What is the recommended spare engine level to avoid having aircraft on hold for repairs?

To ensure a smooth operation and minimize the number of aircraft grounded for repairs, the recommended spare engine level is set at 8% of the total fleet. This percentage strikes a balance between having enough spare engines to effectively manage maintenance and logistical requirements without overstocking, which could result in unnecessary costs tied to inventory management and storage.

By maintaining 8% of the fleet in spare engines, an airline can mitigate downtime caused by unexpected engine repairs or maintenance, ensuring that a sufficient backup is always available. This approach aligns with industry best practices that focus on operational efficiency and cost-effectiveness while maintaining safety and reliability in aircraft operations.

Options indicating 5%, 10%, or 15% of the fleet may not provide the ideal balance needed; too low a percentage might lead to frequent aircraft delays, while too high could increase operational costs and excess inventory. Hence, 8% represents a well-considered compromise, helping to manage fleet readiness and maintenance effectively.