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Old 3rd Jan 2017, 22:28   #41 (permalink)


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Following up a post by Industry Insider, can anyone explain the Sikorsky "HUMS Tail Gearbox Bearing Energy Tool"? Is it part of a routine ground station analysis? Does it gather sensor data independently of accelerometers?
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Old 4th Jan 2017, 00:15   #42 (permalink)
 
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Marv, (sorry)

It is a condition indicator looking at a spectrum of vibration at discrete frequencies or over a specific broad frequency range. As bearings fail or are loaded abnormally the discrete or broadband magnitude/energy increases. Unless the HUMS accelerometer is actually at the bearing these signs are not present and the fault is not detectable.

The Sultan

Last edited by The Sultan; 4th Jan 2017 at 04:29. Reason: Typo in name
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Old 4th Jan 2017, 00:21   #43 (permalink)
 
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Don't write-off FSTDs just yet.
They can prove very useful if given the right data.
The problem of course is finding someone with a wheelbarrow big enough to carry the Cahoonas of the pilot carrying out the test program.
The recent developments in modelling wind turbulence is a good example in improving FSTD fidelity.
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Old 4th Jan 2017, 01:04   #44 (permalink)


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Thanks Sultan, do you know if there are conventional HUMS alerts (amber and red) associated with the tail rotor pitch change shaft bearing condition indicator? i.e. a way to categorize a bearing as 'normal' or 'abnormal'?
Marv
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Old 4th Jan 2017, 06:55   #45 (permalink)
 
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So it is two questions: are all operators following the OEM recommendation to use the HUMS tailrotor gearbox bearing tool, and would live or more frequent monitoring have caught this before the excitement on the deck.

How was the aircraft recovered to shore?
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Old 4th Jan 2017, 07:32   #46 (permalink)
 
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Reply to John's last post:

John, the loss of T/R drive anecdote that I had heard did not achieve balanced or prolonged controllable flight. From recollection they had to enter a lowish power descent with right turn and I would guesstimate some degree of slip but personally uncertain.......but importantly ....it bought them time so say a few Chinese expletives (ie "ahh F..k") and to make a few decisions and pull off a relatively safe landing/termination with all on board safe as I recall...

I know...growing old ain't for the faint hearted...

Cheers
RG
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Old 4th Jan 2017, 10:26   #47 (permalink)
 
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The S92a hums system New and old does have green amber red indicators as in other systems.
It also has a "toolbox " which in the early hums you had to upload separately in the later it is done with the main download of the card.
In the tool box is specific programs which look at tail gearbox bearing energy, tail rotor dis-bond, Mgb foot skew and engine drive shafts.
These programs give you another green or red indicator to simplify and speed up hums analysis of critical previous problem areas.
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Old 4th Jan 2017, 13:31   #48 (permalink)
 
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Some pics below...

https://www.energyvoice.com/oilandga...gency-landing/

As to the HUMS, it's my understanding that it was effective in this case in regards that it picked something up but I have no confirmation on that other than hearsay from other parties.

From the pictures above, it looks like the crew done a very good job getting it on the deck.

Last edited by Mitchaa; 4th Jan 2017 at 18:39.
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Old 4th Jan 2017, 14:23   #49 (permalink)
 
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And some others





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Old 4th Jan 2017, 15:45   #50 (permalink)
 
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Quote:
Mitchaa - It is my understanding that HUMS was effective with a warning in this case
I need help with your logic...your helicopter is almost spun off a deck in a near catastrophe. Surely if the HUMS was effective in warning then the aircraft would not have made that last flight to the rig.
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Old 4th Jan 2017, 16:08   #51 (permalink)
 
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Close Calls do not count statistically.

I would say the Crew deserves a "Well Done! for getting the aircraft onto the Deck!
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Old 4th Jan 2017, 16:46   #52 (permalink)
 
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Looking at the deck there may be a hard landing check in order.
Well done that crew in anycase.
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Old 5th Jan 2017, 09:35   #53 (permalink)
 
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Quote:
Originally Posted by SASless View Post
I would say the Crew deserves a "Well Done! for getting the aircraft onto the Deck!
+1.

Plus the relatively wide track of the main gear of the S-92 probably was a good thing in this case as well. Had it fallen on its side the outcome might have been different.
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Old 5th Jan 2017, 14:13   #54 (permalink)
 
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It doesn't add much, but the AAIB says it is now sending a team to investigate. (An hour earlier, it said merely that it was looking into reports of an incident.)
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Old 5th Jan 2017, 14:36   #55 (permalink)
 
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Yes Henra the 92 is like a flat iron compared to some other helicopters.
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Old 5th Jan 2017, 15:27   #56 (permalink)
 
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Interesting to see the nosewheel at 90 - I wonder what effect it would have had if it had been lockable? Might have either resisted the rotation, or exacerbated the tendency to roll over!
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Old 5th Jan 2017, 17:16   #57 (permalink)
 
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If there was some loss of tail rotor control, would the canted tail rotor and its complex yaw/pitch coupling of control inputs have compounded attempts to control the aircraft and get it planted onto the deck? A loss of lift at the tail might explain the slice in the aluminium alloy decking, seen in 2 of the photos, roughly radial to the landing circle.

The crew did well to keep it on deck, once it had made initial contact, and not hit the nearby crane. Or worse.
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Old 5th Jan 2017, 17:16   #58 (permalink)
 
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Just speculating but are the cuts in the deck caused by the wheel rim?
If so the tires must have nearly been rolled off the rim.
Must have been an interesting few seconds.
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Old 5th Jan 2017, 17:18   #59 (permalink)
 
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Nice to see a happy ending to someone’s really really bad day.
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Old 5th Jan 2017, 17:20   #60 (permalink)
 
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They don't call them poopy suits for no good reason!
212 man: not an expert by anymeans but I suspect that the ability of the 92 nose gear to castor was beneficial, in this case, to keeping the aircraft upright. A locked nosewheel would, I think, have contributed to any rolling movement. I wonder how much the aircraft actually tilted. Thoughts?

Last edited by albatross; 5th Jan 2017 at 19:22.
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