I wouldn't advise that.
The framerate changes according to how many resources the application is using and how heavy is the current processing.
See this useful app as reference:
Try to run it and you'll see that fps change as you modify the complexity of the animation.
If you consider that the human eye can't appreciate the difference between frame rates higher that a certain level, you should just make sure that your app's frame rate is smooth enough for your animations.
If you specify too elevate a frame rate for your app you could incour in a number of performance issues.
For more info, google the Flash Player Elastic Racetrack, or:
If you really want to set fps to 60, first check this out and notice that the default is 24: