John, I am assuming it is the AAV md82 for FSX under the file downloads.
Some aircraft will go into the FSX files under a new folder FSX\airplane. You need to move it to the simobjects\aircraft folder.
I have just loaded it to try and it does work but there are several variables which need addressed to help you. We cannot see your computer. Give a little more information, we are here to help, but help us.
WLP
There is another way to handle this problem so that any a/c that gets installed in the "aircraft" folder will also be recognized. Create the "aircraft" folder under the main FSX directory, then edit your FSX.CFG file as follows:
...look for the lines that begin SimObjectPaths. On most systems, this will be SimObjectPaths.5=SimObjects\Misc. After this line, insert a new, blank line and type the following:
SimObjectPaths.6=Aircraft
If there's already a SimObjectPahts.6, then use the next available number...
Is worked for me with no issues. I have several a/c that installed in that folder.
John - noticed you are at Fort Polk, La just down the road from me in Ruston. Have a good friend who is an Army chaplain down there - Col Arthur. Are you Army and stationed there .. or just training through?
Wisdom begins when you finally realize someone else is in charge of the universe.