the commutator
2. Seat the brushes properly
3. Run-in the brushes