Abstract: A bellows body is curved and formed with a plurality of convolutions to allow axial and lateral flexure of both ends of the bellows when connected between the engine exhaust stack and an airframe duct. The upper slotted end of the bellows fits over the stack nipple and is conventionally, fixedly sealingly secured thereto by an O-clamp. The outside diameter of the lower end forms a gas tight slip joint in the bore of the lower cowling heater duct flange. For added reinforcement an optional collar may be permanently fitted exteriorly and/or interiorly of the stack wall adjacent the stack nipple and an optional brace may be welded interiorly between the stack and scupper.