Questioning Single-Engine Helicopter Performance

Matt Callan 2019 Winter

Let’s focus on what causes most accidents (hint: it’s not engine failures).

While the US helicopter industry enjoys relatively nonrestrictive single­engine regulations, the rest of the world is experiencing increasingly prescriptive standards and recommended practices issued by the International Civil Aviation Organization (ICAO) that are aimed directly at limiting the operation of single-engine helicopters.

ICAO’s reasoning: if an engine failure occurs at any time during the flight, a single-engine aircraft will be forced to land. Governments that participate in ICAO are offered two choices. Either (1) restrict the operation of single-engine aircraft over congested areas (ICAO defines these as any used for residential, commercial, or recreational purposes, which ends up eliminating a lot of land, particularly in densely populated countries) or (2) implement their own performance standards for helicopter operations (which the United States, among others, has done). The result is that single-engine aircraft are being regulated out of the civil fleet in many of the 192 nations that are ICAO members.

In fact, there is no justifiable reason to portray single-­engine helicopters as being inherently more dangerous. Companies that work regularly in mountainous and high-terrain areas often use single-engine helicopters because of their superior performance under those conditions. And just like single-engine helicopters, those with twin engines have only one tail rotor, one main rotor gear box, one tail rotor gearbox, and one tail rotor drive shaft. The failure of any one of these critical components means that aircraft is going down—regardless of the number of engines.

The sad truth is that the majority of helicopter mishaps result from pilots making judgment errors, losing control of the aircraft, and flying perfectly good machines into terrain. According to the US Helicopter Safety Team, the top three types of helicopter mishaps (loss of control, unintended flight in instrument meteorological conditions, and low-altitude operations) accounted for more than 50 percent of the helicopter fatalities (104), more than the remaining 15 types combined (96).

Accident data from other ICAO-participating states support the safety of single-engine helicopters. The Australian Transportation Safety Board classified accidents over a five-year period as either mechanical or operational. Of the 749 accidents recorded during the period, just over a quarter (197) were attributed to mechanical problems. In other words, close to 75 percent of those accidents were not mechanical (that is, pilot error).

Japan, a country with a relatively small land mass and numerous mountains, is an ICAO-participating state that employs over 300 single-engine helicopters. According to Japanese aviation records, there are presently 814 registered helicopters operating in the country, with a ratio of 42.1 percent single-engine and 57.9 percent twin. Over the last 20 years, the numbers of single­engine helicopters have decreased, but the country still has many single-engine helicopters that regularly fly over Japanese airspace.

According to statistics obtained from its Transport Safety Board, Japan has not experienced a single accident or incident caused by an engine failure in the last 10 years. Once again, pilot error is the leading cause of accidents or incidents—in singles and twins. Although mechanical issues did contribute to mishaps, they were caused by detachment of the tail rotor (immune from the number of engines) and a fire in the cargo compartment.

These mishap statistics tell the same story as those from the United States: the clear majority of helicopter accidents are caused by pilot error, not by system malfunction. Wouldn’t our attention, time, and money be better spent on training pilots instead of banning single­-engine helicopters?

Instead of focusing an inordinate amount of time, energy, and resources to paint single-engine helicopters as potential high-risk operations, ICAO and its member states should instead invest in improved pilot training, risk assessment and mitigation, and crew resource ­management.

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