A United Airlines plane bound for Guam on Friday returned to Fukuoka Airport in southwestern Japan for an emergency landing, with no injuries reported among the about 50 passengers and crew on board, according to the transport ministry and police. Flight 166, a Boeing 737 aircraft, landed back at Fukuoka Airport at around 11:45 a.m. after declaring an emergency. The police are investigating the incident, with an irregularity in a wing flap reported. There were no reports of fire, according to the police. The runway at Fukuoka Airport was temporarily closed for safety checks following the aircr…