What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
(-23) Rexa FLG5966 returned to Omaha due to an open oxygen panel located on the exterior of the fuselage below the first officer side window. No emergency declared and no special handling. Aircraft did several fly arounds until the aircraft was at landing weight. Aircraft landed without incident. It appears a flight crew member failed to secure the door during pre-flight.
As the FAA filed it
(-23) REXA FLG5966 RETURNED TO OMAHA DUE TO AN OPEN OXYGEN PANEL LOCATED ON THE EXTERIOR OF THE FUSELAGE BELOW THE FIRST OFFICER SIDE WINDOW. NO EMERGENCY DECLARED AND NO SPECIAL HANDLING. AIRCRAFT DID SEVERAL FLY AROUNDS UNTIL THE AIRCRAFT WAS AT LANDING WEIGHT. AIRCRAFT LANDED WITHOUT INCIDENT. IT APPEARS A FLIGHT CREW MEMBER FAILED TO SECURE THE DOOR DURING PRE-FLIGHT.