Date:	Tuesday 16 May 2023
Time:	14:45 LT
Type:	Diamond DA40NG Diamond Star
Owner/operator:	Twinstar4Hire Ltd
Registration:	G-LDGB
MSN:	40N296
Fatalities:	Fatalities: 0 / Occupants: 3
Other fatalities:	0
Aircraft damage:	Substantial
Location:	3 nm North West of Oxford-Kidlington Airport, Oxfordshire -   United Kingdom
Phase:	En route
Nature:	Training
Departure airport:	Oxford-Kidlington Airport (OXF/EGTK)
Destination airport:	Oxford-Kidlington Airport (OXF/EGTK)

Narrative:
AAIB investigation into Diamond DA40NG Diamond Star, G-LDGB: Rear passenger door detached from aircraft in flight, 3 nautical miles north-west of Oxford-Kidlington Airport, 16 May 2023. The incident was the subject of an AAIB Investigation, and the final report was published on 12 December 2024. The following is an excerpt from the AAIB Report:

"Synopsis
Whilst conducting an instrument flying training lesson the rear door detached from the aircraft. The instructor inadvertently disengaged the primary locking mechanism whilst pressing the rear door handle to demonstrate to students how to secure it in the event of an in-flight Primary Flying Display (PFD) door warning. The aircraft landed safely and there were no injuries. The Operator undertook a number of safety actions following the event.

History of the Flight
The flight was an instrument flight training lesson, there was also a passenger, another student, who was to observe for local area familiarity and lesson content. Part of the Operator’s checklist for the Diamond DA40 NG requires that the rear door is to be confirmed closed before engine start and before take-off. On both occasions the student pilot and the instructor observed the student in the rear seat check that the handle mechanism of the rear door was in place and apply pressure to the door; all crew members were content the rear door was locked. Furthermore, the door warning light was confirmed to be off on the PFD as required the aircraft checklist

Following a successful take-off and initial departure by the student, control was handed over to the instructor during climb out to enable the student to don the instrument flying hood, control was then returned to the student.

Prompted by a routine altitude warning and call out by the student pilot during the climb out, a discussion commenced with the instructor about visual and audio warnings on the PFD. The instructor demonstrated how selecting the pitot heat on would be displayed on the PFD.

There then followed a discussion about the most common occurrence being door warnings and how these can be triggered by the door handle being open a small amount. At this point the instructor reached back and pushed on the rear door handle to demonstrate to the students how to secure the door following an in-flight PFD warning that would indicate the door was not closed. As the instructor interacted with the door handle it unexpectedly opened fully.

With the student pilot still flying, the instructor and rear seat student assessed the situation. The rear seat passenger could not reach the door to close it due to the seat restraint harnesses and shortly afterwards the door fully detached from the airframe. The instructor took control of the aircraft, contacted ATC to advise of the situation and was given clearance to land. The return to the airfield, landing and taxi were uneventful and there were no injuries to the occupants."

The AAIB description of the incident would place G-LDGB in the vicinity of Book Hill, Woodstock, Oxfordshire (which is 3 miles from Kidlington via Oxford Street/A44 and Woodstock Road/A44). The AAIB Report does not state if the detached door was ever found or recovered.

AAIB Conclusion
The passenger door detached from the aircraft because the primary locking mechanism for the door was inadvertently disengaged by the instructor whilst demonstrating to the student pilot how to respond to potential door warnings in flight. The reason why the secondary mechanism that was designed to help prevent door opening in-flight did not retain the door could not be positively determined.

Safety actions
Following the accident, the operator undertook a number of safety actions:
● Providing clear guidance to crews on the use of the rear door and latches.
● Amendments to the pre-flight check list to include additional testing of the secondary latch during pre-flight checks and a reminder of the importance of reporting any faulty secondary latches as a defect.

Damage Sustained to airframe
Per the AAIB report "Rear passenger door detached from airframe". According to the AirNav RadarBox website (see link #3) the aircraft was repaired and returned to service

1. AAIB Final Report 12 December 2024: https://assets.publishing.service.gov.uk/media/67585f55e677f284d6cfc95c/AAIB_Bulletin_12-2024.pdf p.87
2. https://www.planelogger.com/Aircraft/Registration/G-LDGB/932685
3. https://airport-data.com/aircraft/G-LDGB.html
4. https://airport-data.com/aircraft/LN-FTP.html
5. https://www.radarbox.com/data/registration/G-LDGB
6. https://www.flightradar24.com/data/aircraft/g-ldgb
7. https://planefinder.net/data/aircraft/G-LDGB
8. Previous incident at Welshpool 11 October 2022 (ASN Report): https://asn.flightsafety.org/wikibase/308178
9. https://en.wikipedia.org/wiki/Oxford_Airport
10. https://en.wikipedia.org/wiki/Woodstock,_Oxfordshire

This Diamond DA40NG Diamond Star was built in 2015, and previously registered in Norway as LN-FTP to Sky Management A/s on 9 October 2015. The aircraft was first UK registered as G-LDGB on 8 January 2020 to Twinstar4Hire Ltd, the one and only owner to date.

The same aircraft was also involved in an incident at Mid Wales Airport, near Welshpool, Powys, Wales on 11 October 2022 (see link #8 and separate ASN entry). G-LDGB has accumulated a total of 6,048 flying hours as at 23 August 2024.

G-LDGB: Diamond DA 40NG of Leading-Edge Aviation at Oxford Kidlington 09/06/20.

Date/time	Contributor	Updates
16-Jun-2024 06:53	Dr. John Smith	Added
13-Dec-2024 10:30	Dr. John Smith	Updated [Time, Total occupants, Location, Nature, Destination airport, Source, Embed code, Narrative, ]