In case you are wondering what AWN 19 is:
The Problem Of Bogus Parts
1 The CAA is becoming increasingly concerned about the quantity and variety of unapproved parts which are finding their way on to UK registered aircraft, in particular helicopters. Evidence indicates that these counterfeit and/ or fraudulently identified parts are being imported, largely from North America, however the CAA also has evidence of such bogus parts originating from the UK and also other foreign sources.
et etc
see
here