CHI82FA304 · Hiller UH12L4
Nelsonind Hiller UH12L4 · Accident: airframe, component or system failure during initial climb
From Wisconsin Dells, WI to Wisconsin Dells, WI
Event
- NTSB case
- CHI82FA304
- 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
Hiller UH12L4
- Aircraft type
- Hiller UH12
- 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
- N3748Z
- Operator
- Nelsonind
- Onboard fatalities
- Unknown
- Route
- From Wisconsin Dells, WITo Wisconsin Dells, WI
- 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
- Initial climb
- 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
- Airframe, component or system 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
- Rotor drive system, clutch assembly › Failure, total
- Rotor drive system, clutch assembly › Worn
Approximate · Estimated position: the centre of Wisconsin Dells, WI, the place the record names. Not the accident site.
NTSB narrative
DURING CLIMB, AT ABOUT 200 FT AGL, THE M/R LOST RPM. DURING AUTOROTATION THE ENG RPM INCREASED BEYOND THE RED LINE WHEN THE PLT ADDED POWER. THE HELICOPTER MADE A HARD LANDING IN A RESIDENTIAL AREA. INSPECTION OF THE MERCURY CLUTCH REVEALED THAT THE EXTERIOR SURFACE OF THE CLUTCH DRUM EXHIBITED EVIDENCE OF EXCESSIVE OVERHEATING. THE INSIDE SURFACE OF THE DRUM SHOWED SEVERE GLAZING & DISCOLORATION IN THE CLUTCH SHOE WEAR AREA. THERE WERE ALSO SEVERAL CRACKS IN THE CLUTCH DRUM. THE HOUSING BEARING JOURNAL HAD EXPERIENCED SEVERE PITTING. THERE WAS ALSO SEVERE WEAR IN THE BEARING JOURNAL AREA. THE CLUTCH SHOES SHOWED SIGNIFICANT GLAZING & SURFACE CRACKING, & WERE SEVERELY WORN.
Verbatim NTSB analysis from the NTSB dataset
Sources
NTSB record CHI82FA304
- Event ID
- 20020917X03084
- Case number
- CHI82FA304
- 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: 23079ce0eb9e92049f706f6358edd9ec91bf42f896a734b818fbf1930d4ee724; retrieved 2026-09-21T18:09:20.102Z.