A380focal - re the Pentel pen, it was on the production line and not the flight line, so temperature was not a factor. Re hydrogen embrittlement - that was thought to be the problem induced by the heat treatment process, but neither Lockheed or the supplier, Titanium Metals Corporation, were able to prove that was the case. It was eventually resolved by Lockheed replacing its acid pickling facility with one identical to that used by Titanium Metals Corp. The pickling ensured that the item was perfectly clean and prepared before use. So says a book.
