Corella Killer
Was using the standard dust-filter (particle sep.) for the engine intake. The filter came into action by a switch on the panel or in our case a button on the collective. The aircraft was in the pilot plus six pax configuration, that was about the optimum because 90% of the time we were taking pax luggage too. The dust and sand conditions were in the nature of very fine particles so that the standard filter didn't get all of it by a long way; not helped by the massive rotorwash recirculation compared to the JetRanger we were also using. Our main solution was to use pegged down shadecloth plus tyres to make a helipad for the most frequent use, to avoid the dust issue.
Have a look in the POH at the fuel filter emergency; it is quite severe and probably deserves a 'red' light rather than amber on the panel (can get Ng oscillations, limited power leading to flame-out). You could carry a spare and our mechanic showed me how to fit it in an emergency which was quite simple; at that time we were mainly worried about having to make a precautionary landing with the warning light on, and then being trapped in the middle of the bush with all the animals around, so it was an emergency get-you-home solution (rather than getting chowed!)
Our aircraft did really vibrate with just the pilot, but put 3-4 pax plus bags in there and it is 'tuned' for that typical loading, so you get a much smoother ride.
Hope this helps
Flug