In-flight breakup of VH-ZMF following birdstrike

Casualties unknown • near Maroota, New South Wales

An investigation into the mid-air disintegration of a helicopter near Richmond airspace has identified a birdstrike and abrupt pilot inputs as key factors.

What happened

While cruising at approximately 700 ft AMSL, the VH-ZMF was traveling toward St Albans when it encountered a wedge-tailed eagle. The impact occurred just below the left windscreen of the helicopter. At the time of the encounter, the aircraft was approaching the Richmond airspace control boundary, a phase of flight that required the pilot to transition their attention from external scanning to internal cockpit tasks to perform a radio frequency change. This period of increased workload, coupled with intense sun glare from a position nearly directly overhead, likely hindered the pilot's ability to detect the bird before the collision.

Following the strike, the aircraft entered a pronounced climb and a right roll before pitching forward. This maneuver involved abrupt cyclic inputs and low to negative g rotor loading, which are known limitations for the two-bladed teetering rotor head system used in this aircraft type.

The investigation

Investigators analyzed biological samples found on the aircraft and near the crash site, which confirmed contact with a wedge-tailed eagle. Footage from first responders showed significant biological matter on the front left nose cowl of VH-ZMF. While the initial impact of the bird was not deemed heavy enough to cause structural failure on its own, the subsequent flight path was critical.

Examination of the tail boom and rotor blade tips revealed that the main rotor blades struck the tail boom, severing it. This contact caused the main rotor system and transmission to fail due to the extreme rotational forces generated by an unbalanced and compromised assembly. Witnesses at the scene reported seeing the blades strike the tail boom and described the resulting breakup as uncontrolled.

Findings

  • The pilot's visual effectiveness was likely reduced by sun glare and the necessity of managing radio frequency changes.
  • The birdstrike served as a catalyst that, when combined with sudden control movements, led to the structural failure.
  • The main rotor blades struck the tail boom, causing the in-flight disintegration of the aircraft.

Probable cause

The in-flight breakup was caused by the main rotor blades striking the tail boom following an abrupt control input, which was likely triggered by the pilot being startled by a wedge-tailed eagle strike during a period of high workload and sun glare.

Frequently asked questions

What happened in the 2022-07-09 Bell Helicopter Co 206L-1 accident near near Maroota, New South Wales?

An investigation into the mid-air disintegration of a helicopter near Richmond airspace has identified a birdstrike and abrupt pilot inputs as key factors.

What aircraft was involved and where did it happen?

The accident on 2022-07-09 involved a Bell Helicopter Co 206L-1, registration VH-ZMF, at near Maroota, New South Wales.

What was the probable cause of the accident?

The in-flight breakup was caused by the main rotor blades striking the tail boom following an abrupt control input, which was likely triggered by the pilot being startled by a wedge-tailed eagle strike during a period of high workload and sun glare.

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