ABUJA—A small Nigerian air force passenger plane crashed just outside Abuja airport after reporting engine failure on Sunday, killing all seven people on board, the air force said. The plane, a Beechcraft King Air 350i, was on its way to the city of Minna, 110 kilometres (68 miles) northwest of the capital, said air force spokesman Ibikunle Daramole in a statement. The aircraft “crashed while returning to the Abuja Airport after reporting engine failure,” said Daramole. “First responders are at the scene. Sadly, all 7 personnel on board died in the crash.” The chief of the air force has ordered an investigation into the accident, Daramole said. In scrubland just outside the airport perimeter, dozens of military and airport officials picked through the charred remnants of the fuselage as fire engines and ambulances stood by. The smell of burning chemicals lingered in the air but no fire or smoke were …