The MAIN XMSN OIL HOT caution indicates overheating in which system area?

• A. Main transmission oil system
• B. Electrical generator oil system
• C. Hydraulic reservoir
• D. Fuel system

Answer: (A)

The message is pointing to the main transmission oil system. In the UH-60S, the main transmission (the gearbox) has its own oil that both lubricates and cools the gear set. When the indicator says “MAIN XMSN OIL HOT,” it means the temperature of that specific oil is above the allowable limit, signaling overheating of the main transmission oil circuit. Overheating here can be caused by excessive power, heavy loads, restricted cooling, or oil system issues, and it risks gear wear or damage if not addressed.

The other options don’t fit because they refer to different oil systems: the hydraulic reservoir uses hydraulic fluid for flight control actuation, the electrical generator has its own lubrication, and the fuel system involves fuel rather than oil.