Narrative:

Upon blocking in at the gate at our ZZZ hub, an FAA inspector presented credentials and motioned for the captain to exit the aircraft. He called to the captain's attention a missing lavatory service door. He asked if we had lavatory service at our point of departure (we had not). What must have happened was shortly before our last departure from ZZZ, ground personnel svced the lavatory and left the door open. This would be after my preflight/postflt inspection so not detectable by us. However, upon arrival at bwi, we must have missed the fact that the door was gone (ie, departed the aircraft en route) when postflt inspecting. We flew back to ZZZ where the FAA inspector just happened to be parked at our gate area doing spot inspections. He instructed us to write the discrepancy up in the aircraft log and fill out a company incident report.

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Original NASA ASRS Text

Title: A JETSTREAM 41 ON GATE ARR WAS DISCOVERED BY A FAA SAFETY INSPECTOR TO HAVE THE LAVATORY SVC DOOR MISSING. MISSING DOOR WAS NOT DISCOVERED BY THE FLC PREFLT CHK DOWNLINE.

Narrative: UPON BLOCKING IN AT THE GATE AT OUR ZZZ HUB, AN FAA INSPECTOR PRESENTED CREDENTIALS AND MOTIONED FOR THE CAPT TO EXIT THE ACFT. HE CALLED TO THE CAPT'S ATTN A MISSING LAVATORY SVC DOOR. HE ASKED IF WE HAD LAVATORY SVC AT OUR POINT OF DEP (WE HAD NOT). WHAT MUST HAVE HAPPENED WAS SHORTLY BEFORE OUR LAST DEP FROM ZZZ, GND PERSONNEL SVCED THE LAVATORY AND LEFT THE DOOR OPEN. THIS WOULD BE AFTER MY PREFLT/POSTFLT INSPECTION SO NOT DETECTABLE BY US. HOWEVER, UPON ARR AT BWI, WE MUST HAVE MISSED THE FACT THAT THE DOOR WAS GONE (IE, DEPARTED THE ACFT ENRTE) WHEN POSTFLT INSPECTING. WE FLEW BACK TO ZZZ WHERE THE FAA INSPECTOR JUST HAPPENED TO BE PARKED AT OUR GATE AREA DOING SPOT INSPECTIONS. HE INSTRUCTED US TO WRITE THE DISCREPANCY UP IN THE ACFT LOG AND FILL OUT A COMPANY INCIDENT RPT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.