Just googled this. It is a SCASM file. If you have something like SCASM 2.9, you should be able to compile it into a BGL which is used in FS as scenery.
From a BGL, you should be able to break it down into a 3DS file. From there, you can import it into Gmax and study it.
You will need to re-animate parts if they were formerly animated. BGL files are usually not animated as they are scenery, unless a flag or rotating beacon, AI cars, etc. If this is a scenery plane you want to get flying, then you will probably need to do a TON of things, like cut the ailerons out, etc, but again, you need the owners permission.
You might think about getting Gmax installed and working (free) and just start making one. You get to choose how nice it will be, etc. Its pretty good fun.
Bill