What is the purpose of Door 65 L/R?

The purpose of Door 65 L/R on the F/A-18 E/F is primarily for servicing engine oil. This door provides access to the engine oil system, allowing maintenance personnel to check and replenish engine oil levels as needed. Proper oil maintenance is critical for engine performance and longevity, as it ensures optimal lubrication and cooling of engine components during operations.

Maintaining correct oil levels is essential for the efficient operation of the engines, as insufficient oil can lead to increased friction, overheating, and potential engine failure. Thus, Door 65 L/R plays a key role in the routine maintenance checks carried out by plane captains and maintenance crew, ensuring the aircraft remains in top operational condition.

The other options describe functions that are not associated with Door 65 L/R. For instance, servicing the APU or engine fuel filter Delta P would involve different access points and maintenance procedures specific to those systems. Thus, the designation of Door 65 L/R for engine oil servicing is what makes the answer accurate.