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ASN Wikibase Occurrence # 232534
Last updated: 18 February 2021
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Date:27-JAN-2020
Time:16:08 LT
Type:Silhouette image of generic DUOD model; specific model in this crash may look slightly different
Schempp-Hirth Duo Discus
Owner/operator:Armée de l’Air française
Registration: F-CFEY
C/n / msn: 191
Fatalities:Fatalities: 0 / Occupants: 2
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Category:Accident
Location:Salon-de-Provence Air Base, Bouches-du-Rhône -   France
Phase: En route
Nature:Training
Departure airport:Salon-de-Provence Air Base
Destination airport:Salon-de-Provence Air Base
Investigating agency: BEA-É
Narrative:
During a training mission northeast of Salon-de-Provence, the instructor of the Duo Discus performed a rapid descent to maintain regulatory weather conditions.
He attained a pitch-down attitude and then took out the speed brakes. When the instructor leveled off and tried to retract the airbrakes, they remain blocked in the extended position. He saw that the right airbrake presented an anomaly.
Although its range was very reduced with the airbrakes extended, they set a course towards the threshold of grass runway 16, while looking for an emergency landing zone on the way. No available space seemed adequate.
The glider approached the air base. The instructor noted that the glider's glide ratio was insufficient to reach the runway. He was forced to land the glider in a field about 500 meters before the runway. The glider slid on the ground then hit concrete blocks.
Both pilots are injured. The glider was destroyed.

Causes of the event
The Duo Discus is particularly sensitive to the blocking of the airbrakes in the extended position when extended at high speed in the flight envelope.
This defect is related to :
- a suction of the airbrakes in flight at a speed higher than 200 km/h, difficult to dampen with the force of the arms alone;
- an accumulation of play in the linkage which allows the deployment of the speed brakes until the last mechanical stop and cancels the overlap between the two panels;
- an important deformation of the panels composing the airbrakes, which can cross each other in an irreversible way in flight;
- an absence of airbrake adjustment procedure in the Duo Discus maintenance documentation;
- a lack of consideration by the manufacturer of this problem in view of the little information that has been provided to them.

Sources:

https://www.ouest-france.fr/provence-alpes-cote-dazur/salon-de-provence-13300/bouches-du-rhone-un-planeur-se-crashe-salon-de-provence-deux-blesses-6710543
https://www.laprovence.com/actu/en-direct/5864439/.html

Accident investigation:
cover
  
Investigating agency: BEA-É
Status: Investigation completed
Duration: 1 year
Download report: Final report
Location


Revision history:

Date/timeContributorUpdates
28-Jan-2020 11:11 gerard57 Added
29-Jan-2020 08:51 Iceman 29 Updated [Time, Operator, Location, Nature, Source, Narrative]
18-Feb-2021 18:42 harro Updated [Time, Registration, Cn, Location, Departure airport, Destination airport, Source, Narrative, Category, Accident report]
18-Feb-2021 18:45 harro Updated [Narrative]

Corrections or additions? ... Edit this accident description