Bristow MAYDAY off Stavanger

[M609]

Safe landing after engine issues

Dagbladet-Google translate (http://translate.google.com/translate?sl=auto&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fipad.dagbladet.no%2F2011%2F09%2F20%2Fnyheter% 2Fhelikopter%2Finnenriks%2Fredningsaksjon%2F18215423%2F)

[GoodGrief]

From a non-offshore flyer:

Do they actually try to make it home or would they also consider landing on the nearest rig/vessel?

[Fareastdriver]

Once upon a time one could, with a Puma or Super Puma, take off with offshore diversion so that if you lost an engine you would, quite safely, land offshore with one engine. Helicopter Services also did it with S61s in the 70s but after a couple of training accidents the practice was banned in Norway.

The UK oil companies cried off in the early eighties so everybody carries onshore diversion fuel. For a simple engine failure the land option is always used unless there are signs of something else going wrong; collateral damage, dirty fuel etc.

[HeliComparator]

Do they actually try to make it home or would they also consider landing on the nearest rig/vessel?

If you knew what the food offshore is like these days, you would understand why the pilots would want to return home rather than getting stuck offshore awaiting an engine! Better to die a quick death when the second engine fails than an agonising one in the toilets offshore.

HC - past my bedtime

[Fareastdriver]

I was going to say that too.

[industry insider]

Hi speed shaft problem?

[FARdude]

Shame the quality is not there!!
The S-92 involved in Tuesday’s flight turnaround is operated by Bristow Norway. The aircraft was reportedly on its way to the offshore rig Maersk Reacher with 17 people on board when, according Jackson, “a high speed shaft coupling failed,” causing automatic protective features to kick in.
One of the helicopter’s engines shut down, as designed. The aircraft is certified to operate on one engine and was able to return to base safely.:ugh:

[Horror box]

Shame the quality is not there!!
The S-92 involved in Tuesday’s flight turnaround is operated by Bristow Norway. The aircraft was reportedly on its way to the offshore rig Maersk Reacher with 17 people on board when, according Jackson, “a high speed shaft coupling failed,” causing automatic protective features to kick in.
One of the helicopter’s engines shut down, as designed. The aircraft is certified to operate on one engine and was able to return to base safely.

FARdude - welcome to PPrune and great introductory first post.

Any helicopter can suffer a high speed drive shaft failure. Many of those that have previously, have been so catastrophic that the occupants were not lucky enough to continue to land to make an uneventful single engine landing. I personally have known several people who have perished in this way in various types. Unfortunately none of these had an automatic overspeed protection system which shut the engine down safely in a split second as soon as a breakage had been sensed. The human reaction to this would be far slower and is very often far too slow to prevent the awful consequences.

I strongly suggest you wait and see exactly what the cause was before claiming quality issues. I very strongly suspect (with good reason) that the cause is not purely related to the design.

I do not quite understand your "head-butting smiley" sentiment. To my mind this is a very good endorsement of the design in that the protective systems did exactly what they should have done and made a potentially very serious, catastrophic event, into a rather undramatic engine shutdown and safe return to base. As an S92 pilot this gives me more confidence and reassures me that the overspeed protection system is a very good and robust one. The system sensed the breakage as opposed to a simple overspeed, as Np exceeded Nr and shutdown the engine before it was able to explode and destroy other components.

[The Sultan]

Sikorsky advertises their Goodrich HUMS and the Sik support center as gods gift to helicopter safety. It would appear with all the claims that this kind of failure could not progress to failure without adequate detection time. Did the box fail or the support center?

The Sultan

[oryxs]

Sultan

Having experienced one of these myself, on a Puma, it showed up on hums 12min before landing offshore and failed 10 min after t/o from the platform, in total about 35min of increased vibrations. So if there were no indication on hums during the previous flight there would be no way of knowing that it's going to fail. Hums on the s-92 will pick this up and I'm sure it would not be dispatched if it had been there.

