If you review the first two or three AF447 threads, you'll find considerable discussion of pitot tubes, and pitot heat, and the phenomenon the flight encountered.
If you go to the first page of this thread, john tullamarine provides a nice template for using the search function to look into those threads with any term you insert. If you use
pitot heat, I think you'll get to see how the discussion went.
You can try
pitot af447 site:
http://www.pprune.org/tech-log/
or
pitot heat af447 site:
http://www.pprune.org/tech-log/
and see how many posts commenting on the system there are. Then pick and choose from those.