Before Sean Bates drove into Portland on Sunday to meet a friend for lunch, he caught an advisory from the National Transportation Safety Board asking for help locating loose debris from the Boeing 737 Max 9 plane that blew a hole in its fuselage midflight over the weekend. Bates, an app developer in Vancouver, Wash., saw the search area, near where Portland meets Beaverton, was right where he was heading. An aviation enthusiast, Bates has long followed post-crash investigations, watching videos about their progress and reading blogs of experts and other hobbyists. Now, an investigation was un…