Pilot Debrief

ROBINSON HELICOPTER COMPANY R44 II near Valdez, AK — 2015-12-16

Final reportANC16LA010
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Date
2015-12-16
Location
Valdez, AK, USA
Airport
VDZ
Aircraft
ROBINSON HELICOPTER COMPANY R44 II
Registration
N255VS
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Takeoff roll

Probable cause

The overhaul facility’s improper and excessive use of an approved lubricant during overhaul of the fuel injection servo, which resulted in a disruption of fuel flow and a total loss of engine power.

NTSB narrative

The commercial pilot was departing on a power line patrol flight in the helicopter. After liftoff, the pilot hovered the helicopter about 10 ft above ground level (agl) before commencing a left turn, accelerating to about 25 knots, and initiating a climb. As the helicopter climbed through about 20 ft agl, the engine experienced a total loss of power. The pilot performed an autorotation, but the helicopter landed hard, resulting in substantial damage to the fuselage, skids and tail boom. Review of the accident helicopter's maintenance records revealed that the fuel injection servo had been repaired and reinstalled about 2 hours before the accident flight. During postaccident examination of the fuel injection servo assembly, small amounts of a white, greasy substance were discovered in the servo assembly. The greasy substance, later identified as DuPont Krytox, is a lubricant used in small amounts and specific locations, during reassembly after overhaul or maintenance of the fuel injection servo assembly. Inspection of a fuel injection servo from a different helicopter that had been overhauled by the same maintenance facility revealed similar contamination. A representative from the maintenance facility stated that about 6 months before the accident, they had begun using Dupont Krytox, an approved lubricant, but did not realize that it was being used in excess and in locations not approved per the maintenance/service manual. Due to the improper and excessive use of assembly lubricant and the lack of engine anomalies, it is likely that the lubricant contaminated the fuel injection servo, causing a disruption in fuel flow, which resulted in a total loss of engine power.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Proper inspection of fuel injection servo before installation could have prevented failure.

NTSB coding

Evidence available

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

Docket documents8

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