Pressure from Sen. Tammy Duckworth (D-Ill.) led Boeing this week to withdraw a request with the FAA for a safety standard exemption for the 737 Max 7 aircraft, which has yet to be certified.
Boeing had requested an exemption to be able to fly the Max 7 while it continued to work on an engineering fix for the aircraft's engine inlet de-icing system.
In a Jan. 24 letter to FAA administrator Michael Whitaker, Duckworth argued that with the design flaw, the de-icing system could overheat, which in turn could cause the engine cover to break off.
"This could generate fuselage-penetrating debris, which could endanger passengers in window seats behind the wing and/or result in a loss of control of the aircraft," she wrote.
Boeing, already under scrutiny after near-catastrophic blowout of an exit door plug on an Alaska Airlines Boeing 737-9 plane in early January, quickly put Duckworth's concerns to rest. Boeing now says it expects to develop the engineering fix within a year, but won't pursue the exemption.
Speaking on Boeing's fourth quarter earnings call this week, CEO Dave Calhoun said he was persuaded by Duckworth's reasoning when the two met last week in Washington, D.C. Duckworth was a helicopter pilot in the Iraq war.
"It was a sound and principled position to take," he said.
Southwest Airlines is the launch partner for the Max 7, which will be the smallest version of Boeing's narrowbody Max series. The carrier has 307 firm Max 7 orders through 2031, and as of last week still had 27 Max 7s on its schedule for delivery this year.
However, Southwest also said last week that it had removed the aircraft from its flight planning for 2024. The airline plans to grow by 6% this year, without Max 7 planes.
The already-certified Boeing Max 8s and Max 9s also have the de-icing system design flaw. The FAA has granted an exemption that allow those planes to continue flying until an engineering fix is implemented.