# NTSB CHI83FA428: Sikorsky S-76A, N521AC, Chicago, IL, September 14, 1983

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Field investigation · Final report
- Date: September 14, 1983, 18:23 local (23:23 UTC)
- Place: Chicago, IL
- Coordinates: 41.880138, -87.64096 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.8801&lon=-87.6410&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 3 minor, 3 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 12025
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI83FA428
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/12025/pdf
- Page: https://openairdocs.org/ntsb/CHI83FA428

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise - normal
  - rotorcraft flight control,tail rotor cable - chafed (cause)
  - maintenance,installation - improper, other maintenance personnel (cause)
  - rotorcraft flight control,tail rotor cable - failure,total (cause)
- Forced landing, landing
  - autorotation - performed, pilot in command
- Hard landing, landing - flare/touchdown
- Roll over, standing
  - landing gear,float assembly - overload

## Analysis

WHILE CRUISING AT 2000 FT MSL & 150 KTS, THE CREW HEARD A LOUD NOISE, AND SIMULTANEOUSLY, THE HELICOPTER YAWED APRX 30 TO 40 DEG TO THE RIGHT & PITCHED NOSE DOWN. THE AIRCREW BEGAN AN AUTOROTATION & ACTIVATED THE EMERGENCY FLOATS. THE HELICOPTER CONTINUED IN A RIGHT DESCENDING TURN DURING THE AUTOROTATION. TOUCHDOWN IN THE WATER (LAKE MICHIGAN) OCCURRED WITH A FORWARD SPEED OF ABOUT 40 TO 50 KTS. AFTER CONTACTING THE WATER, THE HELICOPTER TURNED AN ADDITIONAL 180 DEG, THEN LISTED ABOUT 10 DEG TO THE LEFT. THE OCCUPANTS DONNED THEIR LIFE VESTS & EXITED THE HELICOPTER. ABOUT 11 TO 13 MINUTES AFTER LANDING, THE ACFT ROLLED OVER IN THE WATER & EVENTUALLY SUNK. THE OCCUPANTS WERE RESCUED BEFORE THE HELICOPTER SANK. AN INVESTIGATION REVEALED THAT THE LEFT SIDE TAIL ROTOR CABLE. PN 76400-03191-043, HAD FAILED WHERE IT HAD BEEN RUBBING. THE RUBBING WAS ATTRIBUTED TO INCORRECT ROUTING OF THE CABLE.

## Aircraft

- Registration: [N521AC](https://openairdocs.org/deregistered/N521AC-1983-12-14), registration cancelled 1983-12-14, S/N 760159 (OpenAirDocs)
- Reported make and model: SIKORSKY S-76A
- Registry model: [Sikorsky S-76A](https://openairdocs.org/model/sikorsky-s-76a) (registry code 8143006) (OpenAirDocs)
- Category: Helicopter
- Serial number: 760159
- Airframe hours: 631
- Engines: ALLISON 250-C30 969 horsepower turbo shaft
- Damage: Destroyed
- Flight: Executive/Corporate, Part 91
- Registered owner: Amway Corp.
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, September 13, 1983, 1 hours before
- Departed: CGX, CHICAGO, IL
- Destination: GRR, GRAND RAPIDS, MI

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 29; flight instructor, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: helicopter, airplane; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 3,730 total, 220 in this make and model, 3,296 as pilot in command

## Weather

- Conditions: Visual (VMC), Day
- Wind: 360° at 10 knots
- Visibility: 20 statute miles
- Lowest ceiling: none
- Temperature: 68 °F, dew point -0 °F
- Altimeter: 30.00 inHg

## 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 19830914048899A](https://openairdocs.org/incident/19830914048899A), Sep 14, 1983: Skrsky S76A, Chicago, IL, Destroyed. Tail rotor cable routed over instead of under keeper, chafed, broke. Partial yaw control, ditched.

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.

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