Is this safe ? CFM 56
 

A 320 operator issued this as Temporary Revision of AFM :
LPT stage 1 blade separation : they recommend to descent in OP-DES down to 100FL , to reduce exposure to LPT stage 1 blade faiulure.
Is not time for additional checks or chenge some spare parts ?
Any comment welcome.

It sounds like an operational "work-around" pending an engineering fix.

LPT stage 1 blade separation is likely to be expensive (possible downstream damage) but not a safety issue.

Many engines have had such procedures, and were usually resolved after a permanent remedy was implemented.

When was the last time a CFM 56 threw a blade, of any description?
Answer is probably in the tens of millions of flight hours.