Date:	Wednesday 23 June 2021
Time:	13:37 UTC
Type:	Grob G-102 Astir 77 CS
Owner/operator:	Trustee of the Sierra Kilo Group
Registration:	G-CJSK
MSN:	1521
Year of manufacture:	1977
Fatalities:	Fatalities: 0 / Occupants: 1
Aircraft damage:	Destroyed
Category:	Accident
Location:	Gibbett Hill, Brentor, near Tavistock, Devon -   United Kingdom
Phase:	En route
Nature:	Private
Departure airport:	Bodmin Airport (EGLA)
Destination airport:
Investigating agency:	AAIB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
Grob G-102 Astir 77 CS crashed 23.6.2021 in the Blackdown Hills above Broadhembury, Five miles to the east of Cullompton, and five miles to the north-west of Honiton, Devon.

The right aileron L’Hotellier control connection in the fuselage became disconnected in flight, causing the pilot to abandon the glider by parachute. The control connection was equipped with a secondary Wedekind sleeve locking device, and the pilot had conducted a positive control check to his satisfaction prior to the accident flight. The investigation demonstrated that it is possible to partially assemble this type of control connection such that the connection is not secure, despite appearing to be so during a positive control check. The BGA has provided guidance to affected aircraft owners on how to inspect this type of control connection to ensure that it is secure, following glider assembly.

The pilot launched by winch from Bodmin Airfield at 12:50 hrs and climbed to an altitude of 4,100 ft for local soaring. After flying for approximately 50 minutes the pilot heard a metallic noise from behind him and he noticed that the ailerons felt less responsive than normal. He observed that some left aileron input was required to maintain straight and level flight, and that the right aileron was not responding to control inputs. The glider was traversing an area of sinking air and as the pilot increased speed to 55 kt the wings began to flutter from the airbrakes out to the wingtip. The pilot reduced airspeed and the flutter stopped.

The pilot flew back towards the airfield whilst assessing the degree of control he had over the glider. He tried some ‘S’ turns and found it difficult to fly smooth turns, and as the airspeed increased above 55 kt the wings started fluttering again, shaking the whole airframe. He considered that he had insufficient control over the glider’s flightpath to safely land and therefore parachuted from the glider at an altitude he estimated to be between 1,500 to 2,000 ft, having ensured that he was over an uninhabited open area.

As the parachute canopy opened the harness was dragged past the pilot’s ears causing minor lacerations. The pilot described the parachute landing as heavy, causing minor bruising but no serious injury.

The glider came to earth, inverted, approximately 1 mile north northeast of Bodmin Airfield, Bodmin, Cornwall.

=Safety action=
The BGA has informed all owners of UK-registered sailplanes equipped with L’Hotellier control connections of the findings of its safety investigation. The safety information included guidance on how to physically check that Wedekind sleeves, where installed, are correctly locked by the application of a gentle pulling force on the socket, away from the ball. The BGA also published a video containing similar safety information.

Further safety information relating to the security of sailplane control connections is contained in EASA Safety Information Bulletin 2019-076

=Damage Sustained to airframe=
Per the above AAIB report "Aircraft Destroyed". G-CJSK was ex-BGA4742 (built in 1977) which became G-CJSK on 22.12.2007, and the registration was cancelled by the CAA (and the airframe de-registered) as "destroyed" on 23.8.2021"

1. BFU Germany Accident Report BFU21-0474-DX at https://www.bfu-web.de/DE/Publikationen/Bulletins/2021/Bulletin2021-06.pdf?__blob=publicationFile (p.17)
2. https://assets.publishing.service.gov.uk/media/618a96f6e90e07198018fb4a/Grob_G102_Astir_CS_G-CJSK_12-21.pdf
3. https://www.bbc.co.uk/news/uk-england-devon-59607149
4. https://www.legendarydartmoor.co.uk/dartmoors-gibbet-hill.htm
5. https://www.airport-data.com/aircraft/G-CJSK.html

Grob G-102 Astir 77 CS G-CJSK upside down approximately 1 mile north northeast of Bodmin Airfield, Bodmin, Cornwall 23 June 2021 (top right picture)

AAIB December Bulletin now publishedhttps://t.co/a5ML1GcqwA pic.twitter.com/dP8e1aBK2v

— AAIB (@aaibgovuk) December 9, 2021

Date/time	Contributor	Updates
11-Sep-2021 12:50	ASN archive	Added
11-Sep-2021 15:34	Dr. John Smith	Updated [Operator, Location, Phase, Nature, Departure airport, Destination airport, Source, Narrative, Category]
09-Dec-2021 22:48	Dr. John Smith	Updated [Time, Registration, Cn, Operator, Location, Source, Embed code, Narrative, Category]
09-Dec-2021 22:55	Dr. John Smith	Updated [Departure airport, Destination airport, Source, Embed code, Narrative]
10-Dec-2021 20:38	harro	Updated [Narrative, Accident report]
14-Dec-2021 19:33	Dr. John Smith	Updated [Source, Category]
12-Feb-2022 19:55	Dr. John Smith	Updated [Source]