In the event of an onboard fire the extinguishers must be easy to reach - they
must be kept in readily accessible positions close to the main fire risk points,
e.g. the engine space and the galley.

If there's a fire in the engine space and additional air is allowed into the area the
fire will quickly escalate. To reduce the risk of this happening it's a good idea that
any portable extinguisher used to protect the engine space is capable of being
used without fully opening the primary access/engine hatch. [6.1]