A community hospital in Lincoln filed for bankruptcy protection Tuesday, citing steep declines in patient admissions in recent years amid a larger economic downturn in the Lincoln Lakes region. Penobscot Valley Hospital, a 25-bed critical access facility, will remain open as the Chapter 11 bankruptcy filing makes its way through federal bankruptcy court. No layoffs are planned, and the hospital’s 165 workers will continue to receive paychecks, hospital CEO Crystal Landry said.