SEA99LA108 · Williamson/Williamson RV-4
Williamson/Williamson RV-4 · Accident: total loss of engine power (non-mechanical) en route
From Southwest Oregon Regional Airport (OTH) to an unrecorded destination
Event
- NTSB case
- SEA99LA108
- 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
Williamson/Williamson RV-4
- Aircraft type
- Williamson/williamson RV-4
- 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
- N6NW
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Southwest Oregon Regional Airport (OTH), North Bend, 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 · climb to 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
- Total loss of engine power (non-mechanical)
- 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
- Induction air ducting › Obstructed
- Miscellaneous eqpt/furnishings, engine inlet covers › Not removed
- Pilot in command › Aircraft preflight, inadequate
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot reported that after takeoff, at an altitude of approximately 600 feet above ground level (AGL), the engine suddenly stopped. Attempts to restart the engine were unsuccessful, and the pilot attempted a forced landing onto a road. As the aircraft approached the road at about 300 feet AGL, a car turned onto the road. It became apparent to the pilot that the aircraft would overtake and hit the car from the rear if he attempted to land on the road, and the pilot thus attempted to turn the airplane to go up a driveway off the road. The airplane subsequently struck fence posts during the forced landing. FAA inspectors who performed a post-accident examination of the aircraft's engine found a 2 1/2 inch diameter soft blue ball, wrapped in Scotch tape and with a flag of red plastic tape attached, lodged in the carburetor air inlet. The inspectors reported that the aircraft owner identified the ball as an improvised engine air inlet cover, which he had placed into the engine air inlet to prevent foreign objects from entering the inlet during ground storage of the aircraft. The FAA inspectors reported finding no other evidence of pre-impact engine mechanical malfunction.
Probable cause
Inadequate aircraft preflight inspection (engine air inlet cover not removed) by the pilot, resulting in obstruction of the carburetor air inlet in flight and consequent inflight engine stoppage. Factors contributing to the accident included a vehicle entering the attempted forced landing surface, and fence posts in the forced landing area.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA99LA108
- Event ID
- 20001212X19367
- Case number
- SEA99LA108
- 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: investigation status. 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: 6ea90f3702b9e9b3aaceca206dc365b7705501013c34e0e1bbd5d3341bf5face; retrieved 2026-09-21T10:57:04.637Z.