First, make a roux. In a medium-size cast-iron skillet, melt the butter over medium-high heat. Stir in the flour. Cook, stirring often, about 15 to 20 minutes until the roux is deep brown in color. Watch the mixture closely and adjust the heat to keep from burning. Remove from heat and set aside.
Meanwhile, in an 8-quart pot, combine the chicken and water. Bring to a boil, reduce heat, and simmer 30 to 45 minutes, until the chicken is cooked through. Remove the chicken from the pot and set aside to cool.
Add the turkey sausage, tomatoes, onion, bell pepper, bay leaves, rosemary, thyme, and crushed red pepper to the pot. Simmer for 30 minutes. Stir in the roux into the gumbo, a spoonful at a time. Season with salt and pepper to taste. Simmer 20 to 30 minutes longer. While the gumbo is simmering, remove the skin and bones from the cooled chicken. Tear the chicken into bite-size pieces. Add the chicken, shrimp, and crabs to the pot, and cook for 5 minutes, until the shrimp is cooked through. Stir in the file powder, cooking just until the gumbo is slightly thickened.
In large soup plates, ladle the gumbo over scoops of hot rice. Sprinkle with chopped parsley and serve immediately.