In a recent report released by the U.S. safety board investigating the incident, it has been revealed that a door panel that flew off a Boeing 737 MAX 9 jet mid-flight on January 5th was missing four key bolts. This incident has caused a major safety and reputational crisis for Boeing, potentially leading to a slowdown in plane production and a loss of market share to its rival, Airbus.

The National Transportation Safety Board (NTSB) has been conducting an investigation to determine the cause of the panel detachment. The report states that the investigation is ongoing to determine which manufacturing documents were used to authorize the opening and closing of the plug during the rivet rework. The plug had been removed to fix damaged rivets that occurred during the production process.

Photo evidence released on Tuesday clearly shows that bolts were missing from the door plug. The plug is held down by four bolts and secured by "stop fittings" at 12 different locations along the side of the plug and the door frame. During the incident, all 12 stop fittings became disengaged, causing the panel to detach from the plane.

Following the incident, the Federal Aviation Administration (FAA) grounded 171 Boeing 737 MAX 9 planes, most of which were operated by U.S. carriers United and Alaska Airlines, for inspections. These planes were eventually cleared to return to service in late January. Both United Airlines and Alaska Air reported finding loose parts on multiple grounded MAX 9 aircraft in the aftermath of the incident.

The door panel in question was manufactured by Spirit AeroSystems, a onetime subsidiary of Boeing that separated from its parent company in 2005. The production process involves work at Spirit AeroSystems' facility in Wichita, Kansas, before the plane bodies are transported to Boeing's plant in Renton, Washington.

This incident has further strained the relationship between Boeing and the FAA. In late January, the FAA took a tougher stance and barred Boeing from expanding production of its 737 MAX planes due to quality issues. The FAA's stricter approach is seen as a response to the series of safety concerns surrounding the Boeing 737 MAX, including the two fatal crashes in 2018 and 2019.

Boeing is now facing the challenge of addressing these safety concerns and rebuilding its reputation in the aviation industry. The investigation into the missing bolts and the subsequent panel detachment will be crucial in determining the root cause of the incident and implementing necessary corrective measures to prevent similar incidents in the future.