CEN21LA431 · Eurocopter AS350 B2
County of Oakland Eurocopter AS350 B2 · Accident: hard landing during autorotation
From Dupont-Lapeer Airport (D95) to an unrecorded destination
Event
- NTSB case
- CEN21LA431
- 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
Eurocopter AS350 B2
- Aircraft type
- Eurocopter AS350
- Category
- Helicopter
- 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
- N632SD
- Operator
- County of Oakland
- Onboard fatalities
- Unknown
- Route
- From Dupont-Lapeer Airport (D95), Lapeer, MITo not recorded
- Aircraft age
- About 19 years (built 2002)
- 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
- Autorotation
- 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
- Hard landing
- 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
- Personnel issues › Task performance
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The flight instructor reported that he intended to demonstrate to the student pilot a 180° autorotation with a power recovery near the ground. He planned to transition the helicopter into to a hover about 5 to 10 ft above ground level at the end of the maneuver. The instructor initially set the engine fuel control to the idle detent to simulate an engine failure and then entered an autorotation. As the autorotation progressed, the flight instructor repositioned the engine fuel control, but he failed to ensure that it had been placed into the flight detent. Without sufficient engine power at the end of the maneuver, the helicopter continued to descend with a low rotor speed, landed hard, and slid to a stop on the runway. Then the helicopter violently rocked side to side before the main rotor stopped rotating. During the accident sequence, the helicopter sustained substantial damage to a main rotor Starflex arm and the tail rotor driveshaft. Both the flight instructor and his student reported there were no mechanical malfunctions or failures of the helicopter that would have precluded normal operation.
Probable cause
The flight instructor’s failure to reposition the fuel control to the flight detent during a practice autorotation, which resulted in insufficient engine power to arrest the helicopter’s decent and a hard landing.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN21LA431
- Event ID
- 20210920103911
- Case number
- CEN21LA431
- 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: d4891dc61db3987736de919d79443268e73d69d6dc291b9d094df652b101c086; retrieved 2026-09-16T14:33:18.537Z.