PPRuNe Forums


Rotorheads A haven for helicopter professionals to discuss the things that affect them

Reply
 
Thread Tools Search this Thread
Old 10th Mar 2017, 03:50   #1761 (permalink)
 
Join Date: Sep 2007
Location: USA
Posts: 552
Quote:
Originally Posted by 212man View Post
Epicyclic 2nd stage gear found!
Actually, that is the planet carrier. There are no planet gears present, but there is a single planet gear inner bearing race still attached at the 3 o'clock position. You can also see what remains of one of the tabs used to retain the planet gear inner bearing races at the 2 o'clock position. Took a significant amount of axial force to tear all those planet gears off the carrier pins.
riff_raff is offline   Reply With Quote
Old 10th Mar 2017, 10:57   #1762 (permalink)
 
Join Date: Jun 2016
Location: Aberdeen
Posts: 72
Quote:
Originally Posted by riff_raff View Post
Took a significant amount of axial force to tear all those planet gears off the carrier pins.
riff,

One might assume it took a similar magnitude of axial force to break 4 tabs on REDL as you can see in the photo below (Source AAIB Report 2-2011) but it is interesting that its gears stayed on and there seems to have been a limit to the axial displacement of the inner races possibly contact with the 1st stage carrier?

Of course, the axial force component on LN-OJF may well have been much, much larger than that needed to just break these tabs.

I think the major difference was in whether the larger gear fragments went outwards between planet cluster and ring gear (G-REDL) or inwards between the cluster and the sun gear (LN-OJF). All consequential to the root cause fatigue failure of a planet gear.

Attached Images
File Type: jpg Pages from 2-2011_G-REDL.jpg (141.9 KB, 138 views)

Last edited by Concentric; 10th Mar 2017 at 16:01. Reason: typo
Concentric is offline   Reply With Quote
Old 14th Mar 2017, 16:46   #1763 (permalink)
 
Join Date: Sep 2007
Location: Birmingham
Posts: 171
HC, as you predicted the next fatal incident was indeed an s92 sadly killing an Irish Coastguard crew who were only there to rescue others. At this very early stage no information is available as to what was the cause. I am sure that unless evidence of technical failure is found the S92s will keep flying. If it transpires there was a technical reason and a grounding of S92s as well as 225s is necessary it will be seriously testing for the oil and gas people. For everyone's sake let's hope they can establish the facts quickly. Another sad reminder, if it were needed, of how dangerous helicopter ops can still be.

Last edited by birmingham; 14th Mar 2017 at 17:27.
birmingham is offline   Reply With Quote
Old 15th Mar 2017, 12:10   #1764 (permalink)
 
Join Date: Aug 2004
Location: Aberdeen
Age: 60
Posts: 1,959
Quote:
Originally Posted by birmingham View Post
HC, as you predicted the next fatal incident was indeed an s92 sadly killing an Irish Coastguard crew who were only there to rescue others. At this very early stage no information is available as to what was the cause. I am sure that unless evidence of technical failure is found the S92s will keep flying. If it transpires there was a technical reason and a grounding of S92s as well as 225s is necessary it will be seriously testing for the oil and gas people. For everyone's sake let's hope they can establish the facts quickly. Another sad reminder, if it were needed, of how dangerous helicopter ops can still be.
Much as I like to score points with SAS on the S92 vs 225, I do hope this latest isn't a sudden catastrophic failure as that would seriously scupper N Sea ops. But it does show the dangers of having pretty much a one-horse town.

Obviously we have no idea yet but if it turns out to be CFIT during an instrument approach in bad weather, it does raise the question of whether one sort of fatal accident is worse than another. I'm thinking that, e.g. the Sumburgh L2 accident could have happened to both an L2 and an S92, but not to a 225. What if this accident could not feasibly have happened to a 225?

From the pilots' point of view, we hate the idea of a sudden rotor detachment as it's out of our control. Even though the probability of a CFIT is perhaps greater, we dismiss that as being something that couldn't happen to us because we are competent. And yet it still does.

From the passengers' point of view, I doubt that such a distinction is made since either scenario is out of their control.
HeliComparator is offline   Reply With Quote
Old 15th Mar 2017, 12:23   #1765 (permalink)
 
Join Date: Nov 2009
Location: Inverness-shire, Ross-shire
Posts: 1,109
Whatever the details, in the last few weeks the principle that if a type does all the work then it has all the accidents seems to be settled.
jimf671 is offline   Reply With Quote
Old 15th Mar 2017, 15:50   #1766 (permalink)
 
Join Date: Mar 2009
Location: arcachon
Age: 47
Posts: 5
SA less, one advice, do not stay at the bar before posting...
725_driver is offline   Reply With Quote
Old 19th Mar 2017, 09:22   #1767 (permalink)
 
