Pilot Debrief

MD Helicopter Inc MD 900 near Amherst, TX — 2008-10-19

Final reportCEN09IA032
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Date
2008-10-19
Location
Amherst, TX, USA
Aircraft
MD Helicopter Inc MD 900
Registration
N902NM
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Cruise

Probable cause

The failure of the vertical stabilizer control adapter due to reverse bending fatigue.

NTSB narrative

While in cruise flight, the helicopter experienced a hard right yaw and subsequent pitching moment up and down. The pilot was able to regain control of the helicopter and land without further incident. Examination revealed that the left vertical stabilizer control system adapter had failed. Metallurgical examination revealed that the failure mode was reverse bending fatigue. The vertical stabilizer control system adapter has been replaced with an improved design. Further, the Federal Aviation Administration has issued an Airworthiness Directive (AD) requiring all MD900 helicopter operators with the old VSCS tube adapters to comply with airspeed and autopilot restrictions. If an operator replaces the old VSCS tube adapter with the new design, the AD is not applicable.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
MDHI issued service bulletins for VSCS tube adapter issues prior to the incident.

NTSB coding

  • Flight control sys malf/fail · Enroute-cruise

Evidence available

  • 5 docket documents
View NTSB final reportView NTSB docket

Docket documents5

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