FAA Powerplant Written Practice Test

What type of defect is most likely to be found on a ball bearing assembly?

1. Cavitation

2. Brinelling

3. Galling

4. Pitting

The correct answer is: Galling

The most likely defect found on a ball bearing assembly is galling. This condition occurs when there is severe adhesive wear between the surfaces of the materials in contact, typically in conditions of high load and inadequate lubrication. During operation, especially if the bearing is subjected to extreme conditions or insufficient lubrication, metal can transfer from one surface to another, leading to material displacement and the creation of rough surfaces. Galling is particularly common in applications involving materials that exhibit a high degree of ductility and can occur during the assembly process if components are not properly lubricated. This defect results in an abrasive effect that can significantly affect the performance and lifespan of the bearing. In contrast, other defects, while possible in different contexts, are less likely to specifically affect ball bearings. For instance, cavitation refers to the formation and collapse of vapor-filled cavities in a fluid, often related to pump mechanisms rather than bearings. Brinelling is a type of permanent indentation that can occur under high static loads but is not as prevalent in properly lubricated ball bearings during regular operation. Pitting, often associated with fatigue in metal surfaces, typically occurs in gears and raceways under certain conditions, but galling stands out concerning ball bearing assemblies due to the direct contact and sliding movement of