Regarding HUMS I became familiar with the concept as it was built into the dynamic systems of the EH-101. The only problem I can see with it is that the vibratory temperature limits and acoustic parameters that are programmed into it are developed under controlled conditions. This black box is then installed into a helicopter that may have several thousand operating hours. If the programming does not cater to the older helicopter that may be perfectly good but it is operating at higher temps, higher vibratory levels and generating acoustic patterns that are close to the allowable limit for a new helicopter but still be perfectly acceptable for a helicopter with high hours and my assumptions are correct the HUMS system will result in a high pull rate of dynamics components that are still serviceable. But then again, what do I know?