If it's a bad batch, it's the same "batch" that has been failing for at least 20 years leading to some serious accidents. In some cases, 50's -60's time frame, they were used in flight controls and if you were very lucky the connecting bolt didn't fall out in flight. Some years ago Hiller issued a SB to remove the standard bolts and L series nuts and install drilled bolts, slotted nuts and split pins. They seem to be OK in fixed wing designs but I'm not sure they should ever be used in helicopters, at any location.