I was on my way home as usual one evening and just as I was accelerating away from an intersection right around the corner of my house, I felt my left pedal give... the whole left hand crank arm gave way and was swinging freely independently of the right. Something was wrong. I immediately thought it was the cotter pins that had given way, however they were nice and tight... I was able to have a look when I got home and it appeared that the BB axle had split in two somehow.
So, off with the drive side crank...
And it appears that I was correct, the axle itself had sheared right through somehow. Thankfully this didn't happen when I was pushing hard on the pedals out of the saddle or it could have resulted in an accident. The bearings were a little rough as well, not a good reflection on the quality of this piece.
It wasn't that long ago that I had specially sought out this BB, as it's quite difficult to get a sealed cartridge BB with a cottered axle. Luckily I was able to find a replacement unit, this time I went with a brand name Sunrace/Sturmey Archer unit. I've generally had good experiences with the Sunrace gear, as they make all the modern Sturmey Archer stuff. Hopefully this unit will last as long. As a side note though, the drive side offset is slightly better, this moves the chainline in a few mm now so it's about 42mm which is even better than before when it was 44mm.
All done! This is the first time I've ever broken a BB axle or anything in the crank area. Hopefully this BB should last a while yet as I hate fiddling with cotter pin cranks.