What is galling in powerplant maintenance?

Galling is best described as a severe condition of chafing that leads to metal transfer between two surfaces in contact, typically under high pressure and low lubrication conditions. This phenomenon occurs when the surfaces of two metals slide against each other, causing one surface to tear and transfer material to the other.

In powerplant maintenance, galling can significantly affect the performance and longevity of components in engines or mechanical systems, leading to increased friction, wear, and potential failure if left unaddressed. The understanding of galling is crucial for maintaining the integrity of engine parts, especially those that experience high temperatures and pressures, like bearings and shaft assemblies.

The other options do not accurately characterize galling. While rusting involves corrosion due to moisture and oxygen, galling is strictly related to metal-on-metal contact. Cracking is a different failure mechanism that involves the formation of fractures rather than surface wear due to sliding. An acceptable wear pattern implies a regulated and monitored wear observed in components; however, galling is not that type of wear but rather an undesirable condition that often necessitates component replacement or repair.