Check out posts here and elsewhere, you'll find hot glue is use in many GP arfs. They can't afford the waiting time for other types of glues. UCD's landing gear uses hot glue and there has been posts here on that but I'm not sure about the firewall, unless somebody who has had his torn off can confirm if it is hot glue or something else. I've inspected a wreckage of a gp arf (avistar) and they use the same type of glue throughout the wings and fuse and yes the firewall too - hot glue! Good to know that you've broken in on the plane without problems. That's all I need to know..........