A joint cover apparatus, for aircraft ducting systems for transporting high temperature pressurized gases for use in various onboard functions, for covering a joint between abutting duct sections, wherein the ducting system is provided with a leak detection system using one or more temperature-responsive sensor wires (142, 144), the joint cover apparatus comprising: a split joint cover body, operably configured to be expanded (101, 102), said split joint cover body (101, 102) being positionable circumferentially around a joint between abutting duct sections, the split joint cover body (101, 102) having an aperture therethrough, to permit the passage of gases emanating from the joint to a location external to the split joint cover body; at least one clamping mechanism (106, 108, 110), operably configured to releasably engage the split joint cover body (101, 102), to cause the split joint cover body (101, 102) to be contracted around the joint, said at least one clamping mechanism (106, 108, 110) facilitating the removal and replacement of said split joint cover body (101, 102) from the joint; a manifold block for maintaining the at least one sensor wire (142, 144) in a fixed position, relative to the aperture in the split joint cover body, for directing gases emanating from the joint into contact with the sensor wires, the manifold block having one or more gas passages (138, 140) disposed therein to conduct gases through the block and into contact with the one or more temperature-responsive sensor wires (142, 144); the manifold block comprising a block body and further including a block flange extending from said manifold block body, said manifold block body configured to enable said manifold block body to be affixed to said split joint cover body by said flange providing an overlap surface area between the manifold block and the surrounding cover body; said joint cover apparatus being characterised in that: said manifold block is positioned within the aperture of the split joint cover body (101, 102); said manifold block body is configured to be inserted into and through said aperture in said split joint cover body; and the manifold block further includes a flow control mechanism (134, 136, 146, 148, 152) for controlling the flow of gases through the one or more gas passages (138, 140) to preclude the flow of gases through the one or more gas passages when the gases emanating from the joint have a pressure that is below a preselected numerical value. a split joint cover body, operably configured to be expanded (101, 102), said split joint cover body (101, 102) being positionable circumferentially around a joint between abutting duct sections, the split joint cover body (101, 102) having an aperture therethrough, to permit the passage of gases emanating from the joint to a location external to the split joint cover body; at least one clamping mechanism (106, 108, 110), operably configured to releasably engage the split joint cover body (101, 102), to cause the split joint cover body (101, 102) to be contracted around the joint, said at least one clamping mechanism (106, 108, 110) facilitating the removal and replacement of said split joint cover body (101, 102) from the joint; a manifold block for maintaining the at least one sensor wire (142, 144) in a fixed position, relative to the aperture in the split joint cover body, for directing gases emanating from the joint into contact with the sensor wires, the manifold block having one or more gas passages (138, 140) disposed therein to conduct gases through the block and into contact with the one or more temperature-responsive sensor wires (142, 144); the manifold block comprising a block body and further including a block flange extending from said manifold block body, said manifold block body configured to enable said manifold block body to be affixed to said split joint cover body by said flange providing an overlap surface area between the manifold block and the surrounding cover body; said joint cover apparatus being characterised in that: said manifold block is positioned within the aperture of the split joint cover body (101, 102); said manifold block body is configured to be inserted into and through said aperture in said split joint cover body; and the manifold block further includes a flow control mechanism (134, 136, 146, 148, 152) for controlling the flow of gases through the one or more gas passages (138, 140) to preclude the flow of gases through the one or more gas passages when the gases emanating from the joint have a pressure that is below a preselected numerical value. said manifold block is positioned within the aperture of the split joint cover body (101, 102); said manifold block body is configured to be inserted into and through said aperture in said split joint cover body; and the manifold block further includes a flow control mechanism (134, 136, 146, 148, 152) for controlling the flow of gases through the one or more gas passages (138, 140) to preclude the flow of gases through the one or more gas passages when the gases emanating from the joint have a pressure that is below a preselected numerical value.