WASHINGTON (AP) — The Federal Aviation Administration plans to revamp oversight of airplane development after the two deadly crashes of Boeing's new 737 Max raised questions of whether the FAA has gone too far in letting companies regulate themselves, a Transportation Department official said Wednesday.

For decades, the FAA has delegated some authority for certifying new aircraft to the manufacturers themselves, reducing government costs and, defenders say, speeding the rollout of new models.

But in the wake of the air disasters in Ethiopia and Indonesia over less than five months, that practice has been seized on as evidence of an overly cozy relationship between the FAA and the industry.

The self-certifying practice, called Organization Designation Authorization, came under scrutiny Wednesday at a Senate subcommittee hearing that featured testimony by the acting FAA administrator, the Transportation Department inspector general, and the chairman of the National Transportation Safety Board.

Inspector General Calvin Scovel III said the FAA plans to significantly revamp its oversight of aircraft development by July. He gave few details in his opening statement but said the changes would include new ways to evaluate training and self-audits by aerospace companies.

Over the years, the inspector general's office has found management weaknesses in the agency's oversight, Scovel said.

In Seattle, Boeing said the process by which it designs, develops and tests planes has led to safer and safer air travel, and it sees no need for an overhaul.

The Max, featuring bigger, more efficient engines and a new automated flight-control system that has now come under suspicion in both air disasters, went into service in 2017.

Transportation Secretary Elaine Chao, who oversees the FAA, has asked Scovel to look into the way the agency certified the 737 Max as airworthy.

At the same time, the Justice Department is investigating possible criminal violations involving the airliner's certification.

Sen. Ted Cruz, R-Texas, who chaired the hearing, said the "close relationship between industry and regulators" threatens to erode the confidence of the flying public. He said commercial aviation is as safe as ever, but reports of lax oversight are frustrating. "We need to do better, and I believe that we can," he said.

The Senate Commerce Committee plans another hearing with other witnesses, including Boeing.

In his written remarks, acting FAA Administrator Daniel Elwell also hinted at coming changes at the agency but gave few details.

"We know that our oversight approach needs to evolve to ensure that the FAA remains the global leader in achieving aviation safety," he said.

Elwell also said Boeing submitted an application on Jan. 21 spelling out changes it planned to make to crucial flight-control software on the 737 Max — the system suspected of playing a role in the Oct. 29 crash of a Lion Air jet in Indonesia and the March 10 plunge of an Ethiopian Airlines Max. In all, 346 people died.

An FAA spokesman said that the Boeing submission was an "initial application" and that the agency had not yet received Boeing's completed plan for updating the software.

The Transportation Department watchdog has previously raised questions about the FAA's certification of Boeing planes and the seemingly close relationship between some agency managers and Boeing.

Elwell defended collaboration with aircraft makers and airlines, saying that sharing information gives the FAA more knowledge about emerging risks. The process, he said, has "consistently produced safe aircraft designs for decades."

The inspector general also plans to examine the widespread use of automated systems to fly airplanes, to look into whether the FAA is making sure airlines are adequately training pilots to handle situations when such features fail, and why the FAA was the last safety regulator in the world to ground the plane after the second crash.

Other regulators decided "they needed to drive risk to zero, and they did that by grounding the aircraft," Scovel said.

Elwell defended the FAA's decision, as he has before, by saying it acted as soon as "refined" tracking data indicated that the flight path of the Ethiopian plane was similar to Lion Air's. Previous data about the Ethiopian flight path, he said, was "unreliable."

Multiple investigations into the 737 Max crashes are focusing on the new automated system that can push the plane's nose down to prevent an aerodynamic stall.

Meanwhile, in Seattle, Boeing's vice president of airplane development, Mike Sinnett, briefed reporters on changes that the company is making to the flight-control system and pilot training. He repeated Boeing's confidence in the safety of the Max.

"We are working with customers and regulators around the world to restore faith in our industry and also to reaffirm our commitment to safety and to earning the trust of the flying public," Sinnett said.

Boeing also invited about 200 pilots from several airlines to its Seattle-area facility to explain to them the changes in the Max and "to get their input and to earn their trust," Sinnett said.

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Koenig reported from Dallas, Krisher from Detroit. Associated Press writer Gene Johnson in Seattle also contributed to this story.