Washington CNN  —  Boeing is expected to release a plan this week to fix its endless string of safety issues that have been under federal investigation following a midflight fuselage blowout in January. The report is a critical step for Boeing to rebuild confidence among the public, airlines, and its regulator that it can build safe airplanes after its reputation has been severely damaged by accidents, probes and whistleblower claims of shortcuts and retaliation. The plans may also reveal what Federal Aviation Administration inspectors found when auditing Boeing and key supplier Spirit AeroSystems factories earlier this year. The FAA said it shared the findings with the two companies, but it has refused to make the report public so far. In this March 14, 2019, file photo, a worker walks next to a Boeing 737 MAX 8 airplane parked at Boeing Field in Seattle. Boeing said Thursday, July 18, it will take a $4.9 billion charge to cover possible compensation to airlines whose Max jets remain grounded after two deadly accidents. Ted S. Warren/AP Related article Boeing timeline: Inside the air giant’s turbulent journey in recent years In late February, the FAA gave the planemaker and its outgoing chief executive 90 days to develop the plan and said it would not approve any Boeing request to expand Max production in the meantime. Since then, the FAA and Boeing have met multiple times about the company’s progress and the plan’s scope. FAA Administrator Mike Whitaker said last week he sees the plan as only the “beginning” of a process for Boeing. “It’s going to be a long road to get back to where they need to be making safe airplanes,” Whitaker said in an ABC News interview. Years of safety issues This latest generation of Boeing’s 737 first came under scrutiny when two Max planes crashed in 2018 and 2019, killing 346 people. Multiple international and US investigations focused on a stabilization system called MCAS that pilots were not properly informed of. Boeing later agreed to financial penalties and a deferred prosecution agreement to settle a criminal charge of defrauding US regulators. Since then, successive issues with the Max and other aircraft – including the 787 Dreamliner, the 777 and the future Air Force One jet – have cost the company billions. The latest wave of reviews began in January, when a door plug blew out of a 737 Max 9 in-flight. Video shot by passengers on Alaska Airlines flight 1282 showed a gaping hole in the side of the aircraft as it urgently returned to the Portland, Oregon airport. The door plug later turned up in the brush of a schoolteacher’s backyard. The FAA grounded Max 9s for three weeks and required each door plug undergo inspection. National Transportation Safety Board investigators believe the plane left Boeing’s factory last fall without critical bolts to hold the wall piece in place. Boeing CEO Dave Calhoun admitted to a “quality escape” and later said he would join several other top officials by stepping down from the company this year. So significant have been the company’s ongoing safety problems that the Department of Justice earlier this month said that Boeing had breached the terms of its deferred prosecution agreement over the 737 Max charge, meaning the company could be prosecuted over those incidents after all. The FAA also deployed auditors to the Wichita, Kansas, Spirit AeroSystems factory that builds the Max fuselage and the Renton, Washington, facility that finishes assembling the aircraft. The inspection found “multiple instances where the companies allegedly failed to comply with manufacturing quality control requirements.” Boeing 737 MAX airplanes are seen after leaving the assembly line at a Boeing facility on August 13, 2019 in Renton, Washington. David Ryder/Getty Images But precisely what those failures are remains unclear. Whitaker, the FAA administrator, said in March the shortcomings reflect processes that are “really important in a factory.” The agency has told CNN they cannot make the report public because it is “part of an ongoing investigation.” Then came the findings of an expert panel commissioned prior to the blowout that found gaps in Boeing’s safety culture. Employees feared retaliation for raising concerns and did not understand their role in producing safe airplanes, the panel of FAA officials and outside experts found. When the company stopped production for a day and polled its workers for potential safety improvements, ideas flooded in. Boeing said the internal tip line received 500 percent more reports in the first few months of this year compared to last year. In the meantime, Boeing said it has made immediate changes to improve quality. The company has cracked down on out-of-order assembly line work, improved production line instructions, purchased additional tools for workstations and ordered Spirit AeroSystems to wait until fuselages are complete before sending them to Boeing. “Once they get to our factory, rework is lower, flow time is better, traveled work is less,” Boeing Chief Financial Officer Brian West said at an industry conference last week.“We’re not declaring victory, but we know this was the right move, and we’ll begin to reap the benefits.” While investigations into the door plug incident continue, and while the prospect of a criminal trial hangs over Boeing, the company will have a new plan for improvements. Its marching orders for the plan include addressing the audit and expert panel findings and explaining how it will integrate safety and quality assurance policies into practice.