I'm looking for the title of a book or book series in th genre of juvenile fiction perhaps?

It was around the late 80s early 90s and the one book I read as a kid was the first of a series from what I remember. The story was about a group of kids whose plane crashed on an island and they had to fight against the island inhabitants - they ended up finding some secret base or something and maybe a secret room using a code word they found -"Prometheus" maybe. I remember somebody was flying a glider around dropping fire bombs. The book was pretty graphic in it's writing. For example when the plane crashed it talked about how one dead kid's brains were showing from a head wound. That's why I'm inclined to think it was a juvenile fiction genre or something like it. Not something for audiences that are too young. I had to have been at least 12 when I read it.