# NTSB FTW84FA216: Sikorsky S-76A, N763AL, High Isl Blk595, May 1, 1984

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Field investigation · Final report
- Date: May 1, 1984, 14:00 local (19:00 UTC)
- Place: High Isl Blk595
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed
- Report: Approved by Office Director
- Safety recommendations: Yes
- NTSB case key (mKey): 21117
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW84FA216
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/21117/pdf
- Page: https://openairdocs.org/ntsb/FTW84FA216

## Sequence of events

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

- Loss of engine power(total) - mech failure/malf, cruise - normal
  - turbine assembly,shaft - fatigue (cause)
  - turbine assembly,turbine wheel - overspeed
  - turbine assembly,turbine wheel - burst
- Airframe/component/system failure/malfunction, cruise
  - electrical system - disabled (contributing factor)
  - fuel system - fire (contributing factor)
  - rotor drive system,tail rotor drive shaft - separation (contributing factor)
- Forced landing, descent - emergency
  - fuselage,crew compartment - smoke
- Roll over, landing - flare/touchdown
  - terrain condition - water,rough
  - autorotation - performed, pilot in command
  - misc rotorcraft,emergency floatation gear - disabled (contributing factor)

## Analysis

DURING CRUISE FLIGHT AT 500 FT OVER GULF WATERS, THE LEFT ENGINE SUSTAINED A MASSIVE, UNCONTAINED, EXPLOSIVE FAILURE. SHARPNEL PENETRATED THE RIGHT ENGINE, WHICH FAILED FROM DAMAGE. SHARPNEL ALSO PENETRATED THE AC AND DC JUNCTION BOXES, CAUSING COMPLETE ELECTRICAL FAILURE (NO MAYDAY CALL POSSIBLE). SHARPNEL FURTHER SEVERED THE TAIL ROTOR DRIVE SHAFT AND PENETRATED THE ACFT FUEL SYSTEM; FIRE BROKE OUT IN THE TRANSMISSION AREA AND THE COCKPIT FILLED WITH SMOKE. USING THE CO-PLT'S SIDE WINDOW FOR VISUAL ACQUISITION OF THE WATER SURFACE, A SUCCESSFUL AUTOROTATION WAS PERFORMED. HOWEVER, THE ACFT ROLLED OVER AND SANK SINCE THE EMERGENCY FLOATATION GEAR IS ELECTRICALLY OPERATED AND FAILED TO DEPLOY. AFTER SUCCESSFUL EVACUATION BY ALL OCCUPANTS, PLT RETURNED TO THE INVERTED ACFT AND DEPLOYED LIFE RAFTS. INVESTIGATION REVEALED LEFT ENGINE COMPRESSOR-TO-TURBINE COUPLING HAD FAILED IN FATIGUE. TURBINE WENT OVERSPEED AND BURST UNDER CENTRIFUGAL LOADS.

## Aircraft

- Registration: [N763AL](https://openairdocs.org/deregistered/N763AL-1988-08-11), registration cancelled 1988-08-11, S/N 760019 (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: 760019
- Airframe hours: 3589
- Engines: ALLISON 250-C30S 250 horsepower turbo shaft
- Damage: Substantial damage
- Fire: On-Ground
- Flight: Part 135
- Registered owner: Air Logistic Inc.
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, March 26, 1984, 80 hours before
- Departed: HI ISL BLK 595, GM
- Destination: FREEPORT, TX
- Flight plan: Company VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 37; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane, helicopter; medical: class 1, valid medical--w/ waivers/lim; seat: right; flight hours: 5,092 total, 348 in this make and model, 3,839 as pilot in command, 53 in the last 90 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 11° at 6 knots
- Visibility: 5 statute miles
- Lowest ceiling: none
- Temperature: 73 °F, dew point 70 °F
- Altimeter: 29.00 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 19840501024669A](https://openairdocs.org/incident/19840501024669A), May 1, 1984: Skrsky S76A, Freeport, LA, Substantial damage. Turbine to compressor coupling failure, nr 1 engine turbine separated, hit nr 2 engine and ac DC junction boxes.

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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