Boeing engineer Sam Salehpour arrives for the hearing in Washington on Wednesday.

Two Boeing whistleblowers testified on Wednesday before two separate US Senate committees on how the company builds airplanes and the safety of those planes.

Boeing engineer Sam Salehpour repeated what he had recently told media, that he was harassed and threatened after he raised concerns about the safety of the company's planes.

He said the company is taking shortcuts in assembling 787 Dreamliners that leave sections of an aircraft's skin vulnerable to breaking apart.

"They are putting out defective airplanes," Salehpour told members of an investigative subcommittee of the Senate Homeland Security and Governmental Affairs Committee.

"I have serious concerns about the safety of the 787 and 777 aircraft, and I'm willing to take on professional risk to talk about them."

When he raised concerns, "I was ignored", he said.

"I was told not to create delays. I was told, frankly, to shut up.

"It really scares me, believe me, but I am at peace," he said. "If something happens to me, I am at peace because I feel like coming forward; I will be saving a lot of lives."

Ed Pierson, a former Boeing manager and executive director of The Foundation for Aviation Safety, said the lack of paperwork that has been provided to National Transportation Safety Board investigators after a door plug blew out of a Boeing 737 MAX flight by Alaska Airlines in January amounted to "a criminal cover-up".

"Records do exist documenting in detail the hectic work done on the Alaska Airlines airplane, and Boeing's corporate leaders know it too, because they fought to withhold these same damning records after the two MAX crashes," he said.

Pierson said he had personally shared documents related to the missing bolts with the FBI.

Boeing recently said it has searched for records of who worked on the Alaska Airlines plane, but believes its employees did not document the work.

Neither Boeing CEO David Calhoun nor any Boeing representatives attended Wednesday's hearings. A Boeing spokesperson said the company is cooperating with the lawmakers' inquiry and offered to provide documents and briefings.

Republican and Democratic senators at both hearings expressed concerns about the testimony.

"This story is serious, even shocking," said Democratic Senator Richard Blumenthal of Connecticut, chairman of the Senate permanent subcommittee on investigations. "There are mounting, serious allegations that Boeing has a broken safety culture and a set of practices that are unacceptable."

Blumenthal said that since the hearing was announced, his committee has heard from other whistleblowers inside of Boeing. One mechanic from its nonunion South Carolina factory wrote that when he brought concerns, he was "told that hundreds of others were waiting outside the gates for our jobs".

"Boeing is at a moment of reckoning," he said. "It's a moment many years in the making. It's a moment that results not from one incident or one flight or one plane."

aiheping@chinadailyusa.com