If the oil replenishment system is used, when should engines be replenished after shutdown?

The correct answer is based on the procedure for optimal oil replenishment timing after engine shutdown. When engines are shut down, it is essential to allow sufficient time for the oil to settle back into the engine components and ensure proper measurement before adding any oil if needed. The recommended period of 15 minutes to 2 hours allows for this process to occur naturally.

Replenishing oil immediately or within a very short timeframe does not provide adequate time for the oil to fully drain and settle, which can lead to inaccurate readings of the oil level and the risk of overfilling. Similarly, waiting too long beyond the 2-hour mark does not adhere to operational best practices, where a longer waiting period could lead to unnecessary delays and potential issues related to engine performance and reliability. This rationale helps ensure that the aircraft maintains its operational integrity as per the guidelines established in the aircraft's operating procedures.