Aviation Case Study:

28 November 2018

The Commission’s work: what we said

In October 2016, the Commission placed an item on its Watchlist titled Robinson helicopters: mast bumping accidents in New Zealand. The item was developed in response to a series of 14 accidents or incidents involving these helicopters (investigated either by the Commission or by the Civil Aviation Authority), including nine where low-G mast bumping is known to have occurred.  Eighteen people died in the 14 accidents, including nine in known low-G mast bumping accidents.

The item was placed on the Watchlist because: the Commission was concerned about the frequency of these accidents (six occurred between 2015 and 2016), the low-G related accident rate in New Zealand is considerably higher than in other parts of the world, and some of the Commission’s related recommendations remained open.

The sector response: what happened

The Commission sees good progress towards implementation of the actions we were seeking when we first placed this item on the Watchlist. For example, in a recommendation to the Federal Aviation Authority, the Commission had called for further research into the factors that can lead to mast bumping. The Robinson Helicopter Company has taken on this task, partnering with the University of Maryland to research the rotor and flight dynamics that drive aspects of mast bumping. The study will also attempt to improve resistance to mast bumping through design. An initial report has been produced and the research is continuing.

Similarly, the Commission recommended that the Secretary of Transport promote, through the International Civil Aviation Organization, the need for cockpit video recorders and/or other means of data capture in certain classes of helicopter to help better determine why these accidents happen. The Commission also gave notice to the Director of Civil Aviation that the recommendation had been made.  The Civil Aviation Authority has advised it will initiate an assessment paper on the issue including a cost benefit analysis. Robinson Helicopter Company has advised the Commission that it is currently developing flight video recorders and flight data recorders for installation into its helicopters. 

Impact: what difference have we made

The Commission is encouraged by the efforts taken by the sector since this safety issue has been placed on the Watchlist, particularly the manufacturer’s response to our recommendations, and its demonstrated commitment to safety. The manufacturer’s research initiative, and its development of flight video recorders and flight data recorders will contribute to better understanding of how mast bumping accidents occur. Although the machine design is just one aspect of this safety issue, these actions will add significantly to the international body of knowledge about how to reduce the risk of these accidents.

The sector must continue its efforts to reduce the risk of mast bumping accidents occurring.

[This case study is drawn from the Commission's 2017/18 Annual Report, and references a Watchlist item both available under Related links.]