SD-2018/003 – Offshore Helicopter Operations – Vibration Health Monitoring (link)
The reason for the issue of this Safety Directive is because the CAA considers that it is in the interests of safe operations that UK registered helicopters conducting offshore operations in a hostile environment continue to be fitted with and operate Vibration Health Monitoring (VHM) equipment pending the full implementation of the revisions to Regulation (EU) No. 965/2012 (the Air Operations Regulation) contained within the new specific approval for offshore helicopters. This directive supersedes SD 2015/002 which is revoked.
Source: CAA.