Chicago (CBS) – Federal investigators say the engine blade that broke off and triggered a deadly accident on Flight 1380 Tuesday had microscopic cracks.

43 year old Jennifer Riordan died from her injuries.

Federal investigators are analyzing how one of the 24 metal blades snapped mid-flight on the Boeing 737 engine.

When NTSB Chairman Robert Sumwalt was asked if he is concerned about the safety of all 737 planes, he responded “We are very concerned about this particular event, why did this happen? As far as trying to extrapolate that into the entire fleet of 737’s, I think that’s unwarranted at this point.”

Jennifer Riordan was sitting next to a window when the window was hit by shrapnel from the engine. She was wearing her seatbelt, but was nearly sucked out of the plane. Medical examiners say she was killed by blunt impact trauma to her head, neck, and torso.

Texas Firefighter Andrew Needum was among the passengers who pulled Riordan back inside the plane.

“I felt the calling to get up and do something, to stand up and act,” says Needum. “My heart goes out to Jennifer and her family.”

Riordan was a mother of two and Vice President at Wells Fargo. Her sister-in-law says Jennifer lived a remarkable life, saying, “She was a wonderful mother. She was just a beautiful person inside and out.”

Captain Tammie Jo Shults was in command when her plane’s engine blew, pitching the aircraft 41 degrees to the left.

“I believe captain side is where we have the damage and that’s the engine that went out,” Shults explained calmly to Airtraffic Control as she and her co-pilot Darren Ellisor steadied the 737 and began a rapid emergency descent.

The NTSB told CBS News the pilots landed the plane at about 190 miles an hour, which is about 20-25% faster than an ideal landing.

At least one member of Congress is calling for hearings on aviation safety.

NTSB Investigators expect to wrap up their initial work on site today.