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Structural Failure of Black Diamond Ultralight Camalot Size 0.4 Resulting in Injury


Original Post
Brian Braunstein · · Zürich, CH · Joined Oct 2016 · Points: 85
Summary
A confidence inspiring placement of a Black Diamond Ultralight Camalot Size 0.4 failed in an unexpected situation resulting in an injury.  Given the circumstances and preliminary conclusion, anyone using smaller size dual axle cams may want to reconsider what cams to include in their rack, or reconsider how this gear is placed.  In particular, tighter yet not over cammed placements will make use of a thinner and therefore weaker part of the lobe on dual axle cams, since a hole is needed in the lobe in order to accommodate the opposite axle while pivoting.  This weaker section of the lobe deformed in the scenario outlined here, reducing camming action, which is the likely reason for failure.

The Scenario
A Black Diamond Ultralight Camalot Size 0.4 was placed in a granite crack with good rock on the climb “Neat and Cool” in Squamish, just before the first leftward traversing crux.  The placement seemed very confidence inspiring to a leader experienced in placing gear and who has fallen on cams countless times.  The placement was deep enough to allow for some amount of sliding and movement before catching, the crack wasn’t particularly flared, the rock seemed of good quality and is clean due to the popularity of the route, and the cam lobes were somewhat tightly compressed but not what one would normally consider a risk for getting stuck due to over-camming.  The surrounding rock is notable for having slightly more texture and shape than “standard” Squamish granite, but the placement in the crack seemed to fit well.  The orientation of the cam was slightly left, which oriented it more towards where the fall would initially start to catch due to the left traversing nature of the climb, but not in the directly downward direction where the greatest forces would likely be exerted.  This orientation was picked mainly to ensure the placement fit well to the shape of the crack while still being reasonably oriented.  The cam was extended with a non-extended 60cm "trad draw", so 20cm plus carabiners plus the stock sling on the cam.  The rope was a 9.2mm Mammut Revelation.
The Fall
A few seconds before falling, the climber communicated to the belayer that the fall would likely occur, which allowed the belayer to be ready to give a slightly dynamic catch.  The belay and climber both weight about 70kg.  The fall was an intentional release from about 1m above the placement with about 10m of rope out and insignificant rope drag.  The fall initiated slightly left of the cam placement but without significant pendulum risk.  Those familiar with the climb might expect a higher pendulum risk, but the climber incorrectly tried to go up, with the fall occurring with right hand on the platform more directly above the cam placement.  Upon falling, the size 0.4 cam failed and shot into the shin of the falling climber, resulting in injury requiring medical attention including stitches.  A size 1 Black Diamond Ultralight Camalot caught the fall, keeping the climber several meters off the ground.

The Failed Cam
Inspection of the failed cam showed that one of the lobes was stuck in the closed position due to a deformation, which caused the lobe to catch on the opposite axle preventing it from opening up.  The deformation of the lobe occurred where the lobe is thinner due to the hole needed to allow the opposite axle to slide through while pivoting.

This cam was nearly brand new, purchased 2 months prior, receiving very light use, having caught either 0 or 1 prior lead falls.  The manufacturing code is 7054-2.
Theory of Failure
The theory discussed among the experienced climbers that witnessed the event is that the cam failed due to the weaker part of the lobe compressing and deforming, resulting in loss of sufficient camming action.  The slightly left orientation of the placement may have caused it to move somewhat while catching, which could have oriented the deformed lobe into a position in which it received a pressure point rather than more evenly distributed pressure, but this is pure speculation.

Conclusion
Based on the theoretical mechanism of failure, it may be reasonable to consider avoiding placing smaller sized dual axle cams tightly such that the thin part of the lobe is in contact with the rock.  This reduces the effective range of the cam and makes one consider if it’s perhaps sensible to not use smaller size dual axle cams at all, since this diminishes their main advantage of increased range compared to single axle cams.




