BBC news today Sikorsky grounds S92 helicopters for safety checks after incident as a "precautionary measure".

Just shows how far behind the curve our news services are

I would say there is a decision process to be made. It is a given that on oil and gas these aircraft will be grounded. 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.

Depends on the maintenance statement and the AMM.

Well, considering the microscope helicopters operate under nowadays and sensationalistic headlines in some media outlets, perhaps it was a wise idea to immediately cease 92 ops until the check had been completed.
Were any aircraft turned around and RTB while enroute offshore or did they complete their trips?

I suppose some would argue the 225 is not grounded currently....despite reality.:ugh:

Stop hitting your head, it hurts. ;)

Around 100 AH225 are fliyng every day.
.

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.

JOKE. Well..for one thing...everytime we had a chip light..or a gen failure or any other minor issue it did not get immediately reported in the media as "Helicopter Emergency Landing barely misses local Orphanage, Hospital and house with cute puppy inside! 100s traumatized!" Film at 1100. END JOKE

Nowadays any issue gets reported in the media and, unfortunately "Perception is reality".

C52304, I think it´s fair to say that we are now entering a time when helicopters are going straight into civil use. Both the types you mentioned had many hours (and problems) with the military.When problems were found and corrected.

c53204, if you have never seen a problem with those older types then you have been a whole lot luckier than some of us.

Can I sit beside you next time?

I seem to remember two S61 gearboxes burning out. One on the North Sea and the other an SAR machine. Engine run down and settling onto the back of a supply boat. A calm sea state was regarded as a good 61 ditching day.

The S76 threw a blade at Aberdeen and we flew next day with tie wraps holding the blade bearings in. When the turbines started bursting a ring of armour plate was placed around them to stop them damaging the luggage.

The old Puma 330 had problems with pitch horn bearings, inclined shaft hinges and a fatal at Aberdeen where an engine run down when the other was pulled back for training.

For the inaugural flight of the 234 they placed tea and biccies for the passengers, there being a cabin attendant. At the appointed time the locker was opened and there was a sea of writhing crumbs. Again a calm sea was 234 water taxiing time to get to the Shetland basin. A 234 was also responsible for the greatest loss of life.

The 332 started going through gearboxes like a lottery winner. There must have been three in the air at the same time in the hanger. Rotor heads cracking offshore, innumerable spurious fire warnings and again an inclined shaft hinge pin coming out. It took about two years to solve all the problems.

Alan Bristow, an ex test pilot, used to create at the helicopters companies because he did not know why the users had to do all the advanced test flying for them; this covered all companies.

It happened so often in those days that it didn't make the papers.

C53204,

The types you have mentioned were no doubt during military time. As a passenger you are very much kept out of the loop of problems going on. You would never subsequently be informed not was there any intention to. It's a different game in the civilian world when someone's paying for the flying.

Morale of the story being you got away with a lot more in the military.

LZ

Anyway: Thumbs up! :ok:
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.

...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.

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=

...yet the SAR aircraft were grounded (no doubt briefly) as well as the O&G ones.

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...

No doubt also using the option of a 6 hours HUMS download interval that SIK are offering...

Special Bulletin out from AAIB: https://assets.publishing.service.go...017_G-WNSR.pdf

Holy !!!!!!!!!!! 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?

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.

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?

Why the delay?
 

Howcome, with a major (potentially catastrophic) loss of control, it took more than a week for the AAIB to be informed of the incident?

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.

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

From memory, the BHL GoM aircraft ran on at about 80kts and the Norsk one at 55 kts.

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.

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 ? :ugh::ugh:

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

80kts is a quick run on!:uhoh:

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.

Certainly in the big jet world, things have moved on a touch. Quick Access Recorders for FDM have been replaced by Wireless Ground Links (commonly known as WiGgLes) triggered by weight on wheels and/or shutdown. Anywhere with wifi internet or data SIM connectivity means a data packet is automatically transferred per sector. Granted on Rotors Running rig turnrounds that doesn't give much time, but by the time of the next landing critical info could be conveyed. All of course assuming the important "criticial event" triggers are set up and the home base station has full analytical capability. Not quite real time but better than end of working day download.

2016-24-51
 

As a PAX I'm surprised that an operator would "miss" a HUMS threshold exceedance on the TRPCS, especially in light of the previously issued AD # 2016-24-51, dated November 18, 2016.


I appreciate that the aircraft can only be designed and operated within budget constraints, but a TR failure on an approach to a helideck is not very conducive to the drivers or SLF. What price do the operators really place on safety...


The fact that this failure mode appears to have surfaced several times before, and with it being such a critical part of the machine's airworthiness, would have IMO warranted a much more higher profile and proactive maintenance and inspection regime, including HUMS threshold monitoring.


We have been relying on this type to get to work since 2006 over here in Newfoundland, we had CGR491 on March 12, 2009 which could have been avoided if the failure mode from Broome in July 2008 had been correctly diagnosed and an AD for immediate stud change out applied. I sincerely hope that lessons are learned here this time round, as somebody earlier had said this was a large hole in the Swiss cheese.

Even with the minimum ply tyres that helicopters are equipped with 80 knots touchdown is peanuts as far as the undercarriage is concerned.

What value is data when ignored?
 

As mentioned earlier two bad events occurred post detection by HUMS equipped aircraft, yet each aircraft was signed off as "Serviceable".

As a perfect helicopter is impossible to design,build, and maintain...there needs to be a detection system to assist in ensuring faults being found and reported ergo HUMS being invented and incorporated into modern Helicopters.

What good is HUMS if its successful detection of a problem is not properly used in a timely fashion?

Half assed measures undo every Safety Program.

HUMS alone is not the last word on the airworthiness of an aircraft but it sure goes a long way in making such a determination.

Why can HUMS not be modified to provide a