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Old 10th Jan 2017, 22:08   #101 (permalink)
 
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Originally Posted by rrekn View Post
And HUMS close monitoring of the Tail Rotor Pitch Change Bearing is now required.

Sikorsky taking the lead from Airbus?

Anyway: Thumbs up!
That is the right approach to be rather cautious than sorry! It won't have too much impact to do these inspections and it makes sure a potentially preventable accident does not occur. That is exactly the pro- active approaching of a known issue that Airbus/EC should have done after the first occurance of each - the Rotor separation and the bevel gear shaft. Would have saved a number of Lives and them an economic disaster.
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Old 11th Jan 2017, 02:12   #102 (permalink)
 
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...and to add to the SA330J story, the same inclined drive shaft cover issue as the AS332L but with less spectacular results, it only opened out to within 1" (metric) of the tail rotor in SUM. Lesson learned not adapted on subsequent variant.
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Old 11th Jan 2017, 07:19   #103 (permalink)
 
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Originally Posted by c53204 View Post
A very simplistic question from someone who has many pax hours in helicopters. Is it fair to say that mechanical failures are happening more on helicopters? If so, is this because of modern design - i.e. Lighter components to save weight/increase payload, etc, etc.

All my hours in Sea Kings, Pumas, I never remember a Main gearbox, bearing, or tail issues, ever - certainly not 'accident' or grounding issues.
Mostly the advent of social media and the 24 hours news culture that demands instant answers. The 70s, 80s and 90 are littered with serious incidents/accidents - many involving that old favourite, the S61! Some UK AAIB examples here: https://www.gov.uk/aaib-reports?keyw...rence%5Bto%5D=
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Old 11th Jan 2017, 12:19   #104 (permalink)
 
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However a number of aircraft are engaged SAR and as bulletins are not mandatory even if given Alert staus I suspect that in a real emergency they will launch. At time of writing I cannot find an Emergency AD from either the FAA or EASA which would be mandatory.
...yet the SAR aircraft were grounded (no doubt briefly) as well as the O&G ones.
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Old 11th Jan 2017, 13:04   #105 (permalink)
 
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Originally Posted by henra View Post
Anyway: Thumbs up!
That is the right approach to be rather cautious than sorry! It won't have too much impact to do these inspections and it makes sure a potentially preventable accident does not occur. That is exactly the pro- active approaching of a known issue that Airbus/EC should have done after the first occurance of each - the Rotor separation and the bevel gear shaft. Would have saved a number of Lives and them an economic disaster.

Agreed, but again we seem to be relying on HUMS as an airworthiness assurance tool, rather than the reliability tool is was designed as. If you can't say that the bearing will last for 3 hours, it shouldn't be flying.


HUMS didn't find the EC225 Epicyclic failure...
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Old 11th Jan 2017, 13:04   #106 (permalink)
 
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No doubt also using the option of a 6 hours HUMS download interval that SIK are offering...
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Old 11th Jan 2017, 14:08   #107 (permalink)
 
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Special Bulletin out from AAIB: https://assets.publishing.service.go...017_G-WNSR.pdf
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Old 11th Jan 2017, 14:29   #108 (permalink)
 
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Holy sh*t!!!!!! Boy were those guys lucky. Does their diary read: note to self, if in doubt there is no doubt - shut down and get it checked?
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Old 11th Jan 2017, 14:42   #109 (permalink)
 
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Nice to see a manufacturer dealing with an Authority in a manner that promotes transparency and safety for a change. If only it was like this all the time.
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Old 11th Jan 2017, 15:29   #110 (permalink)
 
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Interesting that HUMS showed out of limits before the flight commenced but this wasn't picked up.

Surely some kind of automatic 'red light' should pop up on the HUMS interface as opposed to relying on someone going in to check every single possible parameter for exceedances?
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Old 11th Jan 2017, 16:55   #111 (permalink)
 
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Why the delay?

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Originally Posted by 212man View Post
Howcome, with a major (potentially catastrophic) loss of control, it took more than a week for the AAIB to be informed of the incident?
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Old 11th Jan 2017, 17:14   #112 (permalink)
 
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So HUMS picked this up the night before with a 4.5hr pre warning before failure. Yet the aircraft was released to fly the next day on the 28th.

