Pilot Debrief

Glaser Dirks DG500 near Marana, AZ — 2019-10-06

Final reportWPR20LA004
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Date
2019-10-06
Location
Marana, AZ, USA
Airport
AZ67
Aircraft
Glaser Dirks DG500
Registration
N600TT
Category
Glider
Highest injury
Minor
Fatalities
0
Phase of flight
Maneuvering

Probable cause

The pilots’ exceedance of the glider’s never-exceed speed (VNE) during recovery from an intentional aerobatic maneuver, which resulted in a failure of the right-wing air brake control drive, asymmetrical air brake deployment, and a subsequent hard landing.

NTSB narrative

The pilots were performing aerobatic maneuvers in the glider. While recovering from a maneuver, the glider’s airspeed increased past the never-exceed speed (Vne) and the elevator began to flutter. The right air brake (spoiler) deployed fully, though the spoiler control was in the locked position. After assessing the controllability of the glider, the pilots chose to land at the gliderport rather than perform an emergency egress. The glider landed hard and impacted brush, resulting in the separation of the empennage at the tailboom. Postaccident examination revealed a separation of the right-wing air brake control drive system at the rod end, which resulted in the asymmetrical spoiler extension. The manufacturer stated that it should have been possible to deploy the left-wing air brake normally to compensate for the asymmetric behavior and have some (reduced) control over the approach glidepath. The manufacturer also stated there is no emergency procedure described in the flight manual for air brake malfunctions. It is likely that the air brake control separation was the result of the pilots’ exceedance of Vne during recovery from the aerobatic maneuver.

Analysis

Primary failure mode
Human factors
First missed decision gate
Front seat pilot could have aborted the maneuver before stall occurred.

NTSB coding

Evidence available

  • Photos
  • 6 docket documents
View NTSB final reportView NTSB docket

Docket documents6

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