Abstract: A pressure relief panel for an aircraft powerplant comprises a carbon disc designed to fragment when the pressure difference across it reaches a pre-determined level. The panel is designed to totally enclose the disc and has two walls one of which is dished to form the enclosure the other of which is shaped to form a smooth continuation of the powerplant outer surface. The walls are apertured to expose the disc to both ambient pressure and the pressure in the interior of the powerplant wall, the apertures having a total area sufficient to allow passage therethrough of the flow from any of the fluid-carrying pipes within the wall should a leak or breakage occur, but the individual apertures each having an area sufficiently small to prevent escape from the enclosure of potentially dangerous pieces of the disc.