FAA Powerplant Written Practice Test

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

1. Corrosion

2. Galling

3. Cracking

4. Pitting

The correct answer is: Galling

A ball bearing assembly primarily relies on smooth and efficient movement between its components, which typically include balls and races. Galling, a specific type of wear characterized by the transfer of material due to adhesive friction, is especially relevant in ball bearings. This defect occurs when metal surfaces come into contact under specific conditions, potentially leading to surface damage and an increase in friction, which can impede the performance of the assembly. In the context of ball bearings, galling can occur due to insufficient lubrication, excessive load, or rapid movement that generates heat. When this happens, material from one surface can adhere to another, resulting in rough surfaces that can further degrade the assembly's operation. Recognizing galling as a common defect in ball bearing assemblies is crucial, as it directly impacts the efficiency, reliability, and lifespan of the component. Other defects, while they can occur in various mechanical assemblies, are less characteristic of ball bearing assemblies. For instance, corrosion often affects metal surfaces exposed to moisture and undesirable environments, and can be managed with proper maintenance. Cracking usually arises from fatigue or extreme stresses, while pitting is often associated with fatigue failure but is more common in applications where surface finish and loading conditions initiate localized breakdowns. Therefore, galling stands out as the