Geoffers, life limited components in my experience were typically afforded the 10%, depending ... Some parts yes, some no, some with an engineering authorization. (As in actual engineers doing engineering analysis, not "engineers" as "people who repair aircraft" in Brit aviation parlance).
Getting extensions was a bit of an art, depending upon one's aircraft. With the T-700, for example, the Navy started going away from "life" removals and basically "flew to failure" of certain sub components. Brain hazy on details, but I recall the four module/section design being a nice way to make that a practical strategy.
Cheers.
HC:
Of course, however in this case it is being used to increase component lives in order to decrease costs, not to improve safety. In fact reducing safety margins. Do you understand?
I don't think you understand, yet. You are making some assertions and assumptions that I don't think you can support.
As I am not familiar enough with blueprints and particulars of each part on the EC helicopters in question, I'll not defend a particular decision. The criticisms of the maintenance on this particular aircraft loss are of interest to me. My previous point to you was not limited to this mishap. Try not to bait and switch like that, will you?
I tend to agree more with Campen, however.
The root problem however remains the shaft in question, and why it is suddenly failing on a regular basis after years of trouble free motoring. I have a feeling there is still much more to come out about that.
Remember: you can reduce cost without reducing any safety margins if your data tell you that the part remains sound. (Mind you, in service data sometimes give you the opposite result, and life/change cycles shorten, rather than lengthen).
It makes no sense to change a part that is working unless you have a good reason to believe that it will soon not work/perform as needed. The criticism in this case appears to be that there was some reason to believe a given part was in that zone. That doesn't change what HUMS can do, though as I noted above, it is hardly a silver bullet as things stand now.
The belief of the long term benefit of HUMS lives and dies on data, and on detailed anlaysis. Neither data nor analysis come free, nor quickly, nor easily.
Remainder edited, as it was pointless sniping.
