Pilot Debrief

EUROCOPTER AS 350 B3 near Troutdale, OR — 2011-07-27

Final reportWPR11LA352
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Date
2011-07-27
Location
Troutdale, OR, USA
Airport
TTD
Aircraft
EUROCOPTER AS 350 B3
Registration
N808LF
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Cruise

Probable cause

The in-flight separation of the tail rotor drive shaft cover as a result of maintenance personnel not ensuring that it was secured after a maintenance inspection; also causal was the pilot’s inadequate preflight inspection of the helicopter.

NTSB narrative

The pilot reported that, about 12 minutes into a repositioning flight following a maintenance task performed by a company mechanic, he felt something that he described as similar to a bird strike. The pilot subsequently elected to make a precautionary landing in order to assess the situation. During an examination of the helicopter after the uneventful landing, the pilot discovered that a portion of the tail rotor drive shaft cover was missing and that one main rotor blade and two tail rotor blades had been damaged. Postaccident discussions with the company’s director of maintenance determined that the maintenance staff (who had recently performed a maintenance inspection) and the pilot likely looked at the tail rotor drive shaft cover prior to the accident flight and presumed that it was secure or had been secured by someone else; however, it was not secure and came off during flight. Following the accident, the company implemented a primary mechanic position into its Field Mechanic Procedures in order to mitigate a similar occurrence.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Failure to properly secure the tail rotor drive shaft cowling before flight.

NTSB coding

Evidence available

  • 3 docket documents
View NTSB final reportView NTSB docket

Docket documents3

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