ERA21LA159 · Cessna 210 N
Cessna 210 N · Accident: electrical system malfunction/failure en route
From Savannah Hilton Head International Airport (SAV) to an unrecorded destination
Event
- NTSB case
- ERA21LA159
- 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
Cessna 210 N
- Aircraft type
- Cessna 210
- 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
- N7736K
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Savannah Hilton Head International Airport (SAV), Savannah, GATo not recorded
- Aircraft age
- About 42 years (built 1979)
- 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
- Electrical system malfunction/failure
- 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 systems
- Personnel issues › Action/decision
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 was diverting to an airport to refuel when the airplane’s turbine inlet temperature (TIT) warning light illuminated. Shortly after, the autopilot “fail” light came on and the autopilot disengaged, followed by other electrical components losing power or ability to operate. The pilot said that he was able to extend the landing gear, but the light that confirmed that the gear was down and locked was not working. He said that the gear sounded and appeared to be fully extended, so he chose not to use the emergency gear extension handle to make sure the gear was fully extended. On the subsequent landing rollout, both main landing gear collapsed, resulting in substantial damage to the left horizontal stabilizer. Postaccident examination of the airplane revealed that the housing plug for the alternator control unit (ACU) was loosely fitted and not properly mated. It is likely the housing plug came loose during turbulence, and the battery drained to a point that it could not provide adequate electricity to fully extend and lock the landing gear. The pilot reported no previous issues with the electrical system and no maintenance had been done to the ACU after a recent annual inspection.
Probable cause
The failure of the alternator control unit housing plug connection, which resulted in insufficient battery power to fully extend the landing gear. Contributing to the accident was the pilot’s decision to not use the emergency gear extension handle to secure the gear prior to landing.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ERA21LA159
- Event ID
- 20210321102790
- Case number
- ERA21LA159
- 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: 22eb826e7f8fd61c8c5492e29050b7db5f470a5f82512cfe4d01b18548266f03; retrieved 2026-09-16T13:51:32.357Z.