A gas turbine engine’s main lube oil system pump check valve serves to maintain system prime and perform what other function?

Correct Answer: Option B — To prevent reverse flow of oil through a secured pump.

The check valve in a gas turbine lube oil system serves a dual purpose: it maintains system prime by preventing oil drain-back and protects the system by preventing reverse flow through a secured or standby pump, ensuring that pressure is maintained only by the active, operational pump.