The Federal Aviation Administration said that the investigation is focusing on plugs on Boeing 737 Max 9 jetliners.
The US is investigating if Boeing ensured a part that blew off a jet was made to design standards::The Federal Aviation Administration said that the investigation is focusing on plugs on Boeing 737 Max 9 jetliners.
Here is the more burning question: What is worse?
Case "It was not made to design standards":
Then boing might have a problem in their manufacturing processes, which is going to have ramifications on the entire fleet. This would be bad, but fixable.
Case "It was made to design standards":
In that case you only have a problem with this one type of jet, but you have a problem in your fundamental design, which might ground the entire fleet (again).