(Reuters) – Schoolteacher Bob Sauer said he took a flashlight to his tree-filled backyard on Sunday evening on the small chance he might find a plane part that had torn off an Alaska Airlines jet on Friday at an altitude of about 16,000 feet (4,877 m). U.S. authorities investigating the incident on the Boeing 737 MAX 9 that depressurized the plane, leading to an emergency landing, had asked people in the Cedar Hills suburb of Portland, Oregon to look out for the missing door plug as a vital piece of evidence. “In the flashlight beam I could see that there was something gleaming white underneat…