For the gas turbine engine lube oil system...

🔍 Key Concepts

• Trace the oil flow path from the LO tank, through the lube supply filters, to the sumps and gearboxes in the illustration. • Think about what a check valve (one‑way valve) does in any piping system – what motion of the fluid does it allow, and what motion does it stop? • Compare the elevation of the LO storage/conditioning tank (LOSCA) to the engine sumps and transfer gearbox – what would gravity try to do when the pumps are secured?

💭 Think About

• When the pumps stop, what could happen to the oil in the supply lines and in the LO tank if there were no check valves? Would anything drain or flow backward? • Look carefully at where the labeled lube supply check valves are installed: are they on the pump suction, the discharge to the sumps, or the return/scavenge side? Which of the answer choices actually matches that location and function? • Ask yourself which options describe consequences of backflow or drain‑down in this system, and which option is just restating the same effect in different words.

✅ Before You Answer

• Identify exactly which valves in the drawing are the lube oil supply check valves (not the scavenge-side check valve). • Verify whether these check valves are positioned to hold oil in the supply lines to the engine or to protect the pump suction side or the tank level. • Decide if any answer choice describes a function that the supply-side check valves could not realistically perform given their location in the schematic.

For the gas turbine engine lube oil system shown in the illustration, what is the purpose of the lube oil supply check valves? Illustration GT-0024

prevent the lube oil and scavenge pump from losing its prime

keep the lube oil lines in the engine primed

prevent lube oil contained in the LO storage and conditioning tank from draining into gearboxes and sumps

All of the above

🔍 Key Concepts

💭 Think About

✅ Before You Answer