A gas turbine engine has a nacelle providing an external skin of the engine, a casing structure radially inwards of the external skin and providing an outer surface of an air flow duct of the engine, and plural engine components located in the bay formed between the casing structure and the nacelle. The components are part of either a first set of components or a second set of components. The components of the first set are all the components from the bay which are potential ignition sources, and the components of the second set are all the remaining components from the bay. The engine further has a container located in the bay, the container being fireproof capable of withstanding the application of heat by a standard flame for 15 minutes and the container containing the components of the first set.