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S92 "unexpected control responses"

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S92 "unexpected control responses"

Old 14th Jan 2017, 10:50
  #141 (permalink)  
 
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Originally Posted by LAXX5 View Post
11 bearings have been removed however none showing any distress like incident bearing.
According to Oil & Gas People 4 TRPCS bearings have failed inspection and have been returned to the manufacturer for evaluation. 3 were from Babcock S92s, 1 more from CHC.
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Old 14th Jan 2017, 15:38
  #142 (permalink)  
 
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Originally Posted by FC80 View Post
Non-Driver - for the sake of argument, what you're suggesting re. downloading via WiFi/4G every time the aircraft touches down at home base wouldn't offer any improvement on the current frequency of HUMS checking - I believe every operator in the NS now dowloads the data before every flight - including rotors running turnarounds.
By Homebase I meant the HUMS analysis team / equipment (usually at the operator's home base) not that the data only gets sent when the aircraft is at that location. Its sent after every sector ie landing.
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Old 14th Jan 2017, 15:55
  #143 (permalink)  
 
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FAA EAD out now, some differences to ASB: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/a8ca3cce933e47bc862580a7007958f5/$FILE/2017-02-51_Emergency.pdf
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Old 14th Jan 2017, 17:57
  #144 (permalink)  
 
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This is far too long a story.


2007

http://www.pprune.org/rotorheads/163...ml#post3422865

http://rgl.faa.gov/Regulatory_and_Gu...2007-17-05.pdf
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Old 14th Jan 2017, 18:19
  #145 (permalink)  
 
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Hi All, I have only just signed up to this elite group of birdmen. Can anyone tell me if Wayne Sibley is still around? We trained together at Jayrow Helicopters, Moorabbin in 1969, converting from f/w to r/w. He went to South Australian Helicopters in SA and then to UK with Bristow. I went to Woomera SA for 6 years then back to airline flying for 20 odd years in the UK. Would love to make contact with him.
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Old 14th Jan 2017, 20:53
  #146 (permalink)  
 
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According to Oil & Gas People 4 TRPCS bearings have failed inspection and have been returned to the manufacturer for evaluation. 3 were from
At least 11(may be more by now) have been removed. 7 were picked up by HUMS and 4 by the visual inspections.
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Old 16th Jan 2017, 09:53
  #147 (permalink)  
 
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Quite a good letter from John Thorogood in the P&J this morning. He makes a very valid point about the seemingly amazing failure to use HUMS properly - again!

I wonder what is behind it. Without knowing any detail my suspicion is the usual one of the "old guard" in engineering, who fully understood how to be good engineers and the importance of HUMS, booted out / retired / retired early due to getting burnt out, and replaced with cheaper inexperienced newbies who don't have quite the same ethos or ability to stand up to ignorant management. Speculation, I'll admit. But...
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Old 16th Jan 2017, 11:59
  #148 (permalink)  
 
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Dr Thorogood is a highly qualified and experienced drilling guy who has spent decades in senior engineering positions with a household-name oil company in various corners of the world. (Probably flown in more types than most folk on here.)

His analysis is suggesting that the safety approach that prevents a UK or Norwegian offshore worker cutting their finger or tripping over a cable has not yet reached the aviation industry that flies them out there.

I can see where he's coming from.
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Old 16th Jan 2017, 16:07
  #149 (permalink)  
 
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Seems there is now a 10 hour repetitive inspection of the tr bearings.
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Old 16th Jan 2017, 16:22
  #150 (permalink)  
 
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[QUOTE]11 bearings have been removed however none showing any distress like incident bearing.[QUOTE]

This alone proves the HUMS as implemented can not be relied on to reliably catch this fault for whatever reason and necessitates changes which hopefully are coming. With HUMS I worked on with optimal sensor locations, working diagnostics, and unambiguous quick glance maintainer alert it was common to detect the earliest indication of bearing degradation. This detection was well before (weeks/months) before a safety issue might occur. While still serviceable bearings might have been pulled, all pulled bearings showed early signs of degradation. Also no bearings that would have been considered acceptable for reinstalling were removed for false alarms.

The fact that so many distressed bearings had been found only after the fact calls into question not only the aforementioned maintainer alerts, but also whether or not the current sensor used is adequate for the task.

The Sultan
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Old 16th Jan 2017, 16:35
  #151 (permalink)  
 
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Or perhaps it demonstrates that the various maintenance departments are being very cautious. An approach that I would applaud.

