1.   And an unbalanced blade can cause damaging vibrations.

2.   Hanly apparently tossed the container into the garbage truck, whose compacting blades caused the package to burst.

3.   Problems with replacements are more often caused by blades that are not the same size as the originals.

4.   An unbalanced turbine blade can also cause such a failure, but that is usually detected during routine maintenance, Waldock said.