What is the minimum oil temperature limit for takeoff with air temperatures below -30°C?

The minimum oil temperature limit for takeoff under conditions where the ambient air temperature is below -30°C is set to ensure the engine oil is at a suitable viscosity for optimal engine performance and protection. At temperatures below the specified threshold, oil can become too viscous, leading to inadequate lubrication of engine components during critical phases of flight, such as takeoff.

The correct answer, 15°C, reflects the need to maintain oil at a temperature that allows it to flow freely and provide proper lubrication. If the oil were allowed to remain colder than this threshold, it could result in engine wear or failure due to increased friction and reduced oil pressure. Establishing a minimum temperature of 15°C ensures that pilots can safely operate the aircraft under adverse temperature conditions while safeguarding the engine's operational integrity and reliability.

In contrast, temperatures like 0°C or 30°C might not consider the specific requirements for extreme cold conditions where oil viscosity management is critical. Furthermore, stating that the oil must be at ambient temperature does not take into account the fact that in extremely low temperatures, the ambient temperature itself is likely to be insufficient for optimal engine functioning, hence the need for a defined minimum limit that accounts for these conditions.