Pilot Debrief

Gray Jim Robert Exec 90 near Caldwell, ID — 2016-10-19

Final reportWPR17LA009
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Date
2016-10-19
Location
Caldwell, ID, USA
Airport
EUL
Aircraft
Gray Jim Robert Exec 90
Registration
N716JB
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Initial climb

Probable cause

The pilot's failure to properly tighten the tension bolts during the installation of the alternator belt, which resulted in inadequate voltage to sustain ignition and the subsequent partial loss of engine power.

NTSB narrative

Shortly after takeoff for the personal flight, about 15 to 20 ft above ground level, the experimental amateur-built helicopter suddenly yawed right, followed by a partial loss of engine power. The private pilot then performed a partial nose-up, collective-down maneuver, but due to the low altitude and not being able to maintain sufficient rotor rpm, he chose to land in soft dirt off the side of the runway; the helicopter landed hard. The pilot had recently changed the alternator belt. A postaccident examination of the helicopter revealed that, during the maintenance, the pilot failed to properly tighten the tension bolts, which resulted in inadequate voltage to sustain ignition and the subsequent partial loss of engine power.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have ensured proper alternator belt tension before flight.

NTSB coding

Evidence available

  • 2 docket documents
View NTSB final reportView NTSB docket

Docket documents2

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