Boeing and General Electric pulled an engine off a new 787 Dreamliner jet for testing as U.S. officials decided to open an investigation into why the unit spewed debris over the weekend.

The National Transportation Safety Board (NTSB) will send an engine specialist and a metallurgist to a GE facility in Cincinnati to coordinate the examination, the agency said Tuesday in a statement. The NTSB said it acted after an investigator visited the scene in Charleston, S.C.

Debris blew out of the engine during a July 28 high-speed taxi test of an Air India 787 at the Charleston airport near Boeing's new factory there, igniting a brush fire along the runway and temporarily diverting and delaying flights. The safety board didn't release any new information about the damage to the engine or what might have caused it to fail.

"This is an unusual and significant failure," said Nick Cunningham, an aviation analyst at Agency Partners in London. No parts pierced the engine casing, "which is key to making it less of a safety issue."

A visual inspection Monday showed that damage was limited to the back end of the engine and doesn't indicate a fleetwide problem, said Rick Kennedy, a spokesman for GE. The cause of the engine's failure is "far from being determined" because a team will have to dismantle and examine it piece by piece, including metallurgic testing for stress points, he said.

The debris came from the low-pressure turbine area at the rear of the engine, where the blades were damaged, Kennedy said.

"This is very uncomfortable for GE, for Boeing, for anyone who flies 747-8s and for all the 787 customers who have specified GE engines," said Hans Weber, chief executive officer of San Diego-based aviation consultant Tecop International. "They're going to be working really hard to find out what happened."

The 787 incident wasn't in the same catastrophic category as the November 2010 explosion of a Rolls-Royce Holdings Trent 900 engine on an Airbus A380 superjumbo jet operated by Australia's Qantas Airways. After a safe emergency landing, Qantas grounded all six of its A380s for 23 days.

Weber said the Dreamliner incident probably wouldn't have imperiled the plane even if it had been airborne at the time, because the 787 was designed to be able to fly with just one engine, even when fully loaded, and the debris didn't puncture the casing or fuselage.

There are about 80 of the GEnx engines flying now, mostly on 747-8s, which have four engines apiece, Kennedy said. The model has about 125,000 flight hours in service so far, since both the 787 and 747-8 reached their first customers late last year, and "this is the first serious issue with the engine that we've seen," Kennedy said.

Marc Birtel, a spokesman for Chicago-based Boeing at its commercial-airplane headquarters in Seattle, said he couldn't discuss the specifics of the accident while it's being investigated.

The plane involved in the incident hadn't yet flown and wasn't painted in Air India's livery yet, Birtel said. It was the second to be built at Boeing's South Carolina plant, which opened last year.

Japan Airlines Co., the only current 787 operator using GE engines, said Monday that its Dreamliners are flying as scheduled.

The engine that failed was assembled at GE plants in Durham, N.C., and Peebles, Ohio, and installed at Boeing's North Charleston plant.

The engine failure probably stemmed from something going wrong when it was assembled, not its basic design, said Richard Aboulafia, a consultant with Teal Group in Virginia. Still, he said, "It's worrying."