Accident Eurocopter AS 350B2 Ecureuil N5204X,
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ASN Wikibase Occurrence # 198733
 
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Date:Monday 27 October 2014
Time:16:04
Type:Silhouette image of generic AS50 model; specific model in this crash may look slightly different    
Eurocopter AS 350B2 Ecureuil
Owner/operator:U.S. Department of Homeland Security
Registration: N5204X
MSN: 3099
Year of manufacture:1998
Total airframe hrs:5781 hours
Engine model:Turbomeca Arriel 1D1
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Bisbee, AZ -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Unknown
Departure airport:Fort Huachuca/Sierra Vista Municipal Airport, AZ (FHU/KFHU)
Destination airport:Fort Huachuca/Sierra Vista Municipal Airport, AZ (FHU/KFHU)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The commercial pilot was maneuvering the turbine engine-equipped helicopter about 25 ft above ground level when the engine suddenly experienced a total loss of power. The pilot performed an autorotation, and the helicopter touched down hard and rolled over, coming to rest inverted. Examination of the engine revealed that the pneumatic control pipe (P2), which delivers air pressure from the centrifugal compressor on the engine to the fuel control unit (FCU), was disconnected at the engine fitting. The loss of P2 pressure to the FCU resulted in the FCU commanding the engine to spool down to ground idle speed by limiting the fuel flow. There was no evidence of malfunctions or anomalies on the pipe, threads, and union fastener. There was no evidence of torque stripe residue on the disconnected fitting, consistent with the likely scenario that, during past maintenance, the B-nut was not properly torqued and gradually vibrated off its attach fitting while in flight.
The engine manufacturer had several caution notifications within multiple maintenance task documents to prevent removal of the P2 pipe during washing and the risk of an engine failure due to insufficient torque.


Probable Cause: Failure of maintenance personnel to ensure adequate torque of a pneumatic control pipe (P2) fitting, which resulted in a loss of engine power during low altitude flight maneuvers.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: WPR15TA027
Status: Investigation completed
Duration:
Download report: Final report

Sources:

NTSB

Location

Revision history:

Date/timeContributorUpdates
19-Aug-2017 14:55 ASN Update Bot Added
01-Jun-2023 11:19 Ron Averes Updated

Corrections or additions? ... Edit this accident description

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