Following the catastrophic failure of a bolt on a North Wales limestone route, the BMC is advising climbers to treat all ‘Thunderbolt’ anchors with caution. Read on for more details and advice on how to detect these bolts.

The bolt that failed was the first bolt on the route "One Ard 1-Der" a 6b sports route at the newly developed Craig Heulog on the West Shore of the Great Orme. The bolt that snapped was the first bolt in a four bolt route and snapped cleanly when the leader fell off while above the third bolt - therefore there was no direct fall onto the failed bolt, only the slight sideways tug of the quick draw as the rope went tight. This implies that the bolt failed at a low load.

Until a more thorough investigation is undertaken its not known what the cause of the failure might be. Until then, its advised that climbers treat all bolt placements with "Thunderbolt" placements with great caution. Enquiries and investigations are underway with first ascentionists and other route developers in North Wales to establish the extent of the problem. It's known that both this route and another adjacent route "Simpl-City" 6a both use these type of bolts, but these bolts will have been removed by BMC volunteers by this time.

The manufacturers of "Thunderbolt" have categorically stated to the BMC that this product is not tested or recomended for the purposes of fixing climbing anchors.

It's possible that other recently developed routes at Castle Inn, Penmaenbach Quarry and other North Wales limestone venues may have been equipped with similar bolts. The routes known to have been equipped with these bolts were developed in late 2011 and its likely that only routes developed at that time or since that date are affected.

How to identify "Thunderbolt" bolts

• "Thunderbolt" bolts are self-tapping threaded bolts with a fixed hexagonal gold coloured head. The one that snapped was an M8 x 100mm that had been placed in a drilled hole and resined in place with a Petzl hanger placed on the bolt. The hanger did not fail - the failure appears to be a clean break of the bolt itself, some 14mm in from the hexagonal bolt-head, inside the drilled hole.
• The bolt head is embossed with the letters "APT" and "8 x100".
• Conventional expansion bolts used on North Wales sports routes  tend to use 12mm "through bolts", where the nut that hold the hanger in place is separate from the bolt itself (see photos)
• With the "Thunderbolts" the bolt head is flush with the hanger (see photos).

This issue will be discussed at the next BMC Cymru North Wales area meeting on Tuesday 4 June.

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