Boeing has given airlines instructions on how to inspect their 737 Max 9 jetliners, a step toward ending the grounding of the planes, according to an internal message from company executives.

The Federal Aviation Administration ordered airlines to stop flying dozens of the jets over the weekend, less than a day after a door plug blew open during an Alaska Airlines flight as it was at 16,000 feet.

No one was seriously injured in the accident during Alaska Airlines Flight 1282, which was bound for Ontario, California, when the door plug blew, forcing it to return to Portland, Oregon, minutes into the flight.

It wasn’t immediately clear how long the inspections would take.

“Our teams have been working diligently – with thorough FAA review – to provide comprehensive, technical instructions to operators for the required inspections. This morning, our team issued the instructions via a multi-operator message,” said Boeing’s commercial airplanes president and CEO, Stan Deal, and its chief aerospace safety officer and senior vice president of global aerospace safety, Mike Delaney, in the internal message.

There are more than 200 737 Max 9 aircraft in fleets worldwide. United Airlines has a fleet of 79 737 Max 9s and Alaska Airlines has 65. The remainder are spread across other airlines.

“The FAA’s priority is always keeping Americans safe,” the agency said in a statement Monday. “In that spirit, Boeing 737-9 aircraft will remain grounded until operators complete enhanced inspections which include both left and right cabin door exit plugs, door components, and fasteners. Operators must also complete corrective action requirements based on findings from the inspections prior to bringing any aircraft back into service.”

Don’t miss these stories from CNBC PRO: