Pilot Debrief

EUROCOPTER EC 130 B4 near Boulder City, NV — 2014-01-01

Final reportWPR14LA084
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Date
2014-01-01
Location
Boulder City, NV, USA
Airport
BVU
Aircraft
EUROCOPTER EC 130 B4
Registration
N133GC
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Approach

Probable cause

A loss of engine power due to fuel starvation as a result of the noncertificated maintenance technician’s failure to properly tighten and safety wire a B-nut fitting. Contributing to the accident was the maintenance technician’s failure to follow the manufacturer’s maintenance manual instructions.

NTSB narrative

The pilot stated that, during a postmaintenance operational check flight and while on final approach for landing, the fuel pressure indicator light illuminated, and the engine "flamed out." The pilot lowered the collective to initiate an autorotation; however, due to the low altitude and airspeed, the helicopter subsequently landed hard and rolled over. During a postaccident examination of the wreckage, a main fuel supply line B-nut fitting was found without the safety wire, and the nut was loose when turned by hand. Before the accident flight, the line had been disconnected during a task to replace the bidirectional suspension cross-bar assembly, and the accident flight was the first flight since the task was performed. According to the noncertificated maintenance technician who performed the task, the line was removed to defuel the fuel tank, which was contrary to manufacturer's maintenance manual instructions. Based on the evidence, it is likely that the B-nut fitting was not properly tightened and safety-wired during reassembly, which allowed it to back off due to normal engine vibration and resulted in the interruption of the fuel flow during flight.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Proper maintenance procedures not followed during fuel system work prior to flight.

NTSB coding

Evidence available

  • Photos
  • 11 docket documents
View NTSB final reportView NTSB docket

Docket documents11

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