Pilot Debrief

ROBINSON HELICOPTER COMPANY R22 MARINER near Redding, CT — 2011-05-29

Final reportERA11IA320
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Date
2011-05-29
Location
Redding, CT, USA
Aircraft
ROBINSON HELICOPTER COMPANY R22 MARINER
Registration
N8313E
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Cruise

Probable cause

The pilot's inadequate helicopter preflight inspection and the mechanic’s inadequate annual inspection, both of which failed to detect a worn bolt in the tail rotor teeter hinge prior to its fracture due to fatigue.

NTSB narrative

The pilot stated that he felt an abnormal vibration in the helicopter during cruise flight. He performed a precautionary landing to residential driveway. Postincident examination revealed that the tail rotor teeter hinge bolt had fractured completely due to fatigue and that there was no torque stripe on the bolt to help identify possible movement. The manufacturer’s preflight inspection checklist required the pilot to verify that the tail rotor teeter hinge bolt does not rotate. When asked about preflight inspections, the pilot stated that he does not always use the manufacturer's preflight checklist. Maintenance records show that the most recent annual inspection was performed about 4 weeks before the incident. According to the manufacturer's maintenance procedures, during an annual inspection, a mechanic should verify that the tail rotor teeter hinge bolt remains stationary when teetering the hub. Also, it is recommended that a mechanic applies a torque stripe to the bolt. In addition, the maintenance manual contained an unboxed warning message about the importance of the correct installation of the tail rotor to prevent a failure of the teeter hinge bolt and loss of the tail rotor.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot should have ensured proper installation of the tail rotor teeter hinge bolt.

NTSB coding

  • Sys/Comp malf/fail (non-power) · Enroute
  • Maintenance
  • Preflight Inspection

Evidence available

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

Docket documents12

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