🔍 Key Concepts

• Relationship between bearing sump pressure, surrounding compartments, and flow direction of fluids/air • Purpose of seal pressurization air in gas turbine bearings • Typical paths by which fuel or gas path products can enter the lube oil system

💭 Think About

• Think about which option directly affects the pressure differential across the bearing seals and could let outside fluids migrate into the sump. • Ask yourself: which failure would most likely change the direction of leakage across the seals—from lube oil going out, to contaminants coming in? • Consider which listed failures would mostly stop oil movement versus which would allow foreign substances to be drawn into the bearing sump.

✅ Before You Answer

• Verify the function of seal pressurization air around bearing sumps in a gas turbine. • Check which component failure would primarily cause loss of protective pressure barrier rather than simple loss of flow. • Confirm which option creates the conditions for contaminants to migrate into (not just out of) the lube oil sump.