FlarePath

What happened

NTSB summary, verbatim

The helicopter was en route back to the crew’s home airfield when it encountered a flock of geese during the night flight. The helicopter was in cruise flight about 500-600 ft above ground level and at 110 knots groundspeed when the encounter occurred. The bird strike resulted in an inflight breakup of the helicopter and subsequent impact with terrain. Examination of the helicopter did not reveal any preimpact anomalies that would have contributed to the accident. Bird strike signatures were located on the main rotor pitch change links, which were both fractured in overload. Loss of a main rotor pitch change link would result in the loss of main rotor blade pitch directional control, vibrations, and excessive blade flapping. DNA testing found that all remains were consistent with female cackling geese, which have an average mass of 4.2 pounds Preflight mission planning for the flight would likely not have detected a risk for a bird strike. A review of military and civilian bird hazard websites showed that at the time of the accident, the probability of bird strike in that area was deemed to be low. In addition, historic migration data also estimated the probability of a bird strike at the time of the accident as low.

Photographs

7the aircraft, and what the investigators found

Wreckage and site documentation · 7 photographs from the docket

Photographs are NTSB docket attachments — works of the US government, in the public domain. Captions are the Board’s own.

Probable cause

the Board's determination

The helicopter’s inflight collision with cackling geese, resulting in an inflight breakup.

Occurrence sequence

3 stepsNTSB coding · CICTT taxonomy

1 · Enroute-cruise
Birdstrike
defining event
2 · Enroute-cruise
Loss of control in flight
3 · Uncontrolled descent
Collision with terr/obj (non-CFIT)

Findings

1 causal · 1 contributing

CAUSE
Environmental issues › Physical environment › Object/animal/substance › Animal(s)/bird(s) — Effect on operation
FACTOR
Environmental issues › Conditions/weather/phenomena › Light condition › Dark — Effect on personnel

NTSB analysis

from the final report

The helicopter was en route back to the crew’s home airfield when it encountered a flock of geese during the night flight. The helicopter was in cruise flight about 500-600 ft above ground level and at 110 knots groundspeed when the encounter occurred. The bird strike resulted in an inflight breakup of the helicopter and subsequent impact with terrain. Examination of the helicopter did not reveal any preimpact anomalies that would have contributed to the accident. Bird strike signatures were located on the main rotor pitch change links, which were both fractured in overload. Loss of a main rotor pitch change link would result in the loss of main rotor blade pitch directional control, vibrations, and excessive blade flapping. DNA testing found that all remains were consistent with female cackling geese, which have an average mass of 4.2 pounds Preflight mission planning for the flight would likely not have detected a risk for a bird strike. A review of military and civilian bird hazard websites showed that at the time of the accident, the probability of bird strike in that area was deemed to be low. In addition, historic migration data also estimated the probability of a bird strike at the time of the accident as low.

BELL 206AIR EVAC EMS INC