Hi fellow FSers,
I asked for your help in restoring missing default planes and was thinking that would retstore the missing tow plane. YOUR SOLUTION WORKED!
I reloaded the program and selected the REPAIR option. All of the default planes reloaded and all of my addon planes were untouched ( as far as I know ) and it looks like my few addon freeware scenery files are working and it also got rid of an annoying " missing file notice" that popped up everytime I loaded a plane or made a change. So you see....there is a cure for the summertime blues, as was said in a very cool "fifties song" by Eddie Cochran. Thanks again for the great help, I should have asked right you when it first happened. I hope this helps someone else.