SEA02LA003 · Ellsberg One Design
Ellsberg One Design · Accident: propeller failure/malfunction en route
From S07 · Bend Municipal, OR to an unrecorded destination
Event
- NTSB case
- SEA02LA003
- 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
- Unknown
- 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
Ellsberg One Design
- Aircraft type
- Ellsberg ONE DESIGN
- Category
- Airplane
- 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
- N55TE
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From S07 · Bend Municipal, ORTo not recorded
- Aircraft age
- Not recorded
- 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 · cruise
- First occurrenceThe 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
- Propeller failure/malfunction
- 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
- Propeller system/accessories, counterweight › Separation
- Propeller system/accessories, counterweight › Undertorqued
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
Just after the pilot entered the aerobatic box in his experimental One Design aircraft, the airplane developed an "extreme vibration." The pilot therefore shut the engine off and began a glide toward a nearby road. During the descent, with the propeller windmilling, the aircraft shook so violently that it was very difficult for the pilot to see, and he became concerned that the engine might separate from the airframe. When the aircraft reached the ground, the pilot tried to land on a narrow road, but with his visibility still significantly effected by the vibration of the airframe, he was unable to keep the One Design within the lateral confines of the road. During the landing roll, one of the main wheels departed the side of the road and encountered soft terrain. The main gear wheel then began to sink into the soft terrain, and the aircraft nosed over onto its back. It was later determined that one of the propeller counterweight mounting brackets (along with the counterweight itself) had separated from the propeller. A post-accident inspection of the counterweight on the apposing blade revealed that one of its mounting bolts was under-torqued approximately 115 inch-pounds below the value listed in the associated assembly torque table. The propeller, which was a non-certified model with composite blades, had been loaned to the pilot by the manufacturer, while his propeller was undergoing a periodic inspection.
Probable cause
the separation of a propeller counterweight mounting bracket due to incorrect mounting bolt torque. Factors include significant powerplant vibration during the forced landing, no suitable landing area, and soft terrain next to the narrow road on which the pilot attempted his emergency landing.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA02LA003
- Event ID
- 20011011X02079
- Case number
- SEA02LA003
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
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: local date, investigation status. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2001-10-06.
- API snapshot SHA-256: 866d0f61ab368954352ae6c33bef6f122bffe9847a99ccc300d20af77a807901; retrieved 2026-09-21T19:50:15.494Z.