WASHINGTON (Reuters) - A failed front axle on an amphibious “duck boat” led to a deadly Seattle collision between the vehicle and a charter bus that killed five international students, the National Transportation Safety Board found on Tuesday.
The September 2015 incident on the city’s busy Aurora Bridge increased scrutiny of the boat-buses, which have been involved in several deadly crashes in recent years.
The NTSB said the front axle failure resulted from a manufacturing error by the company that built the vehicle, Ride the Ducks International Inc. The board also faulted the tour company, Ride the Ducks of Seattle, for not ensuring proper maintenance.
“The chain of events leading to this crash began years before the crash,” NTSB Chairman Christopher Hart said at a board meeting. “Our investigation found missing layers of safety oversight in the way that (amphibious passenger vehicles) are manufactured and maintained.”
A lawyer for Ride the Ducks of Seattle did not immediately comment on the NTSB findings. In May, state regulators imposed a $308,000 penalty on the company after it admitted to violating 463 motor carrier safety rules.
The left axle fractured and the driver lost control of the boat-bus vehicle after hearing a loud clunk sound, the NTSB said. The vehicle involved was built in 2005 on a 1945 GMC amphibious vehicle chassis with a 1992 GM engine.
The vehicle was under the oversight of the U.S. Coast Guard when operated on water about a third of the time, but was not subject to oversight by the U.S. National Highway Traffic Safety Administration when traveling on roads, since the manufacturer had not registered with the agency.
Ride the Ducks International issued a service bulletin in 2013 to address axle issues, but never issued a recall. The NTSB called on Wednesday for an immediate recall of all similar boats to ensure axle failures did not occur.
The students killed in the Seattle crash were from Austria, Indonesia, Japan and China.
In January, Ride the Ducks of Seattle resumed operation after agreeing to use new street routes and add a second staff member to each tour.
The accident came four months after an amphibious sightseeing vehicle in Philadelphia fatally struck a woman on a street. In 2010, two tourists were killed when a tugboat pushed a barge into a similar vehicle in Philadelphia.
In April, a Boston Duck Tours bus struck and killed a woman in Boston.