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North Sea heli ditching: Oct 2012

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North Sea heli ditching: Oct 2012

Old 26th Oct 2012, 18:08
  #201 (permalink)  
 
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(The EC225 is, in essence, an AS332 L3).
Sadly, that's not quite true - it was officially the MK 2+. The Mk3 was scrapped but - had it come to fruition - would have been a superb piece of kit. S92 sized cabin (more or less) with EC225 dynamics and MMI!

Last edited by 212man; 26th Oct 2012 at 18:08.
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Old 26th Oct 2012, 18:10
  #202 (permalink)  
 
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I agree with HC (where's graviman when you need him!)
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Old 26th Oct 2012, 18:28
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Don't see it mentioned, but there is an acknowledged 'Shaft 3' currently being tested in France. I don't know if it was in development before REDW but it certainly has been manufactured with that accident in mind. I guess they will have to add in data from CHCN to ensure that it still makes the grade.

No idea how much testing such a critical part will have to undergo before approval.
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Old 26th Oct 2012, 19:01
  #204 (permalink)  
 
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Where the fracture occurs the shaft is not under a huge amount of loading. As HC states it's just driving two well lubricated (by the gearbox oil) gerotor pumps. Perhaps the problem is bending?

Also if this shaft was developed solely for the 225, does the other change from the rest of the 332 family - the lift housing - have an influence?
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Old 26th Oct 2012, 22:42
  #205 (permalink)  
 
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Those that have read the EASA paperwork will no doubt have picked up on the fact that it mentioned that the failure was not necessarily due to either the amount of torque applied or the number of hours accumulated...

...therefore why does the L2 have 4 1/2 hrs compared to the 3 hrs for the 225 with the 5101 shaft?

Is it reasonable to assume that the overall load through the 225 gearbox and different harmonics (5 blade head etc) produce a different type of fatigue/vibration pattern and therefore a greater chance of failure?
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Old 26th Oct 2012, 23:51
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It would certainly be interesting to know what the best guess was of the failure mode.
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Old 27th Oct 2012, 06:19
  #207 (permalink)  
 
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Is it reasonable to assume that the overall load through the 225 gearbox and different harmonics (5 blade head etc) produce a different type of fatigue/vibration pattern and therefore a greater chance of failure?

It doesn't alter the fact that this aircraft has flown for 7/8 years, nearly 100,000 fleet hours, without a single aircraft induced accident, and then suddenly 2 in 5 months - With the same cause.

Something must have changed??
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Old 27th Oct 2012, 07:39
  #208 (permalink)  
 
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144 million shaft cycles per 1000 op hours? How many hours on RW & CN?
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Old 27th Oct 2012, 07:39
  #209 (permalink)  
 
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The fatal accident to G-XCEL AS 355F (3 killed) might be of interest from a technical point of view, AAIB report available on line.

The cause was put down to a batch of free wheel rollers that had a manufacturing change applied.

Manufacturers are changing process all the time so what works today might not work tomorrow.

As has been pointed out the 225 has flown thousands of hours without incidents of this nature till recently so a change is a likely cause.

This failure doesnt affect the fundamental safety of the design but has to be addressed urgently..

Have a read at the report above it offers some insight in to this isssue.

Two engineers and the pilot were killed in the 355 on airtest. One of the engineers was a good friend the second the son of another well known engineer. Very sad indeed.
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Old 29th Oct 2012, 11:50
  #210 (permalink)  
 
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I see Talisman have started to use a boat to 'crew change'.

How long until other companies do the same?

Cant be good for CHC/Bristow/Bond???

Last edited by helicrazi; 29th Oct 2012 at 11:52.
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Old 29th Oct 2012, 12:46
  #211 (permalink)  
 
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I don't think crew-change by boat is going to be bad news for the helicopter companies. The limitations in terms of sea state (for basket transfer or similar) are very restrictive and that coupled with a 10h+ journey to and from the rig is not going to be a sustainable long term solution. However I'm sure it will provide welcome relief in the short term (at least for workers stuck offshore).

The real question is going to be over who picks up that tab for consequential losses due to the unavailability of the aircraft? My guess is that Eurocopter will have some liability however I can't see them paying for lost revenues because oil companies can't get their staff to and from the rigs ...
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Old 29th Oct 2012, 13:45
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Most helicopter contracts do not have a consequential loss clause so the oil companies will be responsible for their own losses resulting from this.

A bigger problem is that many contracts have the oil company paying during temporary groundings. The question will be how long is temporary, and at what point will force majeur be declared? That could mean that Bristow / Bond / CHC don't get paid during the period of force majeur. But their respective financiers will still want to be paid.

