As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE THREADS ON THE ALTERNATE AIR VALVE BODY WERE STRIPPED OUT COMPLETELY. THE CONTROL CABLE WAS NO LONGER ATTACHED TO THE VALVE BODY, AS A RESULT THE VALVE BODY WAS FREE TO ROTATE WITHOUT RESTRICTIONS. SO THE ENGINE COULD BE GETTING UNFILTERED AIR.