The subject is a nest of vipers. How many Chinook STFs, SEMs etc were fitted in accordance with the equipment's compass-safe distance specification? In 1994 it had been 2 years since funding was chopped for the routine upkeep of these specs. By 1996 there was no requirement to even consider them in the design, although some of us kept personal copies.
Walter, you have a copy of the CPLS Service Deviation for Mk2 and it tells you precisely where the RDU is. For those too young to remember (!), MoD finally released this SD under FoI in 2010; probably inadvertently, as it had been deleted from every other copy of the RTS provided.