# NTSB NYC92GA147: Sikorsky S-76A, N50KY, Graefenburg, KY, August 7, 1992

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Final report
- Date: August 7, 1992, 11:10 local (15:10 UTC)
- Place: Graefenburg, KY
- Coordinates: 38.190685, -84.859603 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=38.1907&lon=-84.8596&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 5 serious, 1 minor
- Status: Completed, report September 20, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 37077
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=NYC92GA147
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/37077/pdf
- Page: https://openairdocs.org/ntsb/NYC92GA147

## Probable cause

AN INADEQUATE PREFLIGHT INSPECTION BY THE FLIGHT CREW BY FAILING TO ASSURE THAT ALL FOUR OF THE ENGINE COWLING LATCHES WERE PROPERLY SECURED, WHICH RESULTED IN SUBSEQUENT FAILURE OF SECTION II OF THE TAIL ROTOR DRIVESHAFT AFTER THE COWLING CONTACTED THE MAIN ROTOR BLADES AND TAIL ROTOR DRIVESHAFT.

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise
  - aircraft preflight - inadequate (cause)
  - engine compartment - not secured (cause)
  - rotor drive system,tail rotor drive shaft - failure,total (cause)
  - rotor system,tail rotor blade - separation
- Forced landing, descent - emergency
  - autorotation - performed, pilot in command
- In flight collision with object, landing
  - terrain condition - mountainous/hilly
  - object - tree(s)

## Analysis

BEFORE FLT, THE COPLT BGN A PREFLT INSPN, & SUBSEQUENTLY, THE HELICOPTER WAS MVD FM THE HANGAR TO THE TERMINAL, WHERE A WITNESS OBSERVED THE ENG COWLING OPEN. THE PLT ALSO MADE A WALKAROUND VISUAL INSPN OF THE HELICOPTER BFR FLT. NEITHER OF THE FLTCREW NOTED ANY DISCREPANCY. ABT 1 MIN & 40 SEC AFTER TAKEOFF, THE FLT CREW HEARD A NOISE, FLWD BY LOSS OF DRCTNL CTL; 3 OF THE PSGRS NOTED THE ODOR OF SOMETHING OVERHEATING. AN AUTOROTATION & LANDING WERE MADE ON HILLY TRRN, WHERE THE HELICOPTER CAME TO REST IN A RAVINE AGAINST A TREE. DRG AN EXAM, THE 2 LEFT SIDE ENG COWLING LATCHES WERE FND OPEN; ALSO, THE LEFT SIDE OF THE AFT ENG COWLING WAS OPEN. THERE WAS EVIDENCE THAT DURING FLT, THE LEFT SIDE OF THE COWLING CONTACTED THE MAIN ROTOR BLADES; THE COWLING THEN MADE CONTACT WITH SECTION II OF THE TAIL ROTOR DRIVESHAFT. FRICTION BTN THE COWLING & THE DRIVESHAFT RESULTED IN LOCALIZED HIGH TEMPERATURE & THE TAIL ROTOR SHAFT FAILED AT THAT LOCATION. ONE OF THE 4 TAIL ROTOR BLADES SEPARATED DURING THE OCCURRENCE.

## Aircraft

- Registration: [N50KY](https://openairdocs.org/deregistered/N50KY-1995-02-07), registration cancelled 1995-02-07, S/N 760059 (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: 760059
- Airframe hours: 3950
- Engines: ALLISON 250-C30 650 horsepower turbo shaft
- Damage: Destroyed
- Flight: Public aircraft, Part 91
- Registered owner: Commonwealth Of Kentuky
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, May 29, 1992, 46 hours before
- Departed: FFT, FRANKFORT, KY
- Destination: FTK, FT KNOX, KY
- Flight plan: Company VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 45; commercial; instrument ratings: helicopter; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 6,070 total, 680 in this make and model, 5,800 as pilot in command, 125 in the last 90 days, 42 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 140° at 7 knots
- Visibility: 4 statute miles
- Lowest ceiling: none
- Temperature: 72 °F, dew point 66 °F
- Altimeter: 30.00 inHg
- Observed at: LEX, 20 nm away

## 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 19920807056889A](https://openairdocs.org/incident/19920807056889A), Aug 7, 1992: Skrsky S76A, Frankfort, KY, Destroyed. Indicates unsecured right engine cowl lifted inflight. Hit main rotors debris hit tail rotors. Lost tail rotor use.

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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