it is pretty useless to spray inside an engine trying to put out a fire either seen or unseen.
While I appreciate the need to protect the aircraft, I was under the impression that airport fire brigades were aware of the difference between fires in a tailpipe vs completely external fires.
I'm not saying that you can't spray where you want, but only to comment on the usefulness of this technique inside an engine. In the fire drills that I have witnessed they were designed to spray fuel in the tailpipe and elsewhere just to train the fire crews to concentrate on the elsewhere while allowing the tailpipe to eventually burn out its own residue.