DALLAS (AP) – Boeing has stopped test flights of its new 787 passenger jet while it determines what caused smoke in the cabin and forced one of the planes to make an emergency landing in Texas.

Boeing Co. shares fell $2.11, or 3.1 percent, to $67.14 in trading Wednesday afternoon, making Boeing easily the worst performer in the Dow Jones industrial average.

On Tuesday, a 787 on a 6-hour test flight had to make an emergency landing in Texas after the crew reported smoke in the rear of the plane.

Boeing spokeswoman Loretta Gunter said Wednesday the company will ground its fleet of test planes while technicians analyze data from the stricken plane to pinpoint the cause of the smoke.

The technicians will take “as much time as they need,” Gunter said, but she held out hope test flights could resume as early as Wednesday if the problem was quickly identified.

The plane was powered by two Rolls-Royce Trent engines, but Gunter said Boeing has no reason to think the smoke came from the engines. Last week, a different model of Rolls-Royce engine on a Qantas Airbus A380 jet blew apart during a flight.

The Federal Aviation Administration is investigating Tuesday’s incident, and the National Transportation Safety Board is monitoring the situation but hasn’t sent investigators to the scene, a spokesman said.

This marks the latest setback for a plane that is already about three years behind schedule. Boeing had hoped to deliver the first 787, which it calls the Dreamliner, to Japan’s All Nippon Airways in the first quarter of next year.

Tuesday’s test plane took off from Yuma, Ariz., and flew a horseshoe-shaped route north to Montana, then east, then south to Texas. The pilot declared an emergency and landed the plane at an airport in Laredo, along the Mexico border.

According to Boeing, 42 people were aboard, including the crew and technicians who were performing a test to check the efficiency of a system used to pump nitrogen gas to the fuel tanks to reduce the risk that fuel vapors could catch fire.

Boeing said one person suffered minor injuries when the crew slid down emergency exit chutes.

Gunter said the pilot never lost primary flight displays during the incident, as some news organizations had reported Tuesday. She said information from the plane was sent for analysis in Seattle, where Boeing’s commercial aircraft division is based.

Although Boeing shares fell, one analyst said it was too soon to know the significance of the bad test flight.

“It is way too early in the process to know whether this was a one-off incident, a faulty part, or a design issue,” RBC analyst Robert Stallard wrote in a note to clients. He said the 787 is “just one small piece” in the big picture of improving conditions for aerospace companies like Boeing, and told investors to buy if shares dipped.

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