How often should weight and balance computations be performed on an aircraft?

Weight and balance computations should be performed after significant alterations to ensure the aircraft remains within its specified limits. This is vital because significant alterations can affect the distribution of weight and the overall balance of the aircraft, which in turn influences its performance, handling characteristics, and safety.

Performing these calculations after modifications—such as the installation of new equipment, changes to passenger or cargo configurations, or adjustments to the aircraft structure—is essential for maintaining compliance with regulatory requirements and ensuring operational safety. Accurate weight and balance calculations help prevent potential issues like tail heaviness or excessive loading, which can lead to difficult handling or, in the worst-case, accidents during flight.

In contrast, while it's essential to check weight and balance for certain operations, it is not necessary to perform these computations before every flight unless there are alterations or changes in load that inherently affect the aircraft's weight and balance. Regular monthly checks or checks only after a malfunction do not adequately address the unique situations that may arise from modifications, thus making them less critical than performing computations following significant alterations.