"Javier Henderson" wrote in message
...
May I refer you to:

http://www.kjsl.com/~javier/sb-1.pdf
http://www.kjsl.com/~javier/sb-2.pdf
http://www.kjsl.com/~javier/ad-1.pdf
http://www.kjsl.com/~javier/ad-2.pdf

That deals with the seat rails on Cessna single engine aircraft. It's
pretty straightforward, when the holes on the rails are elongated
beyond certain limits, or if cracks are observed, the rails need to be
replaced.

A crack does not make the rail unairworthy. I forget the exact wording but
it is something like if a crack goes from one hole to another then it is
unairworthy. I have had a crack in one of the copilot rails for the 6 years
I have owned the plane.