PG&E C-hooks interpretation by an actual hydrometallurgist

pg&e-hooks-info.txt

The transposing of the lines are from right to left, left to middle and
middle to right (camera-side to far-side). The  failed one is on "from right
to left".  The wear pattern (picture with red parallel lines) tells me that
the C-hook is not made of cast iron but made of cast steel because cast iron
is hard and strong but it is so brittle that when it breaks, it will go in
one clear break (full face) and not in the pattern as seen
(wear-wear-wear-then tear-off).  This hook is on very light duty since it
only needs to support itself (insulation included) and the loose short
transposing line and not the tower-to-tower line (hence the one-inch size).
My guess is that there was a small crack on the inside-side of C as
installed, which gradually propagated (stress-cracking, maybe) and deformed
C into L then broke.  If they had seen it from the side of the tower they
would have seen the L-shaped C-hook.  It is one of blind spots, I think, in
a sense that the part is in such a light duty that its failure is not
expected and therefore was not inspected. The transposing line is still
hanging there because the line is, as the article says, steel reinforced
aluminum (attached) and even aluminum melted, the steel core held.
Interesting arguments (forget about the "indignant-ness" of some comments.