What Caused the Crack in Carowinds’ Fury 325 Roller Coaster?
Posted 7/19/2023, Updated 8/1/2023
Last week, it was confirmed that another “weld indication” (break or crack) was found on the Fury 325. There is not yet a timeline for reopening the ride.
In a statement, Carowinds said, “During such reviews, it is not uncommon to discover slight weld indications in various locations of a steel superstructure. It is important to note that these indications do not compromise the structural integrity or safety of the ride,” the statement reads. “Once a repair is completed, it undergoes inspection and approval before the ride is deemed operational.”
The steel support column that was damaged in June has been replaced.
Looking to ride the “tallest, fastest, longest” roller coaster in North America this summer? There may be a crack in your plans.
In late June, a crack in a column of the Fury 325, a 95 mph “giga coaster” threatened the safety of passengers at Carowinds Amusement Park in Charlotte, North Carolina. The crack was likely apparent for a week before a now viral video posted by a park patron encouraged the park to shut down the ride.
The damage probably came as a surprise considering the Fury 325 had just passed its annual inspection in February with only a few (quickly corrected) problems with signage. The park’s maintenance department performs a variety of maintenance checks that occur on a daily, weekly, monthly, and annual basis. During some of these checks, technicians disassemble, inspect, test, and rebuild cars and trains for rides. Regular condition monitoring activities also include x-ray, ultrasonic, accelerometer, and magnetic particle testing. For enormous rides like the Fury 325, these checks can take up to 1,600 person-hours.
Following the ride closure, the park’s maintenance department and engineers from the firm who designed the ride, Bollinger & Mabillard Consulting Engineers, performed a root cause failure analysis. It was determined that the column cracked along a weld line; this is likely why the crack was not caught sooner. Weld flaws are an unpredictable failure.
Welders who make parts, such as the support column, are certified experts whose work is inspected by third parties. Even if welds are inspected, a crack in the weld or an air inclusion may be hard to spot, and these flaws can easily propagate.
The roller coaster is still closed while these teams work on replacing the column and thoroughly inspect the ride further, looking at all the track, columns, and the foundation. Following the incident, Carowinds will implement additional preventive maintenance efforts to ensure similar failures do not occur in the future. This will include regular visual inspections employing drones to get a closer look at areas that are hard to reach for park personnel.
The plan is to replace the support column and follow up by performing accelerometer tests which employ sensors to measure vibration. After this, Carowinds will run the coaster for 500 full cycles while simultaneously running more tests on the entire structure to ensure its integrity. They will contract out a testing firm to complete the final inspection.
A YouTube video on Carowinds’ channel showing the construction of the Fury 325 coaster reveals that ultrasonic flaw detectors were used for condition monitoring before construction was complete. Engineer Darrell Richards explained to DesignNews that engineers cannot always predict the load, so engineers pad designs with surplus strength and load-bearing capacity. Then, each support is backed up with alternate load paths.
A problem with failures such as this one is that fatigue is invisible until it has already started to happen. When it starts, evidence such as rust stains from cracked paint is apparent, as well as other indications that can be picked up by a well-trained inspector.
Although the failure was not prevented, these precautions did prevent that failure from causing a tragic accident.
According to AP News, North Carolina Department of Labor Commissioner Josh Dobson said he is “very pleased” with Carowinds’ efforts to repair the crack on the Fury 325 and improve its routine inspection process. The NC Department of Labor have been on site and are continuing to investigate how the damage occurred and why the ride stayed open for such a length of time after discovery.
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