Investigators from the National Transportation Safety Board will likely focus on the number 2 engine of the Boeing B-17 when they return Tuesday to the Oswego bean field where it made an emergency landing Monday.



The World War II era B-17 made an emergency landing in a field in Oswego, Illinois shortly after taking off from the Aurora airport.



One person was slightly injured after the plane hit the ground and burst into flames, but six others escaped without injury.



NTSB investigator Tim Sorenson said the pilot of another plane noticed that the engine closest to the fuselage on the left side appeared to be on fire, then notified the crew of the Liberty Belle, who had just taken off minutes before.



The plane skidded to a stop in front of a line of trees and the passengers managed to scramble to safety before the vintage aircraft was engulfed in flames that witnesses say reached 50 feet into the air. One of the passengers suffered a minor head injury while exiting the plane



Investigators said the crew told them about an engine problem that had grounded the plane over the weekend.



"They told us that the problem was repaired," said Sorenson.



The vintage plane, built in 1944 referred to as the "Flying Fortress,"crashed and burned at Route 71 and Minkler road in Oswego, just four miles from its takeoff. The bomber was headed toward Indianapolis.



The once-restored B-17 was owned by the Liberty Foundation, which flew it around the country giving free rides to veterans and paid rides to the public. It was one of the few remaining "Flying Fortresses" still in flyable condition.



Aviation enthusiast Gary Carter said he talked to the crew Sunday night, when they told him about fuel pump problems on the number 2 engine.



"It’s not usual for a military plane of that age to have a fuel leak,” Carter said.



Fellow enthusiast Chuck Derer agreed.



“People say every radial engine makes its own spot,” he said, referring to an oil stain on the tarmac.



Derer said he saw such a stain when he toured the Liberty Belle over the weekend at the Aurora Airport.



For now, the remains of the vintage bomber are under the protection of the Kendall County Sheriff’s office in the farm field. Tuesday the NTSB plans to truck them to a secure site so the agency can continue its investigation.



The B-17 "Flying Fortress" was the most storied aircraft the United States ever produced, and easily the most romantic airplane associated with World War II.

Over 238,000 were produced, only 12 flyable examples remained before Monday's crash (a total of 53 survive in one form or another).



The B-17 was considered nearly indestructible. German Luftwaffe pilots said it took, on average, 20 hits to bring one down. The majority were based in southern England, and flew across the English Channel on long bombing runs over Germany and occupied Europe. If there was an aircraft which defeated the Nazis, this was it.