S N I A S AS-350B ECUREUIL N989WC

Summary

On 1 July 2013 at about 17:00 local time, a S N I A S AS-350B ECUREUIL registered N989WC was involved in an accident near Hamilton, Montana, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

1 July 2013 at 17:00

Classification

Accident

Location

Hamilton, Montana, United States

Nearest airport

Hamilton (6S5)

Coordinates

46.2483, -113.8608

Aircraft

S N I A S AS-350B ECUREUIL

Registration

N989WC

Category

Helicopter

Year built

1985

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Hamilton → Philipsburg

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR13LA302

Nobody was injured.

The loss of engine power during cruise flight due to the fatigue failure of a pneumatic fuel controller pipe. Also causal was maintenance personnel’s failure to adequately maintain the pipe and replace it with a thicker type.

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

Read the full NTSB narrative

The pilot reported that, about 20 minutes after departure, the helicopter lost all engine power during cruise flight. The pilot performed an autorotation into a small forest clearing. During the landing sequence, the helicopter sustained substantial damage. Examination of the engine revealed that the pneumatic fuel controller (P2) pipe that delivered air pressure from the centrifugal compressor to the fuel control unit (FCU) had separated at the FCU fitting. The P2 pipe's failure allowed ambient air pressure to enter the line and resulted in the FCU commanding the engine to spool down to ground idle speed. The pipe exhibited deformation due to bending damage and signatures indicating that it was making contact with its union fitting at the FCU. The P2 pipe was a thin-walled type, which the engine manufacturer had recommended be replaced with a thicker version 29 years previously. Further, the engine manufacturer had issued multiple service letters advising maintenance personnel of the correct procedures for fitting, inspecting, and maintaining such air lines. The pipe's fracture surfaces at the separation point exhibited signatures consistent with fatigue as a result of noncompliance with the manufacturer's recommendations.

Quoted verbatim from the NTSB record.