To bend propeller blades, heat the plastic over the flame of a candle very carefully. Be patient and hold the plastic high above the flame. You want to soften the plastic, not melt it. Remember that the thinner places are liable to melt before the thicker ones are soft. Test the plastic occasionally with a blunt instrument to make the desired bends.
Scrape smooth any sharp edges which have been rounded by the heat.
You want them to look bent, not melted. Practice this technique a few times with some plastic scraps before trying it on the model. To simulate torn jagged edges of a broken wing, sand the plastic from the inside of the piece until it is thin. A small powered hand grinder is very handy for this. Next cut through with a knife to create the jagged break.