The LO purifier heater heats which sump oil?

The LO purifier heater heats which sump oil?

• A. LO sump oil
• B. GT LO cooler sump
• C. Fuel head tank
• D. Main Reduction Gear sump oil

Answer: (D)

Heating lubricating oil in the purifier loop is about keeping the oil at a temperature where it can flow easily and be cleaned effectively. When oil is warmer, its viscosity drops, which helps the purifier separate contaminants and water and also ensures reliable lubrication for bearings and gears. The main reduction gear (MRG) relies on a heavy, high-viscosity oil to cushion and lubricate the gear teeth under load. In cold conditions this gear oil can become thick and sluggish, making it harder to pump, harder to circulate, and harder for the purifier to remove impurities. By heating the sump oil for the main reduction gear, the LO purifier heater maintains it in the proper viscosity range, which improves purification efficiency and ensures the gear receives clean, properly conditioned oil. Other sumps listed aren’t the primary targets for this heater because they belong to different subsystems or are cooled/conditioned in separate loops. The purifier heater is focused on conditioning the oil used by the main reduction gear, where maintaining consistent viscosity is most critical for propulsion reliability.

Heating lubricating oil in the purifier loop is about keeping the oil at a temperature where it can flow easily and be cleaned effectively. When oil is warmer, its viscosity drops, which helps the purifier separate contaminants and water and also ensures reliable lubrication for bearings and gears.

The main reduction gear (MRG) relies on a heavy, high-viscosity oil to cushion and lubricate the gear teeth under load. In cold conditions this gear oil can become thick and sluggish, making it harder to pump, harder to circulate, and harder for the purifier to remove impurities. By heating the sump oil for the main reduction gear, the LO purifier heater maintains it in the proper viscosity range, which improves purification efficiency and ensures the gear receives clean, properly conditioned oil.

Other sumps listed aren’t the primary targets for this heater because they belong to different subsystems or are cooled/conditioned in separate loops. The purifier heater is focused on conditioning the oil used by the main reduction gear, where maintaining consistent viscosity is most critical for propulsion reliability.