What is the meaning of the term "fly back only" in AMM documents? I am reading an AMM document and I don't get the ideas below:



  Examine cracks in area A1 and A3:
  
  (a) Accept with an inspection each 100 hours, cracks on the inner or
  outer shroud if there is:
  
  A single hair line crack at the leading edge of the blade, possibly only on the coating on all blades (Area A1).
  
  (b) Accept for fly back only, cracks on the outer shrouds if they
  are:
  
  A maximum of 0.08 in. (2.03 mm) long on up to 10 blades (Area A1).


I don't get the whole idea of the sentence (a): why is that: the cracks are on the shrouds then they turn to be on the leading edge of the blade ?
And what is the meaning of the term "fly back only" in the sentence (b) ?
(a) Accept with an inspection each 100 hours, cracks on the inner or outer shroud if there is:
A single hair line crack at the leading edge of the blade, possibly only on the coating on all blades (Area A1).

The statement translated means; Allow to continue in service with 100 hour inspection cycles the following defects.

(b) Accept for fly back only, cracks on the outer shrouds if they are:
A maximum of 0.08 in. (2.03 mm) long on up to 10 blades (Area A1).

Allow for One Time Flight Only, as described in the operators Op Specs and MEL, the following defects