CHICAGO (CBS/AP) — The U.S. Department of Transportation is setting up a committee of experts to conduct an independent review of the Federal Aviation Authority’s certification of the Boeing 737 Max, amid increased scrutiny in the wake of two fatal crashes in less than five months.

Boeing and the FAA are already the subject of investigations by the Justice Department, the Transportation Department’s inspector general, and congressional committees.

Federal authorities have instructed Boeing and FAA employees to retain documents relating to the plane’s approval process, which by design relies on manufacturers like Boeing to self-police that it’s met FAA requirements.

Retired Air Force General Darren McDew and Captain Lee Moak, who is the former president of the Air Line Pilots Association, will serve as interim co-chairs of the Transportation Department’s special committee while other members are appointed.

In a statement, Chicago-based Boeing said it looks forward “to working with the Special Committee to advance our shared goal of an aviation industry that is safe and trusted by the flying public. Safety is our top priority when we design, build, deliver and maintain Boeing aircraft.”

Its statement went on to say that it has worked to make flying safe by engaging “with the DOT, FAA, our airline customers as well as other aviation community partners for decades.”

The committee’s findings and recommendations will be presented to Transportation Secretary Elaine Chao, and Acting FAA Administrator Daniel Elwell.

The announcement comes ahead of Chao’s scheduled appearance before the Senate Transportation, Housing and Urban Development, and Related Agencies subcommittee budget hearing on Wednesday morning.

Chao’s team is preparing for a grilling from concerned lawmakers, and Chao said in a statement, “This review by leading outside experts will help determine if improvements can be made to the FAA aircraft certification process.”

Elwell is also expected to testify Wednesday in front of a different Senate subcommittee at a hearing on aviation safety. This is the first time both Chao and Elwell will be appearing before Congress since the crash of Ethiopian Airlines Flight 302 earlier this month.

The FAA certified the Boeing 737 Max jet in 2017 and let it keep flying after a deadly crash in October in Indonesia that investigators believe may be related to a new flight-control system that pushed the plane’s nose down repeatedly. Following the second fatal 737 Max crash in Ethiopia, regulators around the world grounded all Max jets.

Preliminary satellite data indicates that both doomed planes made erratic climbs and descents before crashing shortly after takeoff. It’s likely to be months before investigators in Indonesia and Ethiopia issue conclusions on what caused the accidents.

Boeing has said it is making changes to its software on the Max. The company announced it would now make standard an indicator light that warns pilots of a sensor malfunction that could cause its anti-stall system to activate unnecessarily.

Investigators believe that anti-stall system, new on the 737 Max, triggered on Lion Air flight 610, repeatedly forcing down the nose of the plane, leading to last October’s crash into the Java Sea.

The previously optional indicator light was not installed on the Lion Air plane that crashed, or on Ethiopian Airlines flight 302, which went down under similar circumstances on March 10.

A U.S. airline source said that feature would cost roughly $80,000 extra on a plane with a list price of about $120 million.

Separately, in another sign Boeing is preparing to release its software updates for the grounded 737 Max, the company notified Max owners to sign up for and place orders for the software update, so it can be delivered once the update is approved.

Boeing vice president of communications Gordon Johndroe said in a statement that Max owners must “place a free of charge order through our standard orders system.” He added, “The update will only be released on certification but placing an order is a standard step to start the delivery process for any software or hardware change.”

With some airlines cancelling orders for 737 Max jets, business is booming for Boeing rival Airbus. The European airplane manufacturer has made a deal to sell 300 of its jetliners to state-owned airlines in China. At list prices, the deal could be worth $35 billion, but customers usually get big price discounts on orders of this size.

(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)