Originally Posted by CEFOSKEY
Well then why do you suppose they dont specifically and overtly state that all helicopters should be equipped with ALS in HSS-3?
If we arent performing those analyses you posit are being omitted, then I work with quite a few people who are being severely overpaid.
Besides, the exact same sentiment could be made for the 332/225, as I do believe the Bond helo lost the entire rotorhead in flight due to catastrophic failure of the MRGB. Not to mention the EH101 and its 5+ year mystery tail rotor hub cracking issues.
Bottom line is that these are complicated machines. FMEA+FEA isnt perfect and unexpected failures happen to all makes and models. In the end these are all very safe helicopters. But alas, you troll away.
I'd agree that FEA may not be perfect, but it can be very good. Like many other things, the precision and accuracy of FEA results can vary widely depending upon the quality of the FEM and the guy that created it. FEA results also must be interpreted carefully. FEA is a well understood and accepted process in the aircraft world for validating structural design. Sometimes FEA is further validated by structural test, but this is becoming the exception as FEA techniques and codes improve.
As for FMEA, these techniques have been a fundamental part of aircraft systems design for decades. In fact, preparing a FMEA fault tree and CIL is one of the primary engineering tasks when designing any new system architecture (like an MRGB). Since it will provide guidance on the level of fault tolerance that each component or subsystem (like a lube circuit) must have. Preparing a FMEA/CIL is straightforward logic and is not difficult or complex. It just takes time, patience and thoroughness. As I'm sure you're aware, the real difficulty lies in producing a design that ensures adequate fault tolerance.
Thanks for linking that HSS report. I'll definitely read through it.
riff_raff