Eurocopter France EC120B N266SD

Summary

On 14 July 2005 at about 02:10 local time, a Eurocopter France EC120B registered N266SD was involved in an accident near Fair Oaks, California, United States. 3 people were on board and 2 died, one was seriously injured. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

14 July 2005 at 02:10

Classification

Accident

Location

Fair Oaks, California, United States

Coordinates

38.6392, -121.2206

Aircraft

Eurocopter France EC120B

Registration

N266SD

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Public Use

Phase of flight

Not recorded

Route

Mather → Unknown

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

LAX05GA231

2 people died.

The failure of the constant delta P diaphragm in the fuel control unit, which resulted in an increased fuel flow and subsequent catastrophic failure of the engine. The diaphragm's failure was the result of improper installation by the engine manufacturer. A factor in the accident was the unsuitable nature of the terrain for a successful autorotation.

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

Read the full NTSB narrative

The engine experienced an overspeed and catastrophic failure on a law enforcement patrol flight and the helicopter collided with hilly terrain during a subsequent autorotation attempt. Witnesses reported the helicopter began emitting smoke and subsequently descended, impacting terrain near the bottom of a 60-degree sloped hillside. The terrain around the accident site was either steeply sloped hillside with mature trees or bordered by power lines. A post accident examination of the engine and components revealed the constant delta P diaphragm (located in the fuel control unit) had ruptured, resulting in a high and uncontrolled increase of fuel flow to the engine. The power turbine exhibited evidence of a substantial overspeed. All of the turbine blades were separated at their respective shear points. The gas generator turbine exhibited evidence of extreme thermal erosion; the blades were eroded to about 50 percent of their normal height. The centrifugal compressor exhibited evidence of extreme rubbing. A detailed examination of the diaphragm revealed that it had been installed incorrectly (inside-out). The maintenance and engine manufacturer's build records revealed that the diaphragm was last replaced at the engine manufacturer's facilities in France. Recovered Vehicle and Engine Multifunctional Display (VEMD) information supported the evidence of an engine and main rotor revolutions per minute (rpm) exceedance.

Quoted verbatim from the NTSB record.