Our team has had 2 blocks break over the last 6 months due to corrosion inside the main supporting member just below the top.  They were being used at the time and fortunately no one was hurt.  There is no external sign of corrosion so knowing whether or not a block is damaged and will fail is not obvious.  As Meet Ref, I decided to disallow the use of the blocks for an upcoming meet and will used deck takeoffs only.  To further support this, the top of a remaining block was removed and the tube was inspected.  Corrosion was seen in this block as well.  It was decided by the assistant executive director of the Y to remove all blocks from use.   Has anybody heard of this problem happening before??  Is anyone aware of what the life expectancy for a block should be and if any routine maintenance should be performed??  These blocks are somewhat permanently installed (4 bolts) in the pool deck.  Any feedback would be appreciated!