The only FAA AD on this part is
this one here.
It would indeed be interesting to understand the basis of this life reduction. Do you have any links to the CAA or EASA rule and AD?
What is the Enstrom position on this?
Alternately, I guess that you will be like everyone else in Europe and put your machine on the N register and tell them to go
themselves.
Part 2 - edit following a bit more reading.
The CAA issued an AD concerning this part in August 2003,
http://www.caa.co.uk/docs/536/G-2003-0002.pdf, so maybe complaining about it years after the event is a little belated?
What is the background to this life limit reduction and determination? Have you spoken to the CAA Engineer named in the AD? It certainly seems a little strange to make a determination of this magnitude, considering this model is manufactured and conformed to FAR 27, although it was originally designed to Part 6 of the CAR. Interesting issue, maybe someone has more insight?