'Felt As If The Empennage Was Rocking/Twisting From Side-To-Side'

Location: Giddings, TX Accident Number: CEN23LA405
Date & Time: September 7, 2023, 16:25 Local Registration: N321AD
Aircraft: Alisport SRL Silent 2 Electro Injuries: 1 None
Flight Conducted Under: Part 91: General aviation - Personal

On September 7, 2023, at 1625 central daylight time, a Alisport SRL Silent 2 Electro, N321AD, was involved in an accident near Giddings, Texas. The pilot was uninjured. The glider was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. 

The pilot stated that the glider was in normal straight-ahead cruise flight at approximately 81 kts and 4,800 ft when the cockpit began to shake violently and noisily side-to-side. He said it felt as if the empennage was rocking/twisting from side-to-side. He said there were no unusual conditions and no significant control inputs prior to the shaking, which lasted about 10-15 seconds. The maximum speed of the glider during the occurrence was 90 kts and slowed to about 60 kts toward the end of the shaking. There was an associated altitude loss of about 300 ft. Once the shaking ceased, the glider felt controllable, and the pilot returned to the departure airport without further incident.

The glider sustained substantial damage due to cracks within the composite structure of the fuselage that were about 1-3 feet forward of the empennage. 

The glider was retained for further examination.

FMI: www.ntsb.gov