Only Sikorsky can determine if these bearings are indeed serviceable and also look at the HUMS traces prior to removal. This would be the only way to determine if the current HUMS tool is fit for purpose.

Sultan - you are jumping to conclusions IMHO. However given your previous posts and the obvious bias you constantly demonstrate, perhaps I am wasting my time even responding to your latest offering?
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Old 16th Jan 2017, 16:36
  #152 (permalink)  
 
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Originally Posted by HeliComparator View Post
Seems there is now a 10 hour repetitive inspection of the tr bearings.

That's where the recent FAA AD seems to differ from the previous documents stretching back to 2007.

Would it be reasonable to expect a design change of some sort shortly, whether it's bearing or HUMS or both?
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Old 16th Jan 2017, 16:42
  #153 (permalink)  
 
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Just an aside.
I have always wondered why, in some instances, a part that has worked well for years, suddenly does not.
Change in supplier, overhaul process ect?
I recall, for example, in the late 70s we suddenly had problems with Allison 250 engines. What had changed?
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Old 16th Jan 2017, 16:57
  #154 (permalink)  
 
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The FAA AD #: 2007-17-05 shows that this is not entirely new.

Whatever history there is still needs careful attention. I am reminded of a story that circulated in defence quality assurance circles in the 1980s. Whether it is true or folk-legend BS I do not know. A new aircraft type suffered bearing failures. One of the factors that may have seemed completely irrelevant at first was that the government, MoD, makers and the press had all been making a fuss about how wonderful this aircraft was. It turned out that the guy with the grease gun had been listening to this and because it was such a great aircraft and he was really excited to be working on it, it got an extra squirt of grease just to make sure. Oops.
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Old 16th Jan 2017, 17:05
  #155 (permalink)  
 
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Without knowing any detail my suspicion is the usual one of the "old guard" in engineering, who fully understood how to be good engineers and the importance of HUMS, booted out / retired / retired early due to getting burnt out, and replaced with cheaper inexperienced newbies who don't have quite the same ethos or ability to stand up to ignorant management. Speculation, I'll admit. But...


Probably not so far off base as One might think.

Washing out experience is a pitfall of modern management practices sometimes.

For sure what does happen is a "loss of corporate history" when long serving skilled and experienced Staff leave and the new are presented with a great opportunity to repeat history they know nothing about.
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Old 16th Jan 2017, 17:15
  #156 (permalink)  
 
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Only Sikorsky can determine if these bearings are indeed serviceable and also look at the HUMS traces prior to removal. This would be the only way to determine if the current HUMS tool is fit for purpose.
Variable

Variable,

If this is the case then the system is useless until it has an automatic at download alerting capability. Having to rely on Sikorsky for go/no go decisions after every flight is impractical when fault detection is so poor their is only a couple of hours between detection and failure as demonstrated by the current HUMS implementation in the CHC incident.

The Sultan
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Old 16th Jan 2017, 20:13
  #157 (permalink)  
 
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Sultan - Depending on the HUMS ground station being used, operators have several different options as to how they would like to handle their aircraft. Ultimately I'm sure most operators will be moving forward with the SGBA software and latest release of the TRPCS tool. This software and tool allows the operator to reset the 6 hour HUMS TRPCS review themselves rather then waiting on Sikorsky's approval.
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Old 17th Jan 2017, 13:51
  #158 (permalink)  
 
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The new Hums Bearing toolbar is Much improved and also more sensitive than previously set.
The fact that Sikorsky has produced this in days rather than months is to be applauded.
As to a cause some suspicion has been aired on the previous practice of inhibiting tail gearboxes by filing to the top with gear oil suspiciously recently withdrawn.
I wonder if the suspect shafts belong to reactivated helicopters?
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Old 17th Jan 2017, 14:04
  #159 (permalink)  
 
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Originally Posted by lowfat View Post
The new Hums Bearing toolbar is Much improved and also more sensitive than previously set.
The fact that Sikorsky has produced this in days rather than months is to be applauded.
As to a cause some suspicion has been aired on the previous practice of inhibiting tail gearboxes by filing to the top with gear oil suspiciously recently withdrawn.
I wonder if the suspect shafts belong to reactivated helicopters?
Was the oil operating/service oil?
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Old 17th Jan 2017, 15:24
  #160 (permalink)  
 
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Originally Posted by Pablo332 View Post
Was the oil operating/service oil?
According to Pitch Change shaft and Tail Gear Box records for the incident aircraft, the PCS/TGB had not been in storage and under gone the preservation procedure directing the TGB be filled to the top.
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