Fastener Installation Orientation vs. Grain Direction

[mathlete7]

Hello,
During my time at Boeing I recall that there was some issue with how a fastener was installed relative to the grain (say of a machined AL part). That is, installing a fastener in the ST vs. LT vs. L directions. I can't remember if this was a strength issue or fatigue issue. Can anyone help me out?
Thanks...

 

[TVP]

Here is one reference that explains problems with fastening into machined Al components:

http://www.robins.af.mil/shared/media/document/AFD-080110-064.pdf