‘The squirrel’ flies

LIHUE — The helicopter involved in a fatal crash last week near the NaPali Coast has a nickname.

The Eurocopter AS350 Écureuil — French for “squirrel” — was one of several models in a series of helicopters designed and manufactured in France by a pair of companies that became part of Airbus Helicopters, the industry’s largest manufacturing corporation.

Helicopter pilots call the AS350 “the squirrel” at least in part, because of the model’s notoriously touchy controls, according to Preston Myers, the founder and owner of Safari Helicopters, after one of the company’s tours ended disastrously last week.

Nearly 20 years ago, Myers was preparing to take off in the very same helicopter that went down with seven people aboard last Thursday afternoon, when he suddenly lost control of the machine during routine preflight checks while still on the ground at Lihue Airport.

In the accident report, Myers said the helicopter suddenly “became airborne in nose low altitude.” He tried to pull the aircraft around to face the wind and attempted to take off, hoping to pick up speed and regain control of the aircraft. The helicopter responded by tilting back and to the side, immediately going into, what Myers described as, “a figure 8 type of oscillation,” with the nose rapidly pitching up and down “in extreme, almost-wing-over attitudes.”

Myers said in the report that he determined the problem was related to the helicopter’s hydraulic system, which he decided against shutting off out of concern that the pitching aircraft would end up in “inverted position.” By this point he had “no control responses,” but, for lack of a better option, decided to “ride the situation out.”

Then, Myers wrote, the helicopter started to descend like a falling leaf. It struck the ground tail-rotor first, and Myers’ report says he heard a “series of grinding sounds,” until the helicopter came to rest on right side and the main rotor blades “literally disintegrated upon impact.”

Myers was the only one on board at the time and walked away from the crash, but the helicopter didn’t fare so well. According to the report, the crash destroyed the tail rotor gear box, blades, tail boom and main rotor system, along with the right skid and sliding door.

In a second paragraph, following his description of the incident, Myers included his “personal opinion,” recommending ways manufacturers could improve the helicopter model’s design so as to prevent similar incidents in the future.

Among the concerns Myers mentioned in the report was an issue with the AS350’s main fuel tank, which he pointed out lacked baffles, or a system of barriers, to “reduce fuel slosh” that could potentially destabilize the helicopter, a design oversight he said, “contributes (to) this aircraft’s nickname, ‘the squirrel.’”

Myers went on the note that the “fuel slosh” could be particularly dangerous in situations when the helicopter’s hydraulic system either malfunctioned or could not be used.

Pump and pulley assemblies that provide all the hydraulic power for the main and tail rotor controls on the AS350 failed so frequently over the next seven years that federal aviation safety officials were compelled to address the issue.

In a 2008, the National Transportation Safety Board issued a report based on the investigations of six incidents in the same number of years, including two fatal accidents, involving Eurocopter AS350 series helicopters.

The findings of those investigations raised concerns among NTSB investigators, who found that connections in the helicopter’s rotor control system displayed excessive wear, causing a loss of hydraulic power, which “hinders helicopter control and increases the possibility of a serious accident.”

The helicopter can be flown manually, without hydraulic power, according to the report, but “doing so increases the physical demands on the pilot and can cause a serious accident” if they are uncomfortable operating the aircraft manually or if the failure occurs suddenly, especially during a critical maneuver.

Other issues with the AS350 have also prompted responses from federal regulators, most recently in 2018, when the Federal Aviation Administration issued an “airworthiness directive” regarding several helicopters in the series, including the specific model involved in last week’s crash, spelling out new requirements for inspecting tail rotors and pitch rods in the helicopters.

The directive concluded that an “unsafe condition exists and is likely to exist or develop on other helicopters of these same type designs” and could result in mechanical failures “and subsequent loss of control of the helicopter.”

AS350 series helicopters have been involved in 18 fatal crashes since 2010, according to the NTSB’s aviation accident database.

In an interview Thursday, Myers told The Garden Island he was instructed by NTSB investigators not to discuss the crash but said the AS350’s mechanical issues were only a problem for pilots who had not been properly trained on the aircraft.

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Caleb Loehrer, staff writer, can be reached at 245-0441 or cloehrer@thegardenisland.com.