ERA23LA013 · Schempp-Hirth DISCUS CS
Skyline Soaring Club Schempp-Hirth DISCUS CS · Accident: part(s) separation from aircraft en route
From Front Royal Warren County Airport (FRR) to an unrecorded destination
Event
- NTSB case
- ERA23LA013
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Schempp-Hirth DISCUS CS
- Aircraft type
- Schempp Hirth DISCUS CS
- Category
- Glider
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N520RJ
- Operator
- Skyline Soaring Club
- Onboard fatalities
- Unknown
- Route
- From Front Royal Warren County Airport (FRR), Front Royal, VATo not recorded
- Aircraft age
- About 26 years (built 1996)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Part(s) separation from aircraft
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft structures
- Personnel issues › Task performance
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The pilot reported that the glider was at 3,700 ft mean sea level when the canopy suddenly, without warning, separated from the glider. He subsequently landed uneventfully at his intended destination airport.
Review of maintenance records revealed that about 2 years before the accident, a maintenance facility stop-drilled a hole to correct a canopy crack at the rear hinge along the glide frame. Metallurgical examination revealed that the drilled hole appeared to halt progression of the original crack along its initial propagation direction. However, both the new primary separation crack and a secondary crack propagated from the hole in diametrically opposite directions, which suggests they likely developed due to a stress state along the same plane. Additionally, both cracks propagated from internal surface corners of the hole, indicating the corners likely acted as stress risers that facilitated crack initiation.
There was no approved method from the glider manufacturer to stop-drill a hole in plexiglass; however, manufacturer approval was not required as the glider was registered in the experimental category. The glider manufacturer stated that it was common practice for cracks in the plexiglass to be drilled-out to stop the crack progression as a temporary solution; however, for a proper repair, the canopy must be removed and re-glued.
The presence of multiple cracks propagating out of the same stress riser of the internal hole corner indicated that the specific hole drilled did not prevent subsequent progression of further cracking and the eventual separation of the canopy.
Probable cause
Improper repair of a crack by maintenance personnel, which resulted in a subsequent failure of the glider canopy.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ERA23LA013
- Event ID
- 20221010106089
- Case number
- ERA23LA013
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates, cause areas. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: d7f2d5adb1da403bb4a7b83510b0a9daf490fcedb5ad8b6b0f82cb487f519d2d; retrieved 2026-09-16T16:13:43.551Z.