It’s not completely hollow, it has channels between the various holes that open and close selectively. The way hydraulics work requires everything to hold the hydraulic pressure, manifolds are where all of the various pressurized points meet up and get distributed to the various mechanics. If you can break that pressure seal at the manifold you can usually cripple the whole system at once. Most of a plane is run off of hydraulics, especially flight control systems.
That gets into some of the first principles of engineering a flying machine though. The hydraulics are your control for stuff like flaps and gear deployment. These things need to work consistently against pretty impressive forces, and you can only extend mechanical advantage so far before you start to run into issues with weight. Even having a backup hydraulic system would be a considerable amount of weight, and how else do you propose moving flaps and ailerons requiring hundreds or thousands of newtons of force to budge in the air?
It’s not completely hollow, it has channels between the various holes that open and close selectively. The way hydraulics work requires everything to hold the hydraulic pressure, manifolds are where all of the various pressurized points meet up and get distributed to the various mechanics. If you can break that pressure seal at the manifold you can usually cripple the whole system at once. Most of a plane is run off of hydraulics, especially flight control systems.
one would hope they have backup fly by wire systems
That gets into some of the first principles of engineering a flying machine though. The hydraulics are your control for stuff like flaps and gear deployment. These things need to work consistently against pretty impressive forces, and you can only extend mechanical advantage so far before you start to run into issues with weight. Even having a backup hydraulic system would be a considerable amount of weight, and how else do you propose moving flaps and ailerons requiring hundreds or thousands of newtons of force to budge in the air?