To my knowledge Top Flight is still in business. There's just some disturbances in the force so to speak. But I'd suggest contacting TF directly and asking about obtaining a new set of plans.
Try browsing here for info:
Top Flight
Or maybe this contact page:
Contact
I would suspect the plans are still under Copy Right in which case it would be illegal for someone to copy and distribute them. Even in electronic format.
Hint, making a copy or two of plans to aid in the construction of a kit is legal. It's the distribution part that gets you.