ZK-HOJ Credit: Airwork (NZ) Ltd
ZK-HOJ Credit: Airwork (NZ) Ltd
MD Helicopters 500D, ZK-HOJ, In-flight breakup, Near Wānaka Aerodrome, 18 October 2018
Occurrence Date
Report Publication Date
What happened
At 1053 on 18 October 2018, an MD Helicopters MD 500D helicopter registered ZK-HOJ (the helicopter) took off from Wānaka Aerodrome with a pilot and two Department of Conservation workers on board. The flight was part of a Department of Conservation operation to control the wildlife population in national parks.

The helicopter had just departed from the perimeter of the aerodrome when it started to break up in flight, began spinning while descending near vertically and caught fire after it struck the ground.

None of the three occupants on board survived the accident.

Why it happened
The Transport Accident Investigation Commission (the Commission) found that it was very likely that the left-rear door opened unexpectedly in flight and a pair of unsecured overalls exited from the rear cabin and was struck by the tail rotor. That led to the tail rotor assembly breaking off from the tail boom and being propelled forward, then being struck by two of the five main rotor blades. That caused the outer sections of those two adjacent main rotor blades to break off. The tail boom was then struck by a main rotor blade and subsequently failed, resulting in the tail section separating and the helicopter becoming uncontrollable.

The Commission found it very likely that the left-rear door opened as a result of observed wear in the left-rear door-latch mechanism and the non-specific door-latch maintenance requirements, and that this door opening initiated the accident sequence. Given the operator’s practice of not using restraints to secure cargo within the cabin of this helicopter, and that items were distributed across the main wreckage site, it is virtually certain that the cargo items had not been properly secured with a seat belt or other restraining device.

In the absence of clear requirements to report door-opening events, or an understanding that these events could have adverse consequences, it is likely that the risks associated with them either may not be recognised or will become normalised. This could be detrimental to safety.

The Commission also found that ambiguity in the Civil Aviation Rules in the definition of crew and passengers continues to be a source of confusion for pilots and operators.

What we can learn
A helicopter door opening in flight presents a significant risk to the helicopter and its occupants. It is important that pilots report all incidents of doors opening unexpectedly in flight.

Unsecured items in helicopters can be fatal. Doors opening unexpectedly in flight are a known risk, which is why pilots should ensure all items are appropriately secured.

Standard loading plans can save time, but to be safe the conditions specified in the plans must be clear and be met.

Aircraft manufacturers should clearly describe how maintenance tasks are to be conducted and what to expect when equipment is performing correctly.

Aircraft engineers and general aviation maintenance organisations must ensure maintenance is conducted in accordance with aircraft manufacturers’ approved repair and maintenance procedures.

When Civil Aviation Rules are clear and unambiguous, it is more likely that aviation participants will comply with them.

Cockpit video recorders, where fitted, can potentially provide valuable information on the causes of accidents and help avoid recurrences.

Safety recommendations
In December 2018 the Commission published an interim report with an urgent recommendation that the Director of Civil Aviation remind aviation participants of the importance of incident notifications in accordance with Civil Aviation Rules Part 12 – Accidents, Incidents, and Statistics (035/18).

The Commission has in this report made one new recommendation to the Director of Civil Aviation, to address the non-reporting of doors opening in flight, and one new recommendation to the Secretary for Transport that they work with the Civil Aviation Authority to resolve ambiguity in the definition of crew members in commercial transport operations.

Who may benefit
Aircraft operators, pilots, maintenance organisations, engineers, aircraft manufacturers, aviation regulators and organisations that engage operators to provide helicopter services may benefit from this report.
Wanaka (-44.712500,169.267000) [may be approximate]