Aspects of the disclosure are directed an engine having a central longitudinal axis, comprising: a first case that at least partially defines a first flow path, a second case located radially outward of the first case, where the second case and the first case at least partially define a second flowpath, and an assembly that includes a first duct wall, a second duct wall, a finger seal disposed in a gap defined between the first duct wall and the second duct wall such that a first flow in the first flow path is isolated from a second flow in the second flowpath, a stop that projects from the first duct wall towards the second duct wall, and a diaphragm coupled to the second duct wall.