Join Date: Oct 1999
Location: The Hague
Age: 50
Posts: 3,947
Ok, what am I missing here?
Quote:
The Safety Recommendation document relating to the accident concerning AS332L2 Super Puma, G-REDL has been updated.
(March 17th 2017)

When I look at the document: https://assets.publishing.service.go..._Header_V1.pdf

The latest comments I see are still from 2015.
212man is offline   Reply With Quote
Old 15th Apr 2017, 11:58   #1768 (permalink)
 
Join Date: Sep 2007
Location: Birmingham
Posts: 171
an update from the AIBN is due later this month I believe
birmingham is offline   Reply With Quote
Old 25th Apr 2017, 09:50   #1769 (permalink)
 
Join Date: Aug 2007
Location: Cyberspace
Posts: 89
Confirmed for this Friday:

https://www.aibn.no/About-us/News-ar...iminary-report
Non-Driver is offline   Reply With Quote
Old 25th Apr 2017, 13:10   #1770 (permalink)
 
Join Date: Sep 2007
Location: Birmingham
Posts: 171
Quote:
Originally Posted by HeliComparator View Post
Much as I like to score points with SAS on the S92 vs 225, I do hope this latest isn't a sudden catastrophic failure as that would seriously scupper N Sea ops. But it does show the dangers of having pretty much a one-horse town.

Obviously we have no idea yet but if it turns out to be CFIT during an instrument approach in bad weather, it does raise the question of whether one sort of fatal accident is worse than another. I'm thinking that, e.g. the Sumburgh L2 accident could have happened to both an L2 and an S92, but not to a 225. What if this accident could not feasibly have happened to a 225?

From the pilots' point of view, we hate the idea of a sudden rotor detachment as it's out of our control. Even though the probability of a CFIT is perhaps greater, we dismiss that as being something that couldn't happen to us because we are competent. And yet it still does.

From the passengers' point of view, I doubt that such a distinction is made since either scenario is out of their control.
From what the investigators have told us would seem some form of CFIT incident is much more likely here - no evidence so far of any technical failure
birmingham is offline   Reply With Quote
Old 25th Apr 2017, 16:49   #1771 (permalink)
 
Join Date: Sep 2004
Location: Canada
Posts: 933
Glad to hear that the new report is coming out. Hopefully it will shed some new light on this tragic event.

JOKE
Ok we need to divide our responses to the upcoming report.
Need volunteers for various groups. Tasking for each group, A to G, outlined below.
A) Reject any and all findings.
B) Correct any grammar, spelling or punctuation errors.
C) Explain why the 225 is the safest, most comfortable and longest range helicopter in the world.
D) Trash the S-92.
E) Call everyone else mouth drooling idiots.
F) Accept the report and compliment those who prepared it on their dedication and professional conduct.
G) The largest group ..to argue with groups A, B, C, D, E and F.
CLOSE JOKE
albatross is offline   Reply With Quote
Old 25th Apr 2017, 16:54   #1772 (permalink)
 
Join Date: Dec 2007
Location: UK
Posts: 129
You forgot group (H) - god complex.

Looking forward to the report, hopefully it will give more answers than questions...
helicrazi is offline   Reply With Quote
Old 25th Apr 2017, 17:10   #1773 (permalink)
 
Join Date: Sep 2004
Location: Canada
Posts: 933
Helicrazi
Rotorheads is a forum that is the epitome of politeness and rational debate when compared to some other forums.
There is one forum on PPRuNe where posting "Great sunrise today, going to be a great day for flying!" will start a fight that will go on for 20-30 pages. Friendships will be torn assunder, reputations trashed, and folks will be challenged to duel to the death.
albatross is offline   Reply With Quote
Old 26th Apr 2017, 10:20   #1774 (permalink)


Probationary PPRuNer
 
Join Date: Apr 2017
Location: aberdeen
Posts: 1
Norway crash

https://www.energyvoice.com/oilandga...-crash-report/

Super Puma ban to remain in place following latest crash report...
sinnon7 is offline   Reply With Quote
Old 26th Apr 2017, 13:55   #1775 (permalink)
 
Join Date: Sep 2007
Location: Birmingham
Posts: 171
Quote:
Originally Posted by sinnon7 View Post
https://www.energyvoice.com/oilandga...-crash-report/

Super Puma ban to remain in place following latest crash report...
As it says the AIBN is obliged to publish this report within a year of the accident.
It does seem that despite a huge effort we still only know what happened, not yet why.

“CAA UK and CAA NO continue to work closely on agreeing the next steps required to be sufficiently satisfied in order to remove our Operational Safety Directives.

Developments on the lifting and the detection capability look promising and we are hopeful that after obtaining further information we will be closer to removing our directives. At this time however the directives remain in place.

