B.C. airlines respond to U.S. seaplane safety warning following fatal crash

Oct 30, 2022

Photo: Skytamer

The U.S. National Transportation Safety Board has identified a potential cause for the fatal crash involving a Canadian-made de Havilland DHC-3 Otter seaplane.

American air-safety regulators have identified what potentially caused a seaplane to nosedive out of the sky and crash off Whidbey Island in September and issued an urgent safety notice to other operators of the plane model, a workhorse for B.C.’s coastal airlines. Investigators from the U.S. National Transportation Safety Board (NTSB) found that parts in an actuator that operated the plane’s horizontal stabilizer — the control surfaces of the tail — had become detached, which may have caused the aircraft, a de Havilland DHC-3 operated by Friday Harbor Air, to crash over the Labour Day weekend, killing all 10 onboard.

The NTSB has issued an urgent safety recommendation to the U.S. Federal Aviation Authority and Transport Canada that the planes, also commonly known as the de Havilland Otter, be grounded until those parts can be visually inspected.“Immediate action needs to be taken to inspect the actuator of DHC-3 airplanes, of which 40 per cent operate in the United States, to prevent a similar tragedy from happening,” NTSB chairwoman Jennifer Homendy said in a news release.

The DHC-3 is a common sight on B.C.’s coast. Harbour Air regularly flies several out of Vancouver Harbour on its regular daily routes. Vancouver Island Air also employs the planes. Transport Canada is in the process of releasing a Civil Aviation Safety Alert highlighting the inspection requirement, according to an emailed statement in response to Postmedia News questions. And Victoria-based Viking Air, which holds the airworthiness certificate for de Havilland aircraft, said it has already issued a service letter to operators of the plane to visually inspect the problem parts.

“A number of the operators had already been doing that, but we formally (issued the letter Oct. 27),” said Neil Sweeney, vice-president of corporate affairs for de Havilland Canada at Viking.

Vancouver Island Air declined to comment. Harbour Air didn’t return Postmedia phone calls, but in an emailed statement vice-president of marketing Meredith Moll said maintenance staff have returned all 22 of its Otter aircraft to service after completing the additional inspection. Sweeney said the NTSB asked Viking engineers to participate in the investigation, which is common practice for aviation firms.“Our engineers would provide the drawings and provide advice as to what is normal and what you should find in an intact circumstance,” Sweeney said.

In this case, according to the NTSB bulletin, investigators found in examining the wreckage a clamp nut at the top end of the actuator’s assembly had become unscrewed, likely during flight, and a wire lock ring designed to prevent the nut from coming loose wasn’t present. Sweeney said the inspection found the critical nut unscrewed, but the threads it attached to were intact “which, to them, suggests that the mechanism came apart, not as part of a crash, but prior.”

The NTSB’s urgent notice said the Sept. 4 incident involved a Friday Harbor Air Otter, which took off from its base and reached level flight, continuing for 18 minutes before climbing slightly then plummeting about 1,000 feet in a near vertical dive into the water of Mutiny Bay. The Seattle Times reported that witnesses observed the plane spinning on the way down but without any “pitch change” to the engine’s sound during the descent. Sweeney wouldn’t comment on the NTSB’s preliminary findings in this crash specifically but said, generally, that the work of regulators to identify the causes of crashes “is invaluable to us.”

Manufacturing of the Otter, most of which were built in the 1950s and ’60s, was discontinued decades ago, but Sweeney said 161 of the 466 made are still flying and Viking still puts considerable resources into making sure the planes remain airworthy and manufactures spare parts. Despite the age of remaining aircraft, Sweeney said that because they’re not pressurized during flight, “there’s no end date, or best-before date” on the airframes, so long as they’re properly maintained.

(Source: Vancouver Sun, Derrick Penner)

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