In the wake of the recent in-air door plug blowout incident involving Alaska Airlines' 737-9 Max aircraft, Boeing is facing more safety issues as the Federal Aviation Administration (FAA) expands its oversight. The FAA is now recommending inspections of door plugs on Boeing 737-900ER aircraft, which share the same design as their MAX counterparts.

The FAA has issued a safety advisory, urging operators of the 737-900ER planes to visually inspect the mid-exit door plugs to ensure they are properly secured. The inspection is crucial to verify that the door plugs remain fastened by two upper guide track bolts and two lower arrestor bolts. The mid-flight door plug blowout incident on an Alaska Airlines 737-9 Max flight in January was attributed to the failure of the plug and restraining bolts.

The Boeing 737-900ER, the last variant of the 737-NG jet before the updated 737 Max, is currently in service with 490 planes flying worldwide. Among the key operators are Delta Air Lines, United Airlines, and Alaska Airlines.

While the 737-900ER aircraft will continue to be in service during the inspections, the latest FAA safety advisory serves as a reminder of the ongoing safety and reliability issues faced by Boeing and its door plug provider, Spirit AeroSystems. Both companies have experienced a decline in their stock values since the beginning of the year.

Since the incident with Alaska Airlines, Boeing has been working with the FAA to resolve the grounding of the 737-9 Max fleet in the United States. However, progress has been hindered by inadequate instructions provided by Boeing to airlines for inspecting the aircraft. Loose bolts were discovered in panels during inspections, prompting the FAA to stress that the safety of the flying public takes precedence over expediting the aircraft's return to service.

In response to these safety concerns, the FAA has increased its oversight of Boeing's production and manufacturing processes. An investigation is underway to determine whether Boeing failed to ensure compliance with FAA safety regulations and approved designs for their completed products.

Moreover, to address quality issues, Boeing has appointed retired Admiral Kirkland Donald of the US Navy as an independent adviser to conduct a comprehensive review of its commercial quality management system. This review includes an evaluation of practices at Boeing plants, as well as the company's oversight of supplier quality.

Following reports of alleged shortcuts in production practices by Spirit AeroSystems, the FAA expanded its investigation to include the manufacturing processes of both Boeing and Spirit AeroSystems. This move came after an alarming number of defects were reported.

During a recent visit to Spirit AeroSystems' facility in Wichita, Kansas, Boeing CEO Dave Calhoun emphasized the need for change. He expressed his commitment to improving collaboration between Boeing and Spirit AeroSystems, ensuring that engineers, mechanics, and inspectors from both companies communicate effectively.

As Boeing faces further scrutiny and works towards resolving safety concerns, the industry and the public remain focused on the implementation of effective measures to enhance the safety and reliability of Boeing aircraft.