Aircraft manufacturer Boeing has another investigative hearing to answer for after the dramatic incident that took place earlier this year when a door panel blew off an Alaska Airlines plane.

The National Transportation Safety Board — an independent investigative agency in the U.S. — says it will hold a hearing on Aug. 6 and 7 to determine why a door plug went missing from a Boeing 737-9 MAX passenger jet mid-flight.

The investigative hearing will help the board glean more information about the circumstances of the incident and make related safety recommendations. The hearing is open to the public, but only those scheduled to appear are allowed to participate.

Eight people incurred minor injuries during the Jan. 5 incident on a plane departing Portland, Oregon.

The flight, en route to Ontario, California, was forced to return to Portland when the plane experienced a rapid decompression. It had 171 passengers and six crew members aboard.

This comes days after the Department of Justice announced it was launching a criminal investigation into the same incident. Boeing has already said in a letter to congress that it hasn’t been able to find records of work done on the specific panel that blew off mid-flight.

With files from the Associated Press.