Even if force majeur is not declared, the clock to release contract aircraft or even terminate the contracts has started ticking. The fact is that most contracts can be suspended for much lower rates within 15 - 30 days and terminated within 30 - 60 days. If this is not fixed to allow some flying with restrictions within the next 7 days, it could start to impact operators and their staff.
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Old 29th Oct 2012, 14:21
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Just to make things clear. the Talisman boat transfer for offshore workers does not involve basket transfers to and from the platforms - the vessel is taking personnel out to the Auk/Fulmar/Clyde area and the transfers are being done from the vessel to the rigs by helicopter.
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Old 29th Oct 2012, 18:58
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CAA website has just issued a second version of their Operational Directive. Not yet looked in detail but it seems to be a minor change of words: the ban on hostile terrain flights is still in place for affected aircraft.
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Old 30th Oct 2012, 16:53
  #215 (permalink)  
 
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It seems like pretty much most offshore operators out there have grounded their 225/L2 fleets, at least in the UK, Brazil, Angola... are there any 225 flying for revenue offshore at the moment?
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Old 30th Oct 2012, 17:15
  #216 (permalink)  
 
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North Sea heli ditching: Oct 2012

How close is a Cougar to the 225/L2? Are they affected as well?
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Old 30th Oct 2012, 18:39
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All 225 in Malaysia are grounded as well.
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Old 30th Oct 2012, 20:25
  #218 (permalink)  
 
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Parallel to the S-92 Cougar crash

FH1100 Pilot prophetically wrote on 26th November 2011 concerning the S-92 Cougar crash:

"Well of course the S-92's airworthiness certificate should have been revoked following the Cougar crash! Of course. That's not even in question anymore.

SAC managed to convince the FAA guy (whose name we don't need to mention because everyone already knows who signed-off on it) that the ONLY possible source of a leak of transmission oil would be the lines leading to the oil cooler. Filter won't/can't leak...driveshaft inputs can't leak...the mast seal can't leak...the list goes on!

And the (unnamed) FAA guy said, "Yup, I agree!" But if they were using the S-92 design to justify that "extremely remote" crap, they had no historical base to draw from. If they (SAC) were using an industry-wide base for loss of transmission oil, they STILL were not on solid ground, because such things happen more than extremely remotely. (Admittedly they don't happen often, but "extremely remote" is a defined term.) SAC took the awkward wording of section 29.927(c)(1) and used it to their financial advantage.

So no, the S-92 does not IN FACT meet the requirements of FAR part-29 when it comes to the transmission. I would venture to say that there is no helicopter in existence that would qualify under that "extremely remote" clause. Why do we care? Because when you design an aircraft that's going to take LOTS of people out over some very inhospitable parts of the earth, then you are - and should be - held to a higher standard.

We know now that the S-92 transmission cannot withstand a complete loss of oil. Sikorsky admitted that their testing showed (and Cougar proved in the field) that you get "about" ten minutes of run time with no oil. This is undisputed. What's truly disturbing to me is that so few people seem to care. Pilots in particular are so very cavalier about this, as if it's a trivial or inconsequential point. It boggles my already-feeble mind.

What it boils down to is that it would have been economically unfeasible, unrealistic and unreasonable to summarily ground the S-92 fleet and force Sikorsky to redesign the transmission. Passenger safety takes a back seat to money. It's not the first time this has happened in aviation. Shamefully, it probably won't be the last. Personally, I think we owe the paying passengers - and the pilots who fly them! - more than that...better than that.

I mean, why have rules at all if exemptions and "work-arounds" are allowed and applied so freely?"

Are we facing a similar situation with Eurocopter and its EC225 this time?
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Old 30th Oct 2012, 20:43
  #219 (permalink)  
 
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Are we facing a similar situation with Eurocopter and its EC225 this time?
Yes we sure are!
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Old 31st Oct 2012, 00:35
  #220 (permalink)  
 
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To some extent yes, but there are differences. The S92 blatantly does not meet the certification criteria, but as you said, it was too commercially and politically difficult to withdraw the certification. A technical fix is probably n the way but these things take a long time.

Of course one of the reasons it takes a long time, is the time to get certification. So we have the ludicrous situation that the certification system that rolled over to allow the 92 to achieve certification when in most people's opinion it was not compliant, is the very same system that delays fixing the problem. It would be funny if not so depressingly serious!

From the UK CAA perspective, the accident that killed a number of people was not in their back yard so had less impact on any possible decision to ground the heli.

The EC 225 does meet the certification criteria, but there is clearly a design or manufacturing issue with a single component that has caused 2 ditchings in the UK CAA's back yard. That issue needs to be fixed, and then the heli will resume flights and be fully compliant with the spirit and letter of the certification rules.
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