Abstract: An aircraft wall assembly comprises a panel comprising a ballistic protection layer configured to deform to absorb energy during a projectile impact; and a barrier, wherein the ballistic protection layer comprises a constrained portion, wherein deformation of the ballistic protection layer is constrained at the constrained portion such that the energy absorbed by the constrained portion during the projectile impact is reduced; wherein the barrier is configured to deflect projectile material that passes through the constrained portion of the panel during the projectile impact.