It should not matter if we are a fleet operator or an individual -of course it makes commercial sense to look after the former however it is more expensive to run an inefficient organisation than an efficient one. Eurocopter could employ a low level statistician which would give them a very clear idea of spares inventory required-they could take a higher level one and even know from where the demands would come. It is just poor management.
Sadly the directors are over paid and under whelming. The great cry that if you pay peanuts you get monkeys-in this case we have monkeys eating caviar which causes dysentery.
Let me assure you that EC are highly aware of their spares throughput. They (and other manufacturers) have this information available down to the last nut and bolt.
When I mentioned earlier that the manufacturer's highest priority is to fleet operators you have to bear in mind that even then they still don't pile-up spares on a special shelf for such customers - no, that would cost money and which, even for their "platinum" clients they are still not prepared to do. Instead they maintain dialogue with such customers (most of whom have fairly reliable utilisation patterns) and do their best to ensure that the necessary spares are available when required.
You mention poor management. The management of the manufacturers are quite capable of maintaining a sufficient spares stock and distributing it if they so wish but, it doesn't make commercial sense for them to maintain large spares stocks and for which reason they maintain their levels at a point where such items will constantly move.
Your caviar-eating monkeys are (in most cases) on remuneration packages which are performance oriented (certainly among the most senior ranks) and which effects everything. Their performance is measured through the company's share performance which is reviewed quarterly. They are not interested in longterm benefits, quite the opposite, they want continuously short-term gains which will bolster their bonuses and the bonuses to shareholders and this (in their minds) is not achieved by investing in a spares inventory which sits on shelves waiting to serve customers (as useful as that would be for their longterm customer relations).
You have to bear in mind that in many cases the manufacturers only buy in the powerplants to their products at the very final stage of assembly - for the same reason - because they don't want "unnecessary" assets sitting around any longer than is absolutely necessary. In other words, in terms of stock, the manufacturer will maintain those levels which are guaranteed to be used but will not maintain a reserve because that reserve affects their bottom-line which in turn affects the performance of the company's shares and ultimately senior management compensation. Most manufacturers will prefer to see you wait for their expensive spares (so they do not lose any short-term profit through so called "static inventory") while they order them from their suppliers or manufacture them during their next production cycle.
For small or individual operators who generally don't have the same predictable utilisation patterns as fleet operators and whose disappointment can have only limited consequences (in the eyes of the manufacturer) - then, as said earlier, you really don't stand a chance. Its a matter of pot luck really.