NDT for Amusement Rides and Parks

What can fail, and why it matters

A roller coaster train, a swinging ship or a spinning arm ride puts the same loads through the same parts over and over — every launch, every turn, every stop. That is the classic recipe for fatigue: tiny cracks that start at welds, holes, sharp corners or areas of wear, then grow a little with every cycle until the remaining metal cannot carry the load. Axles, wheel carriers, pins, restraint components, arm and gondola connections, and the welds that join ride structures are typical places to look.

Rides also face corrosion from weather and, at water parks, from constant water exposure, as well as wear in bearings, bushings and brakes. Wire ropes on lift and drop rides deteriorate with use.

Ride incidents are rare compared with the enormous number of rides taken, but when they happen they are highly visible and can be tragic. Beyond the human cost, a failure can close a ride or a park, trigger regulatory action and investigations, and damage public confidence. Fatigue cracks are exactly the kind of damage that can be found early with the right inspection — which is why NDT is part of ride maintenance.

Where NDT is used

• Visual inspection (VT) is the daily foundation, carried out by trained ride maintenance staff before opening and at scheduled intervals. It finds obvious cracks, loose fasteners, wear and damage, and it tells the team where to look more closely.
• Magnetic particle testing (MT) is one of the most common NDT methods on steel ride components. It finds surface and near-surface cracks in axles, pins, wheel assemblies, restraint parts and welds.
• Ultrasonic testing (UT) finds cracks inside axles and shafts — often before they reach the surface — and measures wall thickness where corrosion is a concern.
• Liquid penetrant testing (PT) is used on non-magnetic parts such as aluminum components and some stainless steel.
• Eddy current testing (ET) can find surface cracks quickly, including through thin paint, on suitable parts.
• Wire rope inspection, by visual examination and electromagnetic rope testing, assesses broken wires and loss of metal in cables used on lift and drop rides.

Which components get which method, and how often, is set largely by the ride manufacturer's maintenance instructions, which typically identify critical parts, required NDT methods and inspection intervals.

How inspection fits into ride operations

Before a ride opens. New rides are inspected during manufacture and installation, and many jurisdictions require an inspection before the ride can operate.

Daily and periodic checks. Operators perform documented daily inspections, then more detailed inspections on schedules set by the manufacturer and their own maintenance program.

Off-season maintenance. Seasonal parks typically do the heaviest work during the off-season: trains and cars are disassembled, and NDT is performed on axles, wheel assemblies and other critical components according to the manufacturer's schedule. This is when most formal MT and UT happens.

After an event or modification. Unusual loads, incidents, repairs or modifications call for inspection before the ride returns to service. Repairs by welding in particular should be inspected, since weld repairs can introduce new crack starters.

Rides that move. Traveling rides are assembled and dismantled many times a year and are inspected at each new setup under the rules of the local jurisdiction.

Standards and regulations

• ASTM Committee F24 on Amusement Rides and Devices publishes the core consensus standards for the industry, including standards on design and manufacture, on quality and construction, and on ownership, operation, maintenance and inspection. Many U.S. states reference them in their ride-safety laws.
• State and local regulation varies widely. Some states have dedicated ride inspection programs and require ride registration, inspection and incident reporting; others rely more on insurers and third-party inspectors.
• Manufacturer instructions are central: they identify critical components and specify NDT methods and intervals for each ride model.
• NDT personnel performing formal methods such as MT and UT are commonly qualified under a written practice based on ASNT SNT-TC-1A (Level I, II and III), or to what the manufacturer or jurisdiction requires.

What this means for park owners and operators

For owners, three questions matter. Do we have the current manufacturer's NDT requirements for every ride, including any service bulletins, and are they reflected in our maintenance plan? Is our NDT performed by people qualified in the method, using procedures and reference standards appropriate to the part? And can we show, quickly, that each required inspection was done on time, with results and any repairs documented?

Good records protect riders first, and they also protect the business: they support regulatory inspections, insurance reviews and, if something does go wrong, a clear account of how the ride was maintained. For older rides, or rides whose manufacturer is no longer in business, an engineering review of critical components and inspection needs is a sensible investment.

How NDT LLC can help

NDT LLC helps parks, ride operators and ride maintenance providers build NDT programs, write procedures, train and qualify inspectors, and review contractor NDT. Whether you are planning off-season work or reviewing a ride's inspection history, contact us.