ERA21LA091 · Cessna 172 C
Cessna 172 C · Accident: loss of engine power (total) on approach
Event
- NTSB case
- ERA21LA091
- 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
Cessna 172 C
- Aircraft type
- Cessna 172
- 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
- N8311X
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From not recordedTo not recorded
- Aircraft age
- About 59 years (built 1961)
- 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
- Approach · VFR pattern final
- 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
- 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 student pilot was practicing takeoffs and landings when the engine sputtered and lost all power while on final approach. The student pilot tried to restart the engine to no avail and subsequently made a forced landing in a wooded area. The airplane came to rest inverted in swampy terrain amongst trees. The magnetos were removed from the engine during the postaccident examination, and they failed to produce sparks when tested. Further examination of the magnetos revealed extensive corrosion present on the coil laminations between the coil and magnet. It is likely the rotor was unable to transmit electricity to the coil and therefore the magneto was unable to produce a spark. The magneto manufacturer maintenance manual and overhaul manual states the magneto time in service allowance is the time before overhaul for the engine or 12 years. The magnetos had not been overhauled and were 14 and 23 years old. No other engine anomalies were identified that would have prevented normal operation.
Probable cause
A total loss of engine power due to failure of the magnetos, which were not overhauled in accordance with the manufacturer’s time specifications.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ERA21LA091
- Event ID
- 20201229102466
- Case number
- ERA21LA091
- 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: e9fe627afaa70bfef59ebc8a9e035586f31f871a2d878a45fab2c5c8adac4769; retrieved 2026-09-16T13:31:45.725Z.