Edited 2018.08.11:
- Added information about the extension sling.
- Added the sentence explaining why there wasn't a pendulum risk due to accidentally climb up instead of traversing left.
- Added climber and belayer weights and rope model.
Brian Braunstein · · Zürich, CH · Joined Oct 2016 · Points: 85

Here's a picture of the mess at the bottom

Mark Verosky · · Columbus, OH · Joined Feb 2017 · Points: 30

This only confirms my bias for Mastercams in this size range.

Glad he backed up his pieces and it only resulted in a minor injury. Stay safe. 

Yannick Gingras · · On the road, mostly Southwest · Joined Sep 2015 · Points: 10

Great write-up, Brian. I am familiar with the climb and this traverse always spooked me a bit. Now I will be sure to protect it with single axle cams only!

tom donnelly · · san diego · Joined Aug 2002 · Points: 255

I don't see the reasoning for the cause to be due to the double axel.
It seems that it failed due to the metal deformation in that lobe.  So doesn't that mean that if the cam were strong enough in that zone, it would not have failed?
So not all double axel cams necessarily have the same issue.  Is the ultralight lobe lighter than the regular C4 lobe?  Or did the C4 recently start using the same light lobes?

Although - I too also usually prefer other cams in the Camalot .3 & .4 size range.

Stiles · · the Mountains · Joined May 2003 · Points: 840

Are you holding Black Diamond liable?

Aaron King · · Unknown Hometown · Joined Feb 2018 · Points: 0

Is my X4 okay to use?

Max Rausch · · Portland, OR · Joined Jul 2014 · Points: 130

I never understood the point of buying the UL .4 and even .5.

Pavel Burov · · Russia · Joined May 2013 · Points: 50

@Brian, could you estimate whether the deformed lobe was the lowest one or not?

Carolina · · Farmington, nc · Joined Nov 2010 · Points: 75
Stiles wrote: Are you holding Black Diamond liable?

How would you? Lawyers up? Meal ticket?

Mike · · Unknown Hometown · Joined Dec 2013 · Points: 10

You're either indicating that the lobe was deformed prior to this placement which inspection should have caught or you're saying the cam deformed during this fall with compression and then ripped.

 The second being unlikely and would require the cam was poorly placed already and rotated into a worse position after deforming or rock breaking since the force required to deform the load is the same force that catches the climber.

I hope the injured climber heals quickly but this isn't the cam's fault.

patto · · Unknown Hometown · Joined Jul 2012 · Points: 25

Great report Brian Braunstein.  I agree with your analysis and conclusions.

The possibility of this mode of failure was recently mentioned on Mountain Project.  In might have even been seen in test jigs, I'm not sure.  But I remember it being mentioned in the last 6 months.  I haven't heard of it occurring in the wild until now.

One question for anybody that can answer it.  Are BD UL lobes different to regular C4s?

Mike wrote The second being unlikely and would require the cam was poorly placed already and rotated into a worse position after deforming or rock breaking since the force required to deform the load is the same force that catches the climber.
You are not making sense here.

Mike wroteI hope the injured climber heals quickly but this isn't the cam's fault.

The lobe deformed under compression from a relatively minor fall.  Your conclusion does not seem to follow.  Cams lobes should not be plastically deforming at loads well under what they are rated to hold.

(A non parallel, tapering crack can lead to higher compression on lobes than normal camming angles would predict.  But well designed cams should have no issue with this.  A cam with minimal meat at the lobe contact point is an issue.)
Jake Jones · · Richmond, VA · Joined Jul 2011 · Points: 1,659
Max Rausch wrote: I never understood the point of buying the UL .4 and even .5.

