Helinut - Thanks for the input, I have read the relevant parts of the manuals, spoken to a handful of operators, and generally have a positive response. Their machines are new and shiny, but most also see a nice opportunity for some interesting work with one of their trusted pilots onboard. The mounts that i've found so far are simply a replacement side step with bolts, no mod required. The hardest problem if finding the one most suited to the task, as I have a willing agreement in place for a T2+, but it does't have the door locks in place for doors open flight. Your correct there is an optional extra required for the rear door (a lock) to enable doors open flight, limited to 60kts, but 110Kts or VNE (which ever's slower) with the hinge/spoiler mod.
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I appreciate that the AS350/AS355 is more usually used for this purpose, however with the payload requirements even the N is on the limit, especially from restricted sites, at warmer temperatures, and they're not so easy to come by either. In either case finding one that ticks all the boxes is the part thats tricky, but thats why i'm working months ahead, and it's all worth investigating
The AS355N alternative will suffice but be more restrictive with regards to MTOW for helipads that aren't clear area. I'm investigating all the options at the moment in an ideal world, and then filtering to those which are feasible with whats available. Thanks for the input - it's useful to hear things that I may not have considered