It would obviously be much easier for them if a specific reason for the failure could be established.
birmingham is offline   Reply With Quote
Old 28th Apr 2017, 11:37   #1776 (permalink)
 
Join Date: May 2016
Location: Stavanger
Posts: 9
New preliminary report out today.

https://www.aibn.no/Aviation/Investigations/16-286

"The observed failure mode in this accident, i.e. crack initiation and propagation with limited spalling, seems to differ from what was expected or foreseen during the design and certification of the main rotor gearbox. The fracture propagated in a manner which was unlikely to be detected by the maintenance procedures and the monitoring systems fitted to LN-OJF at the time of the accident."

Last edited by FNTC; 28th Apr 2017 at 11:54.
FNTC is offline   Reply With Quote
Old 28th Apr 2017, 13:52   #1777 (permalink)
 
Join Date: Sep 2007
Location: Birmingham
Posts: 171
AH has recently added a "Super Puma Information Centre" section to its website. This gives a lot more detail from them and information on the programme to return the H225 and H215 to service. This shows that out of the 341 aircraft affected 49% are now back in service whereas in O&G it is only 15%. Obviously one fact in this is location as many of those 127 are located in UK/Norway where they are formally grounded. The site show the hours being accumulated by the flying aircraft and the total hours accumulated by the types to date. It acknowledges that while they know what happened and have been able to introduce measures to mitigate the risk of a recurrence that more investigation needs to take place to understand why as FNTC noted "in a manner which was unlikely to be detected by the maintenance procedures and the monitoring systems fitted to LN-OJF at the time of the accident".

The failure mode was not what would be expected and despite a huge technical effort there is still no obvious "smoking gun". The metallurgical understanding of the events is now very thorough and it would seem that further work here offers the best chance of getting to the bottom of this one.
birmingham is offline   Reply With Quote
Old 28th Apr 2017, 14:27   #1778 (permalink)
 
Join Date: Aug 2009
Location: Texas
Age: 58
Posts: 4,755
Quote:
Originally Posted by albatross View Post
Tasking for each group, A to G, outlined below.
I think you left out the group that needs to advocate UAV/unmanned transport modes.
On a more serious note ...
Quote:
The fracture propagated in a manner which was unlikely to be detected by the maintenance procedures and the monitoring systems fitted to LN-OJF at the time of the accident."
Addressing that is critical to restoring confidence in the aircraft. If you don't get a hint/warning that 'things are going wrong in the box full of metal gears' you don't get the chance to fix, or replace, that critical component. Ouch. (Best wishes to the engineers/designers in coming up with a mode/tool/kit that can address this "graceful degradation" issue).
Lonewolf_50 is offline   Reply With Quote
Old 28th Apr 2017, 14:58   #1779 (permalink)
 
Join Date: Apr 2005
Location: OZ
Posts: 62
Quote:
Originally Posted by birmingham View Post
AH has recently added a "Super Puma Information Centre" section to its website. This gives a lot more detail from them and information on the programme to return the H225 and H215 to service. This shows that out of the 341 aircraft affected 49% are now back in service whereas in O&G it is only 15%. Obviously one fact in this is location as many of those 127 are located in UK/Norway where they are formally grounded. The site show the hours being accumulated by the flying aircraft and the total hours accumulated by the types to date. It acknowledges that while they know what happened and have been able to introduce measures to mitigate the risk of a recurrence that more investigation needs to take place to understand why as FNTC noted "in a manner which was unlikely to be detected by the maintenance procedures and the monitoring systems fitted to LN-OJF at the time of the accident".

The failure mode was not what would be expected and despite a huge technical effort there is still no obvious "smoking gun". The metallurgical understanding of the events is now very thorough and it would seem that further work here offers the best chance of getting to the bottom of this one.
My bold. I see these statements as contradictory.
If you don't know why it happened, how can you mitigate the risk of recurrence?
Twist & Shout is online now   Reply With Quote
Old 28th Apr 2017, 15:33   #1780 (permalink)
 
Join Date: Sep 2007
Location: Birmingham
Posts: 171
Quote:
Originally Posted by Twist & Shout View Post
My bold. I see these statements as contradictory.
If you don't know why it happened, how can you mitigate the risk of recurrence?
They know what happened so they can definitely mitigate the risk - one type of mgb, reduced time between inspections etc. What you cannot do is to ensure prevention of a recurrence. That can indeed only be ensured when you know why.

I agree that is the basic difficulty here and unless the reason can be established and the problem definitively resolved it will be close to impossible to get this back in the NS O&G sector. Even then the damage may already have been done.

Last edited by birmingham; 28th Apr 2017 at 15:44.
birmingham is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT. The time now is 13:49.


1996-2012 The Professional Pilots Rumour Network

SEO by vBSEO 3.6.1