# NTSB FTW86LA119: Aerospatiale AS35OD, N229EH, Theriot, LA, June 16, 1986

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: June 16, 1986, 08:45 local (13:45 UTC)
- Place: Theriot, LA
- Coordinates: 29.360553, -90.700027 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=29.3606&lon=-90.7000&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 22047
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW86LA119
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/22047/pdf
- Page: https://openairdocs.org/ntsb/FTW86LA119

## 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
  - accessory drive assy,drive shaft - disintegrated (cause)
- Forced landing, descent - emergency
  - autorotation - performed, pilot in command (contributing factor)
- Hard landing, landing - flare/touchdown
  - terrain condition - high obstruction(s) (contributing factor)
  - rotor rpm - not maintained, pilot in command (contributing factor)
  - proper glidepath - not possible, pilot in command (contributing factor)

## Analysis

THE PILOT EXPERIENCED A SUDDEN YAW IN THE HELICOPTER AT CRUISE FLIGHT. THE NG STARTED WINDING DOWN CONFIRMING AN ENGINE FAILURE. THE PILOT HAD TO EXTEND AN AUTOROTATION OVER A TREE LINE, WHICH CAUSED THE RPM TO DECREASE, AND MADE A HARD LANDING IN AN ADJACENT FIELD. DAMAGE TO THE HELICOPTER INCLUDED THE TAIL SECTION, LANDING GEAR AND MAIN ROTOR. INSPECTION OF THE ENGINE REVEALED THAT BOTH THE GEAR SPUR COMPRESOR SHAFT AND THE GEAR SPUR ACCESSORY DRIVE WERE MISSING TEETH. THE INSPECTION ALSO REVEALED THAT METAL FRAGMENTS FROM THE GEARS WERE DISTRIBUTED THROUGHOUT THE ENGINE'S LUBRICATION SYSTEM.

## Aircraft

- Registration: N229EH (not matched to a registry record)
- Reported make and model: AEROSPATIALE AS35OD
- Category: Helicopter
- Serial number: 1227
- Airframe hours: 2278
- Engines: LYCOMING LTS101600A-2 531 lbs thrust turbo shaft
- Damage: Substantial damage
- Flight: Part 135
- Registered owner: Energy Helicopters
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, June 13, 1986, 11 hours before
- Departed: HUM, HOUMA, LA
- Flight plan: VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 42; commercial; airplane ratings: single-engine land; medical: class 1, valid medical--w/ waivers/lim; seat: right; flight hours: 7,893 total, 576 in this make and model, 7,833 as pilot in command, 77 in the last 90 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 7 statute miles
- Lowest ceiling: none
- Temperature: 81 °F, dew point 64 °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 19860616025309A](https://openairdocs.org/incident/19860616025309A), Jun 16, 1986: Snias AS350D, Theriot, LA, Substantial damage. Aircraft landed hard from autorotation after engine failed. Spur gear and drive were found broken.

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.