Chairlift Detachment - Attitash Mountain Resort, NH, USA

[dold]

https://unofficialnetworks.com/2025/02/03/details-emerge-attitash-chairlift-detachment/
https://liftblog.com/2025/02/02/chair-falls-from-lift-at-attitash/

More of a maintenance and inspection failure, but interesting photo of the failed part. I'd be interested to hear some of the materials / mech folks' take on that.

Lots of blame going to Vail Resorts (for those not in the know - Vail is the evil megacorp that has bought up tons of small and large resorts across the US and other countries, then hit the "maximize profit" button) for deferred maintenance, lack of training, etc.

Some reports on facebook groups from skiers who were on the lift at the time of failure indicate that the lift faulted at least once and the lift operators kept resetting the faults without much ado.

This failed part is part of the mechanism that attaches / detaches the chair from the rope while going through the terminal, and otherwise holds the chair in place on the rope. Several lift maintenance folks online have said that the wear on the grip that you see is abnormal and indicates misalignment of the grip as it goes through the terminal. The failure surfaces are pretty apparent and pretty corroded. Wild that this was never caught in an inspection.

Interesting discussions on reddit too. Insight from lift operators and lift maintenance/inspection folks.

https://www.reddit.com/r/icecoast/comments/1igqgia/attitash_ski_lift_grip_that_fell

https://www.reddit.com/r/skiing/comments/1igr10p/attitash_ski_lift_grip_that_fell_on_22

Failed part (source: reddit). A more zoomed out photo would be nice.


Failed surface shown in red on full part. Not the exact same model of grip but similar. (source: reddit)



Chair as it lay. Guys is alive (source: liftblog https://liftblog.com/2025/02/02/chair-falls-from-lift-at-attitash/)

 

[SWComposites]

Yeah, and turbine blades go thru way more detailed inspection and process control than I suspect these chair lift parts do.

 

[XR250]

Yet it happens every day because engineer approved SOP's allow it within certain criteria. Can never discount what maintenance shops on site do as well. Weld repairs on critical castings can be done properly with no issues.

It most definitely is a casting. I cannot imagine a machine shop would go out of their way to machine in a parting line mismatch and evidence of gates.

"Can be done" yes - with a qualified welder. Are getting that in the field in a ski area - probably not.

 

[DirteJoe]

"Can be done" yes - with a qualified welder. Are getting that in the field in a ski area - probably not.

No, probably not. Doesn't ever stop people from working on stuff they have no business working on. I've seen it far too often, and usually ends catastrophically. Biggest thing isn't a qualified welder though, but having the proper facilities to post weld heat treat and stress relieve.

 

[IRstuff]

Let's not forget that these chairs are detachable, and the clamp is fully separable from the chair itself.

There is ZERO need for in-field repair, since the most likely SOP is to remove the clamp, replace it, and ship the broken clamp to the factory or repair facility.

 

[IRstuff]

Let's not forget that these chairs are detachable, and the clamp is fully separable from the chair itself.

There is ZERO need for in-field repair, since the most likely SOP is to remove the clamp, replace it, and ship the broken clamp to the factory or repair facility.

I expect there's a few spare chairs and clamps floating around in the resort for occasions like this.

 

[btrueblood]

You can see beachmarks in the image above, where it's clearly a fatigue progression of a crack. Corrosion is still possible on "stainless" alloys, they are more typically described as "corrosion resistant steels", or CRES. For the discoloration, in beachmark gradiations like in the photo, you would need to surmise multiple heat events (multiple weld repairs?).

 

[DirteJoe]

Multiple heat events is what you'd expect to see on a weld repair of a casting in that area. Losts of getting it red or near red followed by cooling. That much discoloration could also be due to an incomplete repair. Why grind out the entire crack when you can just do 1/4" to 1/2" deep and cover the crack? Especially on stainless castings, you'll get the fusion zone cracking right in half rather than cracks at the weld interface or HAZ during the cooling period after a repair, often right as the weld has been completed between passes. Depending on how hot it gets between passes, there may be evidence of sugaring at the crack that often gets covered up as

 

[Tomfh]

What’s the basis for saying it’s a failed weld repair. It appears to be fatigue cracks that gradually widened until the remaining part fractured abruptly. Perhaps it was a defective component or misaligned somehow.

 

[DirteJoe]

In my opinion it looks as if it's been heated and painted with spray galv, which may indicate a weld repair. Considering Vail's history of negligent maintenance practices, it feels fitting. This is not their first lift to fall from broken, previously repaired, or misaligned components. The manufacturer has also checked out their lifts in the past, as they are again this time, and I believe they'll most likely find similar signs of negligent repairs.

 

[FacEngrPE]

Enlarging the picture posted by the OP, I see a fatigue crack (more resolution would be helpful), but no weld.
Do these hangers get any periodic NDE? A dye penetrent test would find this. A visual inspection might not.

 

[dold]

I recall seeing 10%-20% annual NDT for these components or assemblies. But that's from random Internet forums. I'm sure inspection programs are codified or otherwise published somewhere. I have not looked for them.

I'm definitely not seeing anything that looks like a weld or repair near the fracture or anywhere else for that matter. I can't imagine a part like this being repaired in the field or shop at the hill. Just take the chair off the line and throw it in the defective pile. They have spares. Send the part back to manuf.

Looks like a crack that has existed for several seasons and wasn't caught in inspection. The progression in the photos is pretty obvious IMO.

 

[Stick.]

This reddit comment from someone who claims to be a lift mechanic at another mountain says that the "grips are taken off once every 4 years at most, rebuilt and NDT particle tested for cracks." That same user also says they work on the same grips that failed at Attitash. I'm assuming that most ski mountains don't set their own NDT inspection frequencies and just follow manufacturer recommendations (please correct me if that's wrong), so the grip that failed probably should have been inspected pretty regularly.

Additionally, this press release from the New Hampshire Fire Marshall indicates that the lift is required to be inspected yearly, "with additional inspections randomly conducted during the year." It also indicates that the state inspectors will be reviewing inspection records, which I would assume/hope would include any NDT records for this or other grips on the lift.

 

[Tomfh]

So, a faulty casting that passed thru a lacklustre inspection regime. Unsurprising.

which I would assume/hope would include any NDT records for this or other grips on the lift.

I'm sure they're being busily prepared as we speak