I have a small airplane with no wing sheeting and my one wing is twisted quite a bit. I am wondering if I can take the twist out with the heat shrink covering. Is there a better method to untwist it?? Thanks.

Covering can take some twist out, but if it's bad, you might try weighting it down to twist it in the opposite direction, and spraying it with an amonia/water solution. Let it sit overnight and see how it looks.

If it hasn't been covered, try steaming it over a pot of boiling water, and letting it dry while weighted to twist it a little farther than you want it to be. Or dampen with Windex that has a little ammonia in it, and let it dry the same way. You might need to loosen the glue joints between the ribs and spars first. Wet and twist, let dry and reglue. If it's covered, twist and reshrink the covering. An extra set of hands and some cotton gloves are very helpful. Don't expect a one-shot success. You may have to mess with it and re-do it a few times. But usually you can get one acceptably straight
Kelvin.

I would also suggest the same to use Amonia/ Water solution and pin it over night over a flat leveled drawing board.