If an aircraft shock strut (air/oil type) bottoms upon initial landing contact, but functions correctly during taxi, what is the most probable cause?

When discussing an aircraft shock strut that bottoms out upon initial landing contact but operates correctly during taxi, the most likely cause identified as low fluid makes sense due to the way shock struts are designed to operate.

A shock strut, which is an air/oil type, relies on a specific amount of fluid to function effectively. When the aircraft lands, the strut compresses, and the fluid inside the strut absorbs the impact. If there is insufficient fluid (low fluid), there may not be enough hydraulic damping force to handle the load during hard landings, which can result in the strut bottoming out. Once the aircraft is taxiing, the load is distributed differently, and the strut may operate acceptably because the demands on it are much lighter, preventing it from bottoming out again.

Understanding this helps clarify why the other options are less likely to be the cause. Excessive weight could cause problems but would likely manifest during taxi as well. Faulty landing gear alignment might create handling issues or tire wear, but it wouldn’t specifically lead to bottoming out upon landing. Worn shock strut seals can result in fluid leakage and typically would also show a pattern of poor performance during taxi, not just upon landing.