Aerospatiale AS-350BA N26WW

Summary

On 28 October 2000 at about 21:37 local time, a Aerospatiale AS-350BA registered N26WW, operated by Tex-Air Helicopters Inc., was involved in an accident near E. Cameron 200, United States. One person was on board and one died. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

28 October 2000 at 21:37

Classification

Accident

Location

E. Cameron 200, United States

Nearest airport

Vermilion 200 (V200)

Coordinates

28.7381, -92.6300

Aircraft

Aerospatiale AS-350BA

Registration

N26WW

Category

Helicopter

Engines

1

Operator

Tex-Air Helicopters Inc.

Operating rule

Part 91: General Aviation

Purpose of flight

Positioning

Phase of flight

Not recorded

Route

E. Cameron 231A → Vermillion 200

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

FTW01FA017

1 person died.

the loss of engine power due to an internal engine oil leak that started an internal engine fire and the pilot's inadequate autorotation which resulted in a hard landing. A contributing factor to the accident was the rough water condition.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The helicopter departed from a helipad located on an offshore oil platform, and was 3 minutes from landing at a refueling helipad on another platform, when the pilot transmitted two distress calls indicating the helicopter was "going down." There were no witnesses to the accident; however, 9 minutes after the distress calls were heard, the helicopter was found floating inverted in 3-4 foot seas. Subsequently, the helicopter sank and was later recovered and examined. Examination of the helicopter revealed no anomalies with the airframe or flight control systems. Examination of the engine revealed that the first and second stage turbine blades were fractured due to extreme heating. One blade of the second stage tubine disk had liberated from its retention slot, and all the blade roots and retention slots of this disk exhibited permanent outboard deformation, due to a combination of centripetal forces from engine operation and excessive heat. In contrast, the blade roots and retention slots of the first stage turbine disk did not exhibit evidence of outboard deformation, most likely since they were located further away from the heat source. The rear bearing assembly (located aft of the second stage disk) was contaminated with coke. The coking suggests that oil was leaking from the engine and migrating from the rear bearing assembly. The aft side of the second stage turbine disk displayed dark stain marks in the form of streaks. A passage exists that would allow oil to flow from the rear bearing to the aft face of the second stage turbine disk. Oil that strikes the disk would flow into the hot stream of gases and auto-ignite, starting a fire. Oil migration can occur if the rear bearing scavenge and vent tubes become blocked; however, the scavenge and vent tubes were checked during the engine examination and were not found blocked.

Quoted verbatim from the NTSB record.