The percentage of weight reduction in these sizes from C4 to UL is significant because the steel cable in the C4 accounted for a lot of the weight.  However, because these are still fairly light units compared to bigger cams, the overall weight difference isn't huge.  That may be the reason.  Personally, I don't like the seemingly extra stiff stems of the ULs, so the smallest I have is #1.  IMO, when you're placing small cams and want them to stay put, a more pliable stem will help the head and lobes stay put, especially if you extend them.

patto · · Unknown Hometown · Joined Jul 2012 · Points: 25

Here is a brief discussion on this very topic:
https://www.mountainproject.com/forum/topic/114480508/overcammed-cam-is-weaker?page=2#ForumMessage-114487520

Tony B wrote: 
Small BD Camalots used to get damaged if loaded hard at 90-100% retraction, as the dual axle blue-grey models had such thin material at the lobe at that point.
But it didn't make the placement fail, ISFAIK... it just meant you'd never use them again, if you could clean them at all.

rgold wrote:
This is a point I overlooked in my comments.  I've never heard myself of one of these cams failing, but the material at close to full retraction is indeed very thin!

Tony B wrote:
I've retired a few that were not even fallen on because the material was bent into the axle and the cam was ruined.
Just a 2-lobe aid placement or aggressive cleaning was sufficient to collapse the material inward on those and make a detent in the lube from axle contact.
Doug Kinsman · · Atlanta, GA · Joined Jun 2008 · Points: 0

Interesting for sure. You note that this rock has slightly more texture than typical of the rock in the area and I have to wonder if a crystal was sticking into the cam at the deformation point. I had that happen with a green alien that blew and the deformation/flattening of the lobe looks very similar to yours in spite of the alien lobes being solid with no "weight saving" material removed (kind of impossible to window an alien lobe). One of the alien lobes was on a slight crystal that looks like it punched into the cam lobe when I fell and blew the piece which miraculously caught again about foot further down the crack.

highaltitudeflatulentexpulsion · · Colorado · Joined Oct 2012 · Points: 35

I've seen this on c4 too. I might have a few in the garage in this condition. Enough use and the .4 and .5 will eventually have this deformation.

I usually use aliens though.

John Wilder · · Las Vegas, NV · Joined Feb 2004 · Points: 1,535

Having climbed the route in question a few times, I have a question and two comments.

 was this piece extended?

This particular piece is pretty critical as a fall from far to the left of it would be really bad if it failed. I'm not sure you'd stay off the ground. It also happens to be a touchy piece to get and, as I recall, I don't use a 0.4 there because it's not a super good placement. My memory fails me exactly what piece I use, but I want to say it's something slightly smaller in that area.

If the piece isn't extended (and I see people not extend it all the time because the following sequence isn't obvious and it's spooky)- that cam will walk, guaranteed. You move straight left about 10' and then straight back to directly above the piece.

Small cams have small room for error. An inch of walking and the placement could be compromised. While I think the damage to the lobe isn't awesome, I don't think that would cause the can to rip. I suspect that was incidental here.

patto · · Unknown Hometown · Joined Jul 2012 · Points: 25
John Wilder wrote: While I think the damage to the lobe isn't awesome, I don't think that would cause the can to rip.
Compressive flattening of a cam lobe can readily lead to failure.  Your claim isn't based in experimental reality or in theory.

John Wilder wrote:
Small cams have small room for error.
That might be true, but it isn't the issue here.  Nor in my book is a 0.4 a 'small' cam.  What constitutes a small cam might be up to an individual, I have 6 sizes above the 0.4 BD and 5 sizes below.  So on my rack it is a middle sized cam.
Tradiban · · Unknown Hometown · Joined Apr 2004 · Points: 11,455

Sounds like the piece was placed perpendicular to the fall and was not properly extended.

BigRed11 · · Unknown Hometown · Joined Apr 2013 · Points: 831

I've had a yellow mastercam rip in almost exactly the same placement. Also looked textbook. I would imagine this failure is a function of a cam that walked (like mine probably did) rather than a structural issue with C4s. I would imagine that BD engineers have run various analysis on that part of the lobe, being the obvious weak point, to make sure it could withstand expected loads.

Guy H. · · Fort Collins CO · Joined Jan 2001 · Points: 7,412

I will not use my 0.4 UL, since the stem is almost the same size as the cams in a tight placement.  I could see a case where the cam is levered out of the placement with the rigid stem.

Guideline #1: Don't be a jerk.

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