[The Sultan]

oryxs

I agree with your statements. There are certain failures that can not be detected (planetary gears?) yet the HUMS suppliers continually over reach. Is HUMS a major safety enhancement - Yes!! However, those vendors that claim total coverage are self serving and will try to shift blame elsewhere.

The greatest "crime" related to the HUMS PR machine is the blame that went to HS on the Puma overspeed when the HUMS vendor claimed that if an accel had been fixed they would have saved the aircraft. At that time they failed to mention the 100/1+ false alarm rates which has still poisoned the waters for the benefits these systems can provide..

The Sultan

[twisted wrench]

ASB 92-63-029 released yesterday to inspect the input couplings for cracks, one time visual inspection have 10 hours or 30 days for compliance.

[Paddyviking]

S92 in question is back in service today
good work all involved :D

PV

[Aser]

Replace N.L. offshore helicopters, says union - Nfld. & Labrador - CBC News (http://www.cbc.ca/news/canada/newfoundland-labrador/story/2011/09/22/nl-norwegian-choppers-922.html)

:rolleyes:

A union representative is calling for offshore helicopters used east of St. John’s to be replaced after a reported problem with a Sikorsky helicopter in Norway earlier this week.

"Those helicopters are trouble,” said Kevin Kelly who works on the Hibernia oil platform east of St. John’s and speaks for the Communications Energy and Paperworkers Union of Canada, which represents some offshore workers.

"We all know that, right? Like one fellow said, 'What else do you do, what else do you do, right?' We're hoping these helicopters will go the way of the dodo bird."

Kelly's comments come after a Sikorsky S-92A chopper — the same model that crashed off Newfoundland in March 2009 killing 17 — was forced to return to base Tuesday after reporting engine trouble.

The Norwegian company's fleet of 11 Sikorsky S-92A choppers were briefly grounded, but have since been inspected and returned to service. The company, Bristow, said cracks were discovered in the connection between the gearbox and engine.

The Canada-Newfoundland and Labrador Offshore Petroleum Board (C-NLOPB) said Wednesday it has reviewed the incident and confirmed that the S-92A choppers transporting workers to offshore oil installations east of St. John’s have been inspected and are airworthy.

A Transportation Safety Board of Canada investigation concluded the chopper that crashed southeast of Newfoundland went down because of a catastrophic loss in oil pressure that happened after studs in aircraft's main gearbox sheared off.

[pasptoo]

Aser,

I really hope that is a wind up :ugh:

[Aser]

It wasn't a wind up, just a link related to the thread, I was surprised by the union statement, that's all. ;)

[Fareastdriver]

Be careful of the unions. They brought drove the Chinook off the British sector of the North sea.

[Horror box]

What an absolutely ridiculous statement by a so-called union official in NL. What the hell does he want, and is he really speaking for the the rest of his colleagues or is he just an uncontrolled mouth? What would he suggest they replace them with? A 225 perhaps? There just so happened to be a 225 engine failure in the same week in Norway, and have been others in the last 12 months. More than have occurred with the S92. A 139 maybe? Has he seen the various accidents around the world involving the 139? No - maybe they should do all the crew change by ship. Oh no wait a minute - Norway provides us with another obstacle there with a passenger ship that had a catastrophic engine explosion that nearly sank the ship and killed a couple of the crew.
This whole debate is moving into the realms of the ridiculous in NL I fear and all logic and perspective has been abandoned in favor of the uninformed being given audience.

[Outwest]

I personally have known several people who have perished in this way in various types. Unfortunately none of these had an automatic overspeed protection system,

That is surprising HB, are you referring to single engine a/c? Even the S61 with 1950's technology has overspeed protection. Do Puma's not have it?

[squib66]

This is the third case of sudden engine failure due to this defect AFAIK this year.

Does that not exceed the level dictated by the PC2e requirements?

[Horror box]

That is surprising HB, are you referring to single engine a/c? Even the S61 with 1950's technology has overspeed protection. Do Puma's not have it?


