(Bloomberg) -- Boeing Co. withdrew a request for a key safety exemption meant to speed approval of its coming 737 Max 7 aircraft, bending to a chorus of pressure on the planemaker to prioritize safety in the wake of a near-catastrophe on one of its jets. 

The company’s retreat on the waiver tied to a de-icing system comes days after Democratic Senator Tammy Duckworth called on the Federal Aviation Administration to reject the Boeing’s petition for a time-limited exemption for the yet-to-be certified Max 7.

The US planemaker now plans to build the engine inlet de-icing feature during the certification process, Boeing said in a statement late Monday — an undertaking that could delay the jet’s entry into service.

“The FAA will determine the timing of certification and we will follow their lead every step of the way,” Boeing said. “We’re committed to being transparent, listening to all our stakeholders and taking action to strengthen safety and quality.”

The decision illustrates just one of the challenges ahead for Boeing as regulators pore over its manufacturing processes and pressure management to improve the quality of its planes. The setback is likely to extend the timeline for clearing the smallest version of Boeing’s cash-cow narrowbody, aiding rivals Airbus SE and Embraer SA. 

The same issue is likely to affect the coming Max 10, a larger version of the 737 that is not as far along as the Max 7 in the certification process.

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Duckworth, who chairs the Senate subcommittee on aviation safety, said in a Jan. 24 letter to FAA Administrator Michael Whitaker that “Boeing forfeited the benefit of the doubt long ago when it comes to trusting its promises about the safety of 737 Max.” 

The first of the four versions, the Max 8, was grounded for about 20 months after two fatal crashes in 2018 and 2019.

The blowout of a fuselage panel on Alaska Airlines Flight 1282 earlier this month led the FAA to ground Max 9 jets with the same door-plug feature. While the stop has since been lifted, Max 9 operators Alaska Air Group Inc. and United Airlines Holdings Inc. have criticized Boeing, as has Southwest Airlines Co., the launch customer for the Max 7. 

Boeing shares fell 2.4% at 1:16 p.m. in New York. They have declined 23% this year, the worst performance by far among members of the Dow Jones Industrial Average.  

Customer Delays

Some analysts now expect further delays to the Max 7 and the stretched Max 10, the final two 737 variants. Bloomberg has reported that United is looking for ways to get out of its contract for the Max 10, which will be the biggest Boeing single-aisle, and at least partially switch over to Airbus.

The core Max 8 and the Max 9 are both flying with what Duckworth termed the “same anti-ice system defect.” In her letter, she said Boeing won’t be able to implement a fix until 2026. Airlines had expected certification as soon as this year. 

Attempting to put the Max 7 into service before a permanent solution to the de-icing issue is in place “suggests the company has yet to learn the most basic lesson from its terrible 737 Max history: safety must come before profit,” Duckworth said. 

Southwest said on a conference call last week that its 2024 fleet plans do not include any Max 7 deliveries. 

The airline’s chief executive officer, Robert Jordan, said then that he’s spoken with Boeing leadership to make sure “they understand our feelings,” and that the airline supports the planemaker’s efforts to improve.

“The quality issue is a must, improving safety is a must, and becoming a better company is a must,” he said in an interview.

--With assistance from Mary Schlangenstein.

(Updates with detail on Max 10, updates shares)

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