What range of oil pressure in flight is considered undesirable?

The range of oil pressure in flight categorized as undesirable is any situation where oil pressure falls below the recommended threshold for effective engine operation. Typically, operating within the range of 60 to 85 psi is considered normal; however, any pressure below this range can indicate inadequate lubrication, which could lead to increased friction and overheating, ultimately resulting in engine damage or failure.

The specific range noted below 60 psi is where oil pressure becomes concerning, potentially leading to failures or inefficiencies. Hence, the correct understanding of undesirable oil pressure would emphasize the potential risks associated with operating below the optimal levels required for engine performance and longevity.

In contrast, oil pressures above 85 psi might indicate a system that is overpressurized, though this is typically less critical than running too low. The lowest stated threshold below 40 psi is particularly alarming in aircraft operations, as it poses severe risks to engine function. Thus, the range deemed undesirable regarding flight is any pressure that compromises the safety and functionality of the aircraft's engine, emphasizing the importance of maintaining a robust oil pressure within the operational limits.