A DA40F on a cross country training flight lost the aircraft door and diverted to nearest airport.

Attributes
ACN	718461
Time
Date	200611
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 8500
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	general aviation : instructional
Make Model Name	Small Aircraft Low Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Plan	VFR
Aircraft 2
Navigation In Use	other
Flight Phase	cruise : level
Person 1
Affiliation	company other
Function	instruction : instructor
Qualification	pilot : multi engine pilot : commercial pilot : cfi pilot : instrument
Experience	flight time last 90 days : 110 flight time total : 425 flight time type : 95
ASRS Report	718461
Person 2
Affiliation	other
Function	instruction : trainee
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : diverted to another airport
Consequence	other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Ambiguous

Narrative:

A student and I were on a night cross country flight. We had set up a cruise flight and decided to open the flight plan and amended the departure time from XA00 to XA41. We were about 10 miles to the northwest of ZZZ when I noticed a breeze. So I checked all of the vents in the plane to make sure they were closed. I looked and noticed that the door was no longer closed all the way. I inspected visually the door latch and noticed that it was secured properly. But the door was not down all of the way. I saw the door pop open more and tried to grab it; but just before I touched the door; it gave and the door was immediately ripped clear off the plane. I contacted local radio and informed them that we were going to fly direct to ZZZ1 and wanted the flight plan closed. He said he wanted to open a flight plan to ZZZ1 for us and asked for our ETA. After computing our ETA on the G1000 for a direct to ZZZ1 I told him it would be about 13 minutes. He said to make sure that we contacted him upon arrival and they would keep an eye out for us. We returned back to ZZZ1 and had another flight instructor follow us back to the airport to make sure that we made it safely. The rest of the flight was -12 degrees and cold; but luckily; uneventful. It looked like the door was a pretty clean break right at the hinges. We looked at two other diamonds and noticed that the hinges looked like they might have cracks on them also.callback conversation with reporter revealed the following information: reporter states the door was found recently and inspection revealed the aft locking pin had come adrift and was found within the door itself. There is no warning light associated with the aft pin; unlike the forward pin which; if not locked; would illuminate the master caution light. Reporter's employer; a flight school; is in contact with manufacturer and is inspecting the balance of their fleet to determine if other potential problems exist.

Original NASA ASRS Text

Title: A DA40F ON A XCOUNTRY TRAINING FLT LOST THE ACFT DOOR AND DIVERTED TO NEAREST ARPT.

Narrative: A STUDENT AND I WERE ON A NIGHT XCOUNTRY FLT. WE HAD SET UP A CRUISE FLT AND DECIDED TO OPEN THE FLT PLAN AND AMENDED THE DEP TIME FROM XA00 TO XA41. WE WERE ABOUT 10 MILES TO THE NW OF ZZZ WHEN I NOTICED A BREEZE. SO I CHKED ALL OF THE VENTS IN THE PLANE TO MAKE SURE THEY WERE CLOSED. I LOOKED AND NOTICED THAT THE DOOR WAS NO LONGER CLOSED ALL THE WAY. I INSPECTED VISUALLY THE DOOR LATCH AND NOTICED THAT IT WAS SECURED PROPERLY. BUT THE DOOR WAS NOT DOWN ALL OF THE WAY. I SAW THE DOOR POP OPEN MORE AND TRIED TO GRAB IT; BUT JUST BEFORE I TOUCHED THE DOOR; IT GAVE AND THE DOOR WAS IMMEDIATELY RIPPED CLEAR OFF THE PLANE. I CONTACTED LOCAL RADIO AND INFORMED THEM THAT WE WERE GOING TO FLY DIRECT TO ZZZ1 AND WANTED THE FLT PLAN CLOSED. HE SAID HE WANTED TO OPEN A FLT PLAN TO ZZZ1 FOR US AND ASKED FOR OUR ETA. AFTER COMPUTING OUR ETA ON THE G1000 FOR A DIRECT TO ZZZ1 I TOLD HIM IT WOULD BE ABOUT 13 MINUTES. HE SAID TO MAKE SURE THAT WE CONTACTED HIM UPON ARR AND THEY WOULD KEEP AN EYE OUT FOR US. WE RETURNED BACK TO ZZZ1 AND HAD ANOTHER FLT INSTRUCTOR FOLLOW US BACK TO THE ARPT TO MAKE SURE THAT WE MADE IT SAFELY. THE REST OF THE FLT WAS -12 DEGS AND COLD; BUT LUCKILY; UNEVENTFUL. IT LOOKED LIKE THE DOOR WAS A PRETTY CLEAN BREAK RIGHT AT THE HINGES. WE LOOKED AT TWO OTHER DIAMONDS AND NOTICED THAT THE HINGES LOOKED LIKE THEY MIGHT HAVE CRACKS ON THEM ALSO.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THE DOOR WAS FOUND RECENTLY AND INSPECTION REVEALED THE AFT LOCKING PIN HAD COME ADRIFT AND WAS FOUND WITHIN THE DOOR ITSELF. THERE IS NO WARNING LIGHT ASSOCIATED WITH THE AFT PIN; UNLIKE THE FORWARD PIN WHICH; IF NOT LOCKED; WOULD ILLUMINATE THE MASTER CAUTION LIGHT. RPTR'S EMPLOYER; A FLT SCHOOL; IS IN CONTACT WITH MANUFACTURER AND IS INSPECTING THE BALANCE OF THEIR FLEET TO DETERMINE IF OTHER POTENTIAL PROBS EXIST.

Data retrieved from NASA's ASRS site as of January 2009 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.