The most common cause of flaky beaks is a vitamin A deficiency, an issue that can easily be remedied by making sure your pet is offered a variety of fresh foods and high quality supplemental pellets.
At times, however, a beak can get whitish, flaky looking lines on it that are normal "growth" lines. Much like human fingernails, a bird's beak grows continuously throughout its life, and the new growth can cause the beak to appear streaky or striped.
If you think your bird's beak is growing abnormally, or if pieces of the beak actually flake off, the best thing to do is contact an avian vet immediately. They will be able to diagnose the problem and help your bird get back on the road to exceptional health.
To help keep your pet from developing a beak problem, offer your bird plenty of chew toys or cuttlebones to exercise and grind his beak on. This should go a long way in keeping your bird's mouth healthy, which will in turn keep your bird happy and feeling great!