Software updates that Boeing Co. is readying for the 737 Max airliner should be cleared by an independent review before the beleaguered jet is allowed to fly again, the chairman of the House Transportation and Infrastructure Committee said Tuesday.

Oregon Democrat Peter DeFazio said the panel will send a bipartisan letter to the Federal Aviation Administration later on Tuesday requesting the agency bring on an independent, third-party to evaluate the proposed fix and ensure that pilots receive adequate information and training on the system.

“This all must be done before the 737 MAX is certified to return to service,” DeFazio said in a statement. “The traveling public needs assurances that the FAA will only re-certify the aircraft for flight if and when the FAA, outside safety and technical experts, and pilots agree the aircraft is safe to fly.”

Boeing is preparing software updates for anti-stall countermeasures on the 737 Max that investigators said in a preliminary report malfunctioned and repeatedly pushed a Max operated by Lion Air into a dive prior to crashing into the Java Sea near Indonesia in October. Authorities are also investigating whether the system was a factor in the March 10 crash of a 737 Max flown by Ethiopian Airlines, which regulators said behaved similarly to the earlier downed jet.

DeFazio’s call for an outside review of the changes comes amid mounting scrutiny from federal investigators and lawmakers alike into the FAA’s certification of the 737 Max.

DeFazio and Representative Rick Larsen, the Washington Democrat who chairs the panel’s aviation subcommittee and whose district includes Boeing’s campus in Everett, Washington, have begun their own probe into the agency’s safety approvals. They also have asked for a probe by the Transportation Department’s internal watchdog.

The Transportation Department is also forming a new committee to review how new aircraft are certified by FAA as safe to fly.