The chief executive of Boeing insisted on Wednesday that the planemaker only allows jets to fly when “100%” confident of their safety, as it faces intense scrutiny – and anger – following a cabin panel blowout on an Alaska Airlines flight. Boeing fully understands “the gravity of the situation”, Dave Calhoun said in Washington, as he prepared to meet a string of US senators. His company has been trying to reassure airlines, regulators and passengers after a cabin panel blew off a brand-new 737 Max 9 jet during an Alaska flight earlier this month. About 171 Max 9 jets have since been grounded. “We don’t put planes in the air that we don’t have 100% confidence in,” Calhoun told reporters. As inspections continue, and officials continue to investigate what caused the incident, the Seattle Times reported on Wednesday that the fuselage panel that blew off the Alaska flight had been removed for repair and re-installed improperly by Boeing’s mechanics at its Renton final assembly line. Speaking with reporters, Calhoun referred a question about the report to the National Transportation Safety Board (NTSB), which did not comment. Calhoun is due to meet senators including Maria Cantwell, who chairs the Senate commerce committee, who plans to hold a hearing following the grounding of the Max 9 jets. Ted Cruz, the committee’s top Republican, is due to meet Calhoun on Thursday. The Federal Aviation Administration (FAA) said on Wednesday that it had approved an inspection and maintenance process to allow grounded Boeing 737 Max 9 planes to return to service, but would not allow any ramp up of Max production by the planemaker. The agency halted flights on 6 January following a mid-air emergency on an Alaska Airlines jet. “The exhaustive, enhanced review our team completed after several weeks of information gathering gives me and the FAA confidence to proceed to the inspection and maintenance phase,” FAA administrator Mike Whitaker said in a statement. The FAA said it would not grant any production expansion of Boeing’s bestselling Max narrowbody family of jets, including the 737 Max 9. Concern over the reliability of Boeing jets has strained the group’s relations with key airlines. Ben Minicucci, the chief executive of Alaska, said it had found “some loose bolts on many” Max 9 jets in its fleet. “I’m more than frustrated and disappointed,” he told NBC News. “I am angry.” United Airlines is weighing plans to leave an upcoming Boeing jet, the Max 10, out of its fleet. “I think the Max 9 grounding is probably the straw that broke the camel’s back for us,” Scott Kirby, its chief exceutive, told CNBC. For Boeing, this amounts to the biggest safety crisis since the crashes of two of its Max 8 jets, in 2018 and 2019, in which 346 people were killed. The 737 Max was subsequently grounded across the world for almost two years. Analysts have called into question whether executives at the company will have to resign. Officials “will likely look for more change from within Boeing”, Ronald Epstein of Bank of America wrote last week. “We would not be surprised to see regulators, investors and customers push for a turnover in the ranks of senior management and the board of directors.”