...it may be that Nr droop and/or the lack of anticipators may be involved (or contributed in some way), as mentioned by others. If so, then it will not have escaped the notice of the AAIB/RNFSAIC that these problems have been raised, time and time again after past Puma accidents but yet nothing has been done to fix the problem; maybe the Puma MLU and engine upgrade is long, long overdue?
When I first had the pleasure of flyimg the Puma in the early 90s we were taught about it's few vices including the lack of anticipators. Fortunately the OCU staff and the 33 Sqn trg regime made the need to 'anticpate' possible Nr droop during any manouvring a priority, and so we effectively did exactly what the anticpator would do - albeit via a tweak on the collective rather than directly increasing the Ng. I'm not saying I didn't ever hear the odd 'beep', but you always new it was coming 'cos you'd not anticpated quite enough.
Now, I can't recall many (any!) Puma accidents prior to 94 where this lack of anticpation was an issue - but stand to be corrected. I do know this theme has been a feature in many accidents since, so can't help conclude that it possibly points to a lack of this 'anticpator' awareness. There are many old aircraft still out there with similar issues which, if handled correctly and flown sensibly, should remain safe. I know many fixed-wing aircraft have a minimum power setting on finals so the engine(s), albeit producing a bit more residual thrust, are ready and waiting to provide power at short notice. I do hope that the level of Nr awareness including on-sqn trg is as good as it was in my day when it helped me, my crew and passngers stay safe.