Hard landing Accident Aerospatiale AS 350B Ecureuil N989WC,
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ASN Wikibase Occurrence # 157590
 
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Date:Monday 1 July 2013
Time:11:00
Type:Silhouette image of generic AS50 model; specific model in this crash may look slightly different    
Aerospatiale AS 350B Ecureuil
Owner/operator:Private
Registration: N989WC
MSN: 1923
Year of manufacture:1985
Total airframe hrs:10000 hours
Engine model:Turbomeca Arriel 1B
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Hamilton -   United States of America
Phase: En route
Nature:Private
Departure airport:Hamilton, MT (6S5)
Destination airport:Philipsburg, MT (U05)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
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.

Probable Cause: 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.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: WPR13LA302
Status: Investigation completed
Duration:
Download report: Final report

Sources:

NTSB

Location

Revision history:

Date/timeContributorUpdates
15-Jul-2013 06:28 Alpine Flight Added
21-Dec-2016 19:28 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
29-Nov-2017 08:50 ASN Update Bot Updated [Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative]

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