Originally Posted by
Mitchaa
The IMD software picked up on this with a 5hr warning.
SGBA picked up the same.
Sikorsky then run it though an enhanced algorithm and found that the 5hr pre warning above could actually be detected around 20hrs before with a tweaked algorithm.
This is the basis of the new SGBA patch and the reason why there is a 3hr limitation on flights that continue to use the IMD.
There will be a delay, engineering will need retrained on SGBA so it won't be an instant switch over for the companies that are not using it.
All operators should have their dedicated HUMS specialists, if they can't solve an issue they then go back to the Sikorsky HUMS team.
From my understanding, engineering do not like S92 HUMS as it's based on a bundled up health indicator rather than single condition indicators. The S92 HUMS system very rarely generates alerts, where the other HUMS systems may give out too many. Are the others too sensitive, and is the S92 system too dumbed down? That's the way it feels. Sikorsky only add additional toolbar algorithms post mechanical failures/issues and are not catching things before they break (for the first time)
With conventional condition indicators, SO1/SO2 etc you could work out what was wrong with a driveshaft for example, imbalanced, misaligned etc, the S92 HUMS system doesn't really react like that, it bundles all condition indicators together to create a health score and that's perhaps the reason why it may miss quite a few things.
What I find staggering is this is being going on 10yrs and Sikorsky have not redesigned the component. With EASA/CAA and now UK operators all affected, I would hope that this will be heavily scrutinised.
Sikorsky are only one more incident away from a European grounding on these if this same failure mode happens again and then Sikorsky will be in a whole heap of 'Airbus type' problems.
What I find staggering is that one of the recommendations from the BV234 accident (how long ago), that inflight warnings of imminent failure should be looked into was only implemented by AH ( or anyone)when they had their bevel shaft problems. Once the shaft was fixed out came the warning. A lot of time has passed, I think more time and resources should be spent on HUMS it should be a more mature system than it now is. If you are pushing margins in performance you should also invest in the safety infrastructure that can allow this to happen in a safe manner. Performance is what sells helicopters. Safety is what keeps the company that sold them around.