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North Sea Helicopter ditching 10th May 2012

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North Sea Helicopter ditching 10th May 2012

Old 15th May 2012, 17:25
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Scots

Thanks for the response Scott - A lot of people are wondering why the gearbox on the heli in question wasnt investigated further?
We've been informed the pilot had reported some vibration anomalies on an earlier flight.

Some of us think a year is too long between inspections.

Thanks all the same.
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Old 15th May 2012, 19:21
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Engineers arent sitting around in our place while the aircraft are flying. usually one or two on maintenance of some kind while others are working the line. not much time to be watching telemetry.

Since the oil/helicopter companies dont like paying for engineers as it is im not sure whos going to stump up for the extra people to expand the hums/telemetry dept.

shame though because its great those examples of detroit diesel and Caterpillar and also some luxury car makers do that too.
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Old 15th May 2012, 19:31
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Angel EC225 ditching May 2012

Yeh! there is a separate tank outside the MGB which contains Glycol, in the event of a main and emergency pump failure, the glycol or emergency lub system is selected which will lub the gearbox and hopefully get you back safely, think in this instance the oil and the glycol was coming out of the gearbox, and eventually the emergency lub system failed too, giving them no option but to ditch.
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Old 15th May 2012, 21:07
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TrisG

Be assured, the gearbox, like the whole helicopter, is inspected at one level or another, daily. In fact, if you count the HUMS too, almost constantly.

I know there is a lot of discussion going on about how effective HUMS is, and clearly (like everything) the technology still evolves, but in truth itís a powerful tool which helps engineers monitor the condition of critical components on an ongoing basis and helicopter flight is safer for it.

Next time you land, perhaps ask your helicopter company if they could offer you a few minutes to show you around engineering and tell you how the maintenance plans work. Youíll be comforted, whoever you are flying with.
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Old 15th May 2012, 21:17
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And well done to the crew for compliantly following the flight manual.
Next time, won't you please wipe the drips of sarcasm before you hit the "submit reply" button? You got my screen all wet.
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Old 15th May 2012, 23:12
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Tris:

Curious to know who "we", are? And by whom were you all informed (RE: the pilot reporting vibration anomalies)?
Sounds like a juicy bit of gossip there.
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Old 16th May 2012, 00:14
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wire less

The Eurocopter 225 Glycol system is a loss system. It is only designed to work for 30 minutes at Vy (approximately 70-80 knots) which equates to the minimum horsepower going through the MGB. It did not fail, it did its job and allowed G-REDW go get closer to land. It undoubtedly contributed to the successful ditching.
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Old 16th May 2012, 01:36
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Originally Posted by industry insider View Post
wire less

The Eurocopter 225 Glycol system is a loss system. It is only designed to work for 30 minutes at Vy (approximately 70-80 knots) which equates to the minimum horsepower going through the MGB. It did not fail, it did its job and allowed G-REDW go get closer to land. It undoubtedly contributed to the successful ditching.
This is not correct.

From the AAIB SB S2/2012:

The crew of the helicopter carried out a controlled ditching following indications of a failure of the main gearbox (MGB) lubrication system and, subsequently, a warning indicating failure of the emergency lubrication system.
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Old 16th May 2012, 01:57
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Be careful with SM, he is not S
I presume the "S" refers to "smart". It's something I think most, if not all, here would agree upon.
And well done to the crew for compliantly following the flight manual
It's a book of suggestions, not to be slavishly followed in all cases, which is where an aviators experience comes to the fore. Slavishly following manuals, SOPs etc have been the cause of past accidents. Being management with your head stuck where the sun don't shine you wouldn't be aware of that.
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Old 16th May 2012, 01:58
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Heli

One only needs to read the GE AAD summary reports to know that it is only a minor improvement and others need to realize it is not capable of real time results.

As to pilot alerts the reg agencies forbid it for very good reasons.

TC
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Old 16th May 2012, 02:17
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B73....read the statement very carefully....it said "indications of a failure" which does not mean the system actually failed.

