Final answer:
Near the fuel tank filler opening of an aircraft with a reciprocating engine, important information about the type of fuel and its octane rating or grade should be displayed to prevent misfueling and ensure proper engine function.
Step-by-step explanation:
The information that must be located near the fuel tank filler opening on an aircraft powered by a reciprocating engine is crucial for safety and operational procedures. Typically, this information includes the type of fuel, which is vital to prevent misfueling. Misfueling can lead to engine malfunction or damage.
The placard or label near the fuel tank filler opening should also indicate the octane rating or grade of the fuel that should be used, since using the incorrect octane can severely affect the performance of the engine. Additionally, in certain cases, there may be information related to the fuel/oxidant mixture if a liquid fuel system is involved, as the combustion of the fuel would require a proper oxidizer ratio for efficiency and safety.