In Engpsh, the fuel tank on the left side is typically referred to as the "left fuel tank" or "fuel tank on the left side". This phrase is simply a straightforward description of the location of the fuel tank.

Here are a few example sentences and their translations:

The pilot checked the fuel levels in the left fuel tank before takeoff. (飞行员在起飞前检查了左边的油箱水平。)
The mechanic drained the left fuel tank and refilled it with fresh fuel. (机械师排空了左边的油箱并用新的燃料加满了它。)
The left fuel tank was damaged in the accident and needed to be replaced. (在事故中左边的油箱受损并需要更换。)

The phrase "left fuel tank" simply describes the location of the fuel tank, with "left" referring to the direction of the tank. It is not a commonly used term, and there may not be any specific origin or history behind it.