Just as it was looking like the Federal Aviation Administration (FAA) was getting close to ending the eight-month grounding of the Boeing 737 MAX, the head of the U.S. House Transportation Committee is raising what he says are new issues.

Rep. Peter DeFazio, who presided over a tough hearing for Boeing CEO Dennis Muilenburg last week, said a whistleblower brought two issues to the committee’s attention which he calls potentially catastrophic.

The 737 MAX related issue involves rudder cable protection from an uncontained engine failure. An uncontained engine failure is when parts breakthrough protective barriers on the engines, often into the fuselage.

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In a news release, DeFazio cites a 2014 FAA memo that Boeing had not adequately protected the 737 MAX rudder cable as required, as the track record of the new larger LEAP 1B engines had not had a proven track record.

In a second issue, DeFazio raises questions about lightning protection for Boeing 787 fuel tanks. That concern involves approximately 40 airplanes delivered before FAA approval of a design change.

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Boeing issued the following statement Thursday afternoon:

“We are aware of both issues raised in Chairman DeFazio’s letter. We are confident that each was properly considered and addressed by Boeing, thoroughly reviewed with and approved by the FAA, and handled in full compliance with the processes governing review and disposition of such issues — processes that have led to continuous improvement in aviation safety.”