Passengers of the Delta plane that made an emergency landing at Bangor International Airport late Wednesday night were back on course Thursday morning after a seven-hour delay.

As the passengers were waiting for another plane, Delta mechanics spent the morning working on the plane, trying to find out what caused warning lights to flash in the cockpit.

The Delta L-1011 carrying 175 passengers and 15 crew members was diverted to BIA at 11:30 p.m. Wednesday after the pilot reported the plane was experiencing engine problems. The aircraft was en route to London from Cincinnati when it landed in Bangor.

Three Delta mechanics were flown in from Atlanta, Ga., early Thursday morning to work on the plane, said Doug DuPont, lead agent for Delta. By 3 p.m. the plane was being flown to Orlando, Fla.

DuPont said early Thursday afternoon that the caused of the problem hadn’t been determined. The Delta official said Thursday evening that the flight to Florida indicated that any problems had been fixed. Delta Supervisor Leonard Myers said the plane would not have been flown if problems still existed.

Passengers initially reported that they had been told there would be a two-hour delay in getting another plane. The second L-1011 didn’t leave BIA until 6:25 a.m.

Not all of the original passengers continued on to London. Myers said that a few passengers had indicated that they were too late for their business in London and returned home.

About a half-hour before the plane landed at the airport, the captain of the aircraft reported that an indicator light in the cockpit warned of a fire in one of the wheel wells. But fire officials who later inspected the plane found no traces of a fire.

While diverting to BIA, the captain reportedly unloaded 80,000 pounds of the estimated 180,000-pound load of fuel the plane was carrying for the trans-Atlantic flight. The fuel evaporated in the atmosphere before hitting the ground, an airport official said.

The plane landed with no apparent trouble as emergency vehicles and personnel stood by.

The airport was not closed because of the incident, although three other flights were delayed from departing for about 15 minutes, said Peter D’Errico, airport manager.