What is required for oil tank fillers on turbine engines according to regulations?

For oil tank fillers on turbine engines, regulations stipulate that they must be marked with the word "oil." This requirement is crucial for ensuring safety and preventing the possibility of fueling errors. Clearly marking the filler with the appropriate designation helps ground personnel and pilots easily identify the correct tank to service, thereby reducing the risk of accidentally introducing fuel into an oil system, which could lead to catastrophic failures or accidents.

Marking the filler with the word "oil" serves as a straightforward visual cue that confirms the intended use of the tank. This practice aligns with industry standards aimed at maintaining safety protocols within aviation maintenance and operations.