It then goes on to say that the operator has introduced an additional assurance check on the HUMS, i.e a secondary inspection of the HUMS?

So there's been a major **** up there by the operator. That reads to me that the engineer has released the aircraft to fly with a warning on the bearing. The aircraft should clearly have never departed on the morning of the 28th had the engineer who signed for the HUMS reported or troubleshooted the warning properly.

The exact same thing happened with the bevel gear, the download the flight before picked up on the crack 4-5hrs in advance but the download frequency was wrong.

I guess that is why HUMS has a 5FH limitation check imposed by the operator and now a secondary check?

HUMS has turned into an airworthiness assurance tool ever since G-REDL and then the 2 bevel incidents. You can't fly without it and in CHC's case it also mentions in that report that it must be fully serviceable before take off rather than a deferred item that years gone by you would have got away with.

Saying all that, the primary cause of this incident was a component failure so the 'blame' ultimately lies with Sikorsky. CHC however should have picked up on it the night before.

Interesting reading but it shows that Sikorsky and CHC and equally the AAIB have been pro active in addressing this issue and for that they should all be applauded. It afterall only happened less than 2wks ago and now we have a report, an emergency AD and beefed up HUMS procedures and analysis tool.

All in 2wks, Big clap.
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Old 11th Jan 2017, 17:57   #113 (permalink)
 
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The Sikorsky S-92, like its competitor the AH H225, is a good modern aircraft with a safety record well ahead of many of its predecessors. However, I do not think it is so perfect that it can sustain the pressure of being the sole or main large helicopter in O&G crew change. If it is doing most of the work then it will have most of the accidents. There needs some solution that spreads the load before that scenario plays out in the most frightening way.
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Old 11th Jan 2017, 23:56   #114 (permalink)


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So if the tail rotor pitch goes to a min-power-ish setting, what sort of run on speed does that equate to?
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Old 12th Jan 2017, 02:33   #115 (permalink)
 
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So if the tail rotor pitch goes to a min-power-ish setting, what sort of run on speed does that equate to?
That would very much depend on AUW I'd imagine
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Old 12th Jan 2017, 06:32   #116 (permalink)
 
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Originally Posted by Hueymeister View Post
So if the tail rotor pitch goes to a min-power-ish setting, what sort of run on speed does that equate to?
From memory, the BHL GoM aircraft ran on at about 80kts and the Norsk one at 55 kts.
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Old 12th Jan 2017, 07:47   #117 (permalink)
 
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Originally Posted by FleurDeLys View Post
Howcome, with a major (potentially catastrophic) loss of control, it took more than a week for the AAIB to be informed of the incident?
Agree, this should have been treated as a catastrophic loss right from the start for investigation purposes. It was only extreme luck and crew reactions that prevented loss of life.
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Old 12th Jan 2017, 11:16   #118 (permalink)
 
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A few years ago I was taken to task for suggesting a cockpit warning regarding excedances, & told that pilots would not be able to understand the data, seems the engineers have only a loose grasp as well.
As FC80 says & I suggested
Interesting that HUMS showed out of limits before the flight commenced but this wasn't picked up.
Surely some kind of automatic 'red light' should pop up on the HUMS interface as opposed to relying on someone going in to check every single possible parameter for excedances ?
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Old 12th Jan 2017, 11:22   #119 (permalink)


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Is the HUMS data not streamed live back to Ops in the case that anything untoward show up?

80kts is a quick run on!
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Old 12th Jan 2017, 11:41   #120 (permalink)
 
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500e - I actually noticed after I posted that there is a footnote in the report that basically says that there is an upgraded HUMS groundstation available that automatically flags up any problems but this version wasn't being used.

It does seem like a rather large hole in the Swiss cheese to not have had that from the beginning. I've seen some of the kind of data HUMS spits out and it's not (as far as a stupid pilot like me is concerned at least) always easy to interpret.

Huey - no, HUMS parameters are downloaded to a data card which is then removed from the A/C at the end of the flight and downloaded again onto an engineering groundstation. Live streaming would be impractical and hugely expensive right now I'd imagine.
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