WPR21LA357 · Fonville SWEARINGEN SX300
Fonville SWEARINGEN SX300 · Accident: loss of engine power (total) en route
From Gila Bend Municipal Airport (E63) to Glendale Municipal Airport (GEU)
Narrative check · The NTSB narrative appears to contradict this record's injuries. Values are shown as recorded, not corrected; compare with the narrative.
Event
- NTSB case
- WPR21LA357
- 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
- Event fatalities
- Unknown
- 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
Fonville SWEARINGEN SX300
- Aircraft type
- Fonville SWEARINGEN SX300
- 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
- N5SX
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Gila Bend Municipal Airport (E63), Gila Bend, AZTo Glendale Municipal Airport (GEU), Glendale, AZ
- Aircraft age
- About 25 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
- Loss of engine power (total)
- 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 power plant
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot departed uneventfully, leveled the airplane at 1,000 ft above ground level, and set the engine power to 2,500 rpm. He then initiated a climb, during which the engine power increased to 3,200 rpm and the engine became “unresponsive to input” just before it lost power. The pilot initiated a forced landing, during which the pilot sustained minor injuries and the airplane sustained substantial damage. A postaccident examination of the engine revealed the left magneto flange was securely clamped at the mounting pad; however, the flange was detached from the magneto. The three screw holes where the flange and magneto should have attached exhibited severe elongation and deformation, which was indicative of a loss of torque and subsequent prolonged inability to maintain proper mating of the magneto flange and housing. The three attachment screws were not recovered. The condition observed during postaccident examination likely existed for an extended time as evidenced by fretting and wear signatures of the housing components. Internally, the magneto components become misaligned to such a degree that proper magneto internal timing and the ability to operate within the manufacturer’s specification were affected, resulting in the total loss of engine power.
Probable cause
The total loss of engine power due to the failure of the left magneto.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR21LA357
- Event ID
- 20210929103991
- Case number
- WPR21LA357
- 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, 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: f07fb40e2475c2e4280a11ee23cdf529214818ff937e03d919b49fd8f1284f7b; retrieved 2026-09-16T14:35:51.924Z.