The most immediate that springs to mind was the HS 332 L1 LN-OPG in 1997. Cracks in the No.2 input shaft resulted in a large imbalance in the shaft, followed by catastrophic failure. The power turbines burst and cut the control rods. The aircraft had an overspeed warning and protection fitted, however it did not function correctly.
I am sure there are others here who will know more detail on that accident than I do.
There are numerous others i am aware of on different types, but most are unconfirmed due to lack of CVR/FDR.

[Outwest]

OK, HB......just wanted to clarify your statement that said:

none of these had an automatic overspeed protection system

The L1 you mention had it, but it did not function correctly.....

[Horror box]

Outwest - you are quite correct. My wording was not optimal. None of them had a system that actually shut down the engine.

[Fareastdriver]

The Puma had an agricultural system that relies on on two bobweights spinning against a spring and fuel pressure. The drive for this is from the rear of the turbine to the throttle control unit. There being no anticpator with this system some horrendous rotor droops can be attained.

However it is a saviour if the flector drive or input shaft fails because as the turbine spins up the speed monitoring shaft automaticaly slows the engine at the same rate. One case in 1979 at Teeside resulted in the pilot totally unaware that he had had a input drive shaft failure; he thought it was a simple engine rundown.

Both the 330 and the 332 used to have a system whereby No 1 engine could be disconnected from the gearbox and despite the wails from the engineers about the turbine overspeeding the engine would settle at ground idle with the Rotor Tacho showing the turbine at about 175 equivalent.

[Outwest]

Both the 330 and the 332 used to have a system whereby the engine could be disconnected from the gearbox and despite the wails from the engineers about the turbine overspeeding the engine would settle at ground idle with the Rotor Tacho showing the turbine at about 175 equivalent.

I remember way back when, we had a 212 that had a weird vibration that the engineers could not track down. One of the things they had me do was start the engines with the drive shaft removed. I was also worried that the engine would spool up very quickly and possibly overspeed.

I need not have worried, the start was completely normal, but spooky sitting in a 212 with 2 engines at 100% and the blades stopped :confused:

[oryxs]

HB

You statement regarding the HS L1 is totally incorrect. The vibration was caused by an imbalance in the shaft due to the nut connecting the shaft to the gearbox coming off. This caused the the shaft to rub against the overspeed sensors to the point where the overspeed protecting failed when the shaft eventually failed. I had one 3 years later and the system worked as advertised.

BTW good post on the NL offshore union bit. A few idiots out there making life hell for the operator and their fellow workers. Tail wagging the dog out there at present. Not a healthy working environment. Second guessing every decision made!

[Horror box]

Horror box - Cracks in the No.2 input shaft resulted in a large imbalance in the shaft, followed by catastrophic failure. The power turbines burst and cut the control rods. The aircraft had an overspeed warning and protection fitted, however it did not function correctly.

Orxys - You statement regarding the HS L1 is totally incorrect. The vibration was caused by an imbalance in the shaft due to the nut connecting the shaft to the gearbox coming off. This caused the the shaft to rub against the overspeed sensors to the point where the overspeed protecting failed when the shaft eventually failed.

Sorry I must have interpreted the Accident report incorrectly, but I did not think I was that far off. Although I will admit that my Puma tech knowledge ís a dim and distant memory now!

From the AAIB report LN-OPG (issued November 2001) AAIB/N REP : 47/2001.

the direct cause of the accident was that several fatigue cracks had occurred in a splined sleeve in the R/H shaft input of the main gearbox. This led to a lock washer getting into the power transmission shaft (Bendix shaft) of the R/H engine. This caused a large imbalance of the Bendix shaft and its subsequent failure. This gave rise to vibrations that caused malfunction of the engine's system for regulating and controlling the engine speed. As a result of this and the loss of loading due to the fracture in the Bendix shaft, the power turbine RPM rose out of control. When the number of revolutions reached approx 175%, the power turbine burst and fragments from this cut two flight control rods to the main rotor and the flight control rod for the tail rotor. It also destroyed the power turbine section on the L/H engine.