if used properly they can give significant cost benefits (I won't bore you with how)
Well, I was hoping someone might, actually
Here's my idea:
A low-cost HUM system for an R22/R44 is technologically quite straightforward - just a DSP and a few accelerometers, with some time-frequency analysis software. Such systems are widely available for monitoring machinery.
Price ? Well I can buy an EGT/CHT monitoring system for a six-cylinder fixed wing engine for about $5000, fully approved. I reckon this is about the same level of complexity as a
simple HUM unit.
So let's say it's possible to sell an R22/R44 monitor for $10,000. Is it conceivable that maintenance savings over the life of the helicopter could pay for this ?
(To placate those who actually know about these systems - I realise that the above is highly speculative, I'm just trying to find out how many orders of magnitude I'm out by.)