Pilot Debrief

MOSQUITO XE near Oshkosh, WI — 2014-08-01

Final reportCEN14LA401
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Date
2014-08-01
Location
Oshkosh, WI, USA
Airport
KOSH
Aircraft
MOSQUITO XE
Registration
CF-HEZ
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Takeoff roll

Probable cause

The failure of the retaining assembly on the tail rotor blade, which resulted in the separation of the blade and the subsequent loss of helicopter control.

NTSB narrative

Just after takeoff, the experimental, amateur-built helicopter started to rotate and then impacted the ground in a level attitude, which resulted in substantial damage to the helicopter. Examination revealed that one tail rotor blade had separated from the tail rotor and gearbox assembly and that the blade had separated cleanly from the assembly; neither the collar nor the pins used to secure the blade were located. The pilot reported that he had been testing this tail rotor design for 4 years. A tension/torsion strap and two steel pins were used to retain the blade. The strap was not completely restricted from movement, and, over time, movement and wear resulted in the failure of the retaining assembly. The tail rotor assembly was a unique design and was not used in any other application.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Inspecting the tail rotor assembly before the flight could have prevented failure.

NTSB coding

Evidence available

  • 2 docket documents
View NTSB final reportView NTSB docket

Docket documents2

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