# NTSB CHI82FA304: Hiller UH12L4, N3748Z, Wisconsin Dells, WI, August 12, 1982

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Field investigation · Final report
- Date: August 12, 1982, 14:40 local (19:40 UTC)
- Place: Wisconsin Dells, WI
- Location: 43.6384° N, 89.7758° W: Placed by OpenAirDocs: center of Wisconsin Dells, WI, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=43.6384&lon=-89.7758&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious, 1 minor, 1 uninjured
- Status: Completed, report August 12, 1983
- Report: Approved by Office Director
- NTSB case key (mKey): 73081
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI82FA304
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/73081/pdf
- Page: https://openairdocs.org/ntsb/CHI82FA304

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, takeoff - initial climb
  - vertical takeoff - performed, pilot in command
  - rotor drive system,clutch assembly - worn (cause)
  - rotor drive system,clutch assembly - failure,total (cause)
- Forced landing, landing - flare/touchdown
  - autorotation - performed, pilot in command

## Analysis

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.

## Aircraft

- Registration: [N3748Z](https://openairdocs.org/deregistered/N3748Z-1990-08-20), registration cancelled 1990-08-20, S/N 2545 (OpenAirDocs)
- Reported make and model: HILLER UH12L4
- Registry model: [Hiller UH-12L4](https://openairdocs.org/model/hiller-uh-12l4) (registry code 4360128) (OpenAirDocs)
- Category: Helicopter
- Serial number: 2545
- Airframe hours: 1513
- Engines: LYCOMING VO-540-2CA 250 horsepower reciprocating
- Damage: Substantial damage
- Flight: Part 91
- Operator: Nelsonind, Inc.
- Registered owner: Nelsonind, Inc.
- Departed: WISCONSIN DELLS, WI
- Destination: WISCONSIN DELLS, WI

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 25; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; flight hours: 431 total, 354 in this make and model, 354 as pilot in command, 139 in the last 90 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 25 statute miles

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19820812038149A](https://openairdocs.org/incident/19820812038149A), Aug 12, 1982: Hiller UH12L4, Wisconson Dells, WI, Substantial damage. Needles split during a sightseeing flight. Made hard autorotation landing. Main rotor drive clutch worn out.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.