In recent months, there has been renewed focus in the industry relating to mast bumping accidents. Those involving Robinson Helicopters gaining much attention due to a significantly higher accident rate in the small island nation of New Zealand.
Robinson Helicopters delivered a helicopter in December of 2016 that became the company’s 12,000th helicopter produced by the Torrance, California-based company that is still owned and run by the Robinson family. Conservative estimates place the total flight hours of Robinson Helicopters around the world at approximately 35 million total hours of operation.
With the large amount of R22s, R44s and R66s manufactured by Robinson, the question that needs to be asked in the helicopter industry is, why is there such a large disparity of mast bumping accidents occurring in New Zealand, a country with just over three hundred Robinson Helicopters in operation. This compares with the United States that has 9 times as many helicopters.
The focus on accidents related to mast bumping in New Zealand has come with a flurry of news stories from sources that include industry magazines, online media sources and the print media in New Zealand. Some stories, as is often done in media circles, quote verbatim from one news source to another or quote “facts” shared on social media. Unlike stories published by helicopter industry sources, mainstream media sources have sought to sensationalize the accidents, often publishing information with little to no factual evidence to support claims and speculations made. The most common issue with the mainstream reporting of an accident is a complete lack of accurate comparative analysis that is skewed to suit a particular story narrative. While this story will likely continue to evolve, Heliweb will endeavor to continue investigating the incidents, causes, and practical solutions provided by the industry and attempt to provide a comprehensive view of the situation as information becomes available.
What we know:
The number of Robinson helicopters operating in New Zealand totals approximately 300, that number making up almost 40% of the nation’s fleet of civil helicopters. There is no question New Zealand has a problem with mast bumping accidents, the evidence plainly supports this. What mainstream sources lack to mention, is that New Zealand’s Civil Aviation Authority (CAA) had already identified the problem several years previously and was aggressively looking into the issues, making changes, and working with Robinson, pilot’s and operators, and other aviation regulators to addresses the issue collectively.
One of the issues the CAA identified was the culture towards training and flying in New Zealand differed greatly than other countries. The culture in New Zealand was in fact, contrary to that of accepted safe operations in other areas around the world. In response, the CAA began working to harmonize training to change both the operational and training culture of New Zealand.
Following an R44 mast bumping accident occurring near Queenstown New Zealand, New Zealand’s Transportation Accident Investigation Commission (TAIC) put all three Robinson helicopters on a “Watchlist”. TAIC is the New Zealand agency in charge of investigating accidents in the same capacity as the NTSB in the United States. Whether or not Robinson should have been put on a New Zealand “Watchlist” is the subject of another story. The TAIC in their watchlist specifically mentioned New Zealand’s mountainous terrain and high winds as possible causal factors.
Since 2000 there have been 8 Robinson accidents attributed to mast bumping in New Zealand. Comparing New Zealand mast bumping accident rates with the United States shows the size of the problem. The New Zealand fleet of only 300 Robinsons is dwarfed by the approximately 2,700 Robinsons in use in the United States. However, accidents attributed to mast bumping in the U.S over the same time period shows both countries have had the same number (8) of mast bumping accidents . Given the disparities in fleet size the question is why is the rate of mast bumping accidents in New Zealand, nine times higher than that of a country that operates nine times as many helicopters?
The skewed reporting on these incidents often fails to mention correct statistics that show New Zealand as having an accident rate attributed to mast bumping of 2.66% when compared to their fleet size. In comparison, in the United States, with a fleet size nine times larger, the mast bumping accident rate is 0.296%. That disparity led the CAA to further investigation and supports the CAA’s findings regarding the culture of those flying Robinson Helicopters in New Zealand. This also comports with the fact that Robinsons are being flown successfully around the world in similar conditions without showing accident rates remotely similar to those in New Zealand.
What pilots can do:
Robinson’s advice to pilots, contained in Robinson’s publications including Safety Alert 18 Nov 2016 and Safety notices SN-32, SN-29 and SN-11 set forth the precautions that must be taken to avoid low G conditions and the potential for mast bumping. Robinson advises primarily against flying in significant turbulence and practicing maneuvers that could induce low G conditions, like a “low G pushover”, which is specifically prohibited.
Secondarily, the manufacturer advises in the Safety Alert, in the event of a low G situation occurring (a lightweight feeling in the seat), the first flight control input that should be performed above all others is the application of gentle aft cyclic pressure. The Safety Alert states to respond immediately and not wait for a full low G situation. Once in a low G situtation, a resulting right roll can occur, which is the beginning of the pilot losing control of the helicopter.
The more significant point contained in Robinson’s Safety Alert and SN-32 for pilots is to slow down if turbulence is anticipated during flight. When in a high-speed nose down attitude in forward flight a Robinson, or any other semi-rigid rotor system helicopter, is more susceptible to mast bumping in low G conditions because the tail rotor of the aircraft is producing more thrust and is higher relative to the aircraft’s center of gravity.
New Zealand’s focus must change from a mentality towards blaming an aircraft design for what is shown to be the need for a cultural shift in pilot attitude, proficiency and how aircraft are flown in the country. Having flown an estimated 35 million flight hours globally since their 1982 introduction to the market, Robinson Helicopters have been involved in 291 fatal accidents, resulting in 512 fatalities worldwide as of the time of this writing. Those numbers when compared with the amount of global flight hours, equate to a less than 0.001% fatality rate or 0.0008% accident rate when compared against total flight hours. While every death is tragic, the fact remains that statistics can’t lie.
Robinson Helicopter SN-32 video
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