As shown in the illustration, what is the purpose of pressurizing the main bearing lube oil sumps on a typical marine gas turbine? Illustration GT-0023

Correct Answer: Option B — Minimizes oil leakage from the rotor shaft.

Pressurizing bearing sumps with buffer air creates a positive pressure differential relative to the engine gas path. This prevents high-pressure hot gases from entering the bearing cavity and, conversely, prevents lubricating oil from leaking out into the turbine or compressor sections, maintaining system integrity and cleanliness.