Gas Turbine Engines Components, Inspection, Systems, And Maintenance Practice Test

In this situation the important idea is using a built-in wear indicator on the brush itself. Many starter-generator carbon brushes have a wear-indicator groove ground into the contact face. While the unit is in service, you can inspect this groove without taking the assembly apart. If the groove is still clearly visible, the brush has remaining life; as the brush wears, the groove becomes shallow and can eventually disappear, signaling that the brush needs replacement. This makes it a quick, practical way to assess wear without dismantling. Wighting the brush isn’t a reliable or practical field test because the material loss is small and requires precise, controlled weighing. Measuring the brush length could indicate wear, but it generally requires removing the brush to measure accurately. A visual color check might show overheating or contamination but does not directly indicate how much brush material remains.