Preheat the oven to 350°F (175°C). Grease and flour a 9×5-inch loaf pan.
In a medium bowl, whisk together the all-purpose flour, baking soda, salt, ground cinnamon, and ground nutmeg until well combined.
In a large bowl, whisk the melted unsalted butter, granulated sugar, and light brown sugar until smooth.
Add the eggs one at a time to the butter and sugar mixture, whisking well after each addition.
Stir in the vanilla extract.
Mix in the mashed ripe bananas and crushed pineapple until evenly combined.
Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk, beginning and ending with the dry ingredients. Stir gently until just combined; do not overmix.
Fold in the chopped pecans evenly into the batter.
Pour the batter into the prepared loaf pan and smooth the top with a spatula.
Bake for 55 to 65 minutes, or until a toothpick inserted into the center comes out clean.
Remove the bread from the oven and let it cool in the pan for 10 minutes.
Transfer the bread to a wire rack and allow it to cool completely before slicing.