He said that Boeing had designed a plane that could not be controlled when the automated system started to malfunction.
The Shanghai-based carrier has grounded 14 MAX planes while the USA aviation giant addresses the safety risks.
Elwell said he plans to share the FAA's "safety analysis that will form the basis for our return to service decision process" on Thursday.
Elwell told Congress last week the FAA is working closely with other civil aviation authorities "to address specific concerns related to the 737 MAX". He adds, "To me, I continue to be bullish on the aircraft".
Stephen Colbert on Trump, Pelosi, and the so-called 'temper tantrum'
She is not the president, but on his staff. "No one is above the law , including the president of the United States ". I said to her, "How very pro-woman of you", per usual, because she's not very pro-woman, she's pro some women.
Given that "there is the perception, at least, of a crisis in confidence, particularly with regard to the airplane, and maybe larger", the goal for Thursday is to "sort of fix a process that didn't, in my opinion, go in a way that we're used to internationally", Elwell said.
"It's a constant give and take until it is exactly right", Deputy FAA Administrator Dan Elwell told reporters of the discussions with Boeing. Boeing had an important hand in certifying the original Max design and the European regulator signed off on it.
The union met with Boeing after the first fatal crash, with pilots suggesting that Boeing make a safety feature standard and communicate better with pilots about what is on their planes, a recording of the meeting shared with Business Insider showed.
Boeing has said it will patch the Manoeuvering Characteristics Augmentation System (MCAS) stall prevention system, which has been blamed for the two crashes in Indonesia and Ethiopia that killed a total of 346 people and caused the best-selling planes to be taken out of service.
However US carriers appear ready to put the plane back in the air, with American Airlines and Southwest both scheduling flights using the jet for August in the apparent hope that it will be cleared to fly then.
ARM axes Huawei too; massive blow to the company
Huawei said late Wednesday that it is working with ARM about their partnership and that it hopes the situation can be resolved. The government will rule imminently whether Huawei will be allowed to participate in these new networks.
Aviation experts expect the United States agency to clear the way for the 737 MAX in time for major American airlines to resume flights in mid-to-late summer, as they have publicly announced.
Boeing and the FAA have faced sharp questions about why pilots were not given detailed information about MCAS before the crashes.
At his side during the press briefing was Ali Bahrami, the FAA's head of aviation safety, who called this "a very extensive review" of Boeing's software fix.
Dupuis said she "cannot speculate on the timelines" for approval of the 737 MAX by the FAA or Canadian officials.
New Apple MacBook Pros with up to eight cores
The company has come under criticism on social media and Apple-centric blogs and websites for the issues related to its keyboard. This year's top configuration 13-inch MacBook runs a quad-core i7 processor, which can reach boosted speeds up to 4.7GHz.