In a large pot or stockpot, combine the chicken parts, carrots, celery, turnips and onion, and cover with water. Over medium high heat, bring it to a boil. Lower the heat and cover, simmer gently for 1 hour, skimming the foam from the top of stock frequently during the first 30 minutes. Add the parsley, bay leaves, thyme, salt and peppercorn. Partially cover the pot with a lid. Over low heat, simmer for an additional hour, stirring occasionally. Remove the chicken and vegetables with a slotted spoon. Using a large, shallow spoon, skim the fat from the top of the stock and discard. Pour the broth through a fine strainer, press the solids to extract as much flavor and liquid as possible. You should have about 6 cups of liquid. If more has evaporated, add a bit of water. If there is too much liquid, boil down until only 6 cups remain. For completely fat free stock, refrigerate overnight, then use a large, shallow spoon to lift off and discard the solid fat. The stock may be refrigerated 2 to 3 days or frozen up to 6 months.