Relatives of six Canadian Armed Forces personnel killed in a 2020 helicopter crash are suing aircraft manufacturer Sikorsky, alleging a flaw in the CH-148 Cyclone’s fly-by-wire flight-control system caused the incident.

The suit, filed in a US federal court on 10 July, alleges that the CH-148’s electronic flight-control system (EFCS) overrode pilot commands, plunging the Royal Canadian Air Force (RCAF) helicopter into the Ionian Sea at high speed.

Royal Canadian Air Force CH-148 Cyclone helicopter lands on Royal Canadian Navy ship c RCAF

Source: Royal Canadian Air Force

The 2020 crash of a RCAF Sikorsky CH-148 Cyclone helicopter in the Mediterranean Sea killed six Canadian personnel

The civil court filing says the EFCS – also known as the flight director – was engaged to maintain airspeed, backing up manual input.

“As the pilots completed a multi-axis, low-altitude manoeuvre using manual pedal and cyclic inputs, the CH-148’s EFCS took control away from the pilots and pitched the helicopter’s nose down, accelerating towards the water,” the lawsuit alleges. “The EFCS completely overrode the pilots’ attempts to stop the descent.”

The 2020 incident occurred 77nm (142km) off the coast of Greece in the Ionian Sea. An investigation by Ottawa confirmed that the CH-148’s flight director was engaged to maintain altitude and airspeed at the time of the crash.

Examination of flight data recovered from the crash led investigators to rule out mechanical failure.

“During the complex manoeuvring turn to align with the ship, the pilot’s inputs were significantly different from the autopilot settings and the aircraft did not respond in a way that the crew was expecting,” Canada’s Department of National Defence concluded.

The investigative team described the error as a “rare anomaly only” that occurred “under a very specific and narrow set of circumstances… The crew would have had no previous exposure or experience on how to handle this situation”.

Sub-Lieutenants Matthew Pyke and Abbigail Cowbrough of the Royal Canadian Navy, and Master Corporal Matthew Cousins, Captain Kevin Hagen, Captain Maxime Miron-Morin and Captain Brenden Ian MacDonald of the RCAF, died.

Their families are suing Sikorsky and fellow Lockheed subsidiary Helicopter Support for financial damages related to the deaths under the USA’s Death on the High Seas Act (DOHSA). Each of the six plaintiffs – one representing each of the Canadian service members killed – is seeking “an amount greater than $75,000… that the court deems just”.

The 2006 law allows spouses, children, parents and legal dependants of people killed by “wrongful act, neglect or default”, more than 3nm from US shores, to bring civil actions against the “person or vessel responsible”.

The families sued in US District Court for the Eastern District of Pennsylvania, in Philadelphia. Sikorsky is headquartered in Connecticut, but the lawsuit notes the helicopter maker identifies its facility in Coatesville, Pennsylvania as “the Home of the CH-148.”

At that site, Sikorsky “assembled, upgraded and conducted the final flight acceptance tests on the Incident CH-148 Helicopter,” legal documents claim.

Notably, the families do not allege that the EFCS malfunctioned or mechanically failed. Instead, the suit argues a defect in the design of fly-by-wire system “repeatedly and consistently resulted in a fatal crash” during test conditions similar to those experienced during the 2020 incident.

“At the time of the incident, Sikorsky’s EFCS was performing exactly as Sikorsky had designed it,” the lawsuit claims.

Sikorsky did not respond to a request for comment.The CH-148 is a military derivative of Sikorsky’s S-92, a twin-engined medium-lift helicopter used widely in the oil and gas industry.

Separately, in 2021, the RCAF found tail-section cracks in 21 of 23 CH-148s. The issue was determined to be caused by in-flight structural loading on electronic support measures and satellite communication antenna mounts.