My impression upon reading the AAIB report was the Glycol system worked...but Cockpit indications were it had failed. HC and others discussed the fallibility of the sensors associated with the glycol system and noted their TBO was halved after routine Engineering protocols determined the problems with them indicating properly.

I am sure HC shall set me straight if I am off in this.
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Old 16th May 2012, 08:33
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I think the emergency lube becomes slightly irrevelant when you have an unsupported shaft loose in the gearbox. Metal was being made hence the chip caption. The only option here is to do what the Captain did. Emergency lube is for loss of oil, not for a catastrophic failure of a gearbox component. EC obviously thought that this would never happen otherwise you wouldn't put both pumps on the same shaft.
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Old 16th May 2012, 08:50
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Nicely said Cyclic, that's the most sensible post I've read for a while...
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Old 16th May 2012, 09:18
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teej5536

I work offshore. The "we" you refer to are the people who were present at the OIM's brief.
He was relaying information given to him directly from Bond via the operating company.
The chopper in question landed offshore (at our installation) on an earlier flight and reported some high vibration levels which were subsuquently relayed to the beach and the crew were informed they were within operating limits and it was safe to continue.

Thats all I know.
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Old 16th May 2012, 10:14
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It amazes me how the shaft managed to break. Gearbox oil pressure, main and standbye, is not very high and I would not have thought that it would put any undue torque on the driveshaft. The early Pumas did not even bother with a pressure guage; they just had a light on the CWP. I presume they were standard gear pumps like 100,000s of car oil pumps which seem to go on for ever. I can see why EH thought it might never cause a problem.
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Old 16th May 2012, 15:57
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HUMS in real time would not be a reality, near real time maybe and segmented data maybe but not true real time. You could have the system do some alerting to notify someone at the beach/ops center of a potential issue and may be able to do some spot or threshold monitoring but currently that would be about it.

A few other issues you would have to deal with and have been raised in other discussions is how much do you want someone from outside the aircraft making choices for those in it. Not only would you have to deal with a lot of decisions on what extent you want to go per your company guidelines you may also have to deal with government/operational area rule sets as well which may limit or prohibit this activity.

Then you have to deal with equipment. On a truck or piece of shore based equipment you have an unlimited amount of flexibility as to where you can place your antenna and the gear for the system and how it's wired up. With an aircraft you just can't do that. Not only do you have to get approval to add the gear, you may not have the proper real estate on the airframe to place it.

On top of that you have to judge satellite communication reliability. I would guess that most company's don't know what that is currently but I can tell you that at times it can be spotty and most days you will have at least 2 short periods of drop out of coverage (Iridium) . They are short but they will effect any and all data. In addition you can count on it that systems will loose connectivity and need to have power recycled and you will need a way to identify that the system is not sending data or good data and have the pilot intervention to try and correct the issue.

So a but off the main focus of the thread but some things to consider when talking about real time HUMS data.
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Old 16th May 2012, 18:41
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just a small point for etouffee.

The coastguard utilise sat comms as well as some of the O&G fleet in aberdeen, so they are used.
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Old 16th May 2012, 20:57
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All the talk of real time HUMS totally depends on the system recognising that there is a problem. If the failure is a first ever, how do you know what the symptoms will be?
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Old 16th May 2012, 21:29
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If this a/c had "High Vibration" on an installation how could the beach possibly relay that it is within limits and to continue without seeing the a/c or checking the hums data ?
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Old 16th May 2012, 22:24
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Exactly, and that shows both the power and the danger of "a little knowledge" and Chinese whispers!

Or maybe they checked the pilots' teeth fillings, and finding them still intact, with headsets having not fallen off, declared the aircraft to be serviceable.

I do have some sympathy with the offshore guys - we scare them witless with the Safety videos (aka disaster movies) before each flight, and we feed them just enough information for them to be frightened. Sometimes I think it would be better if we behaved like British Airways etc and just stonewalled any requests for information following minor events such as the one cited.

HC

Last edited by HeliComparator; 16th May 2012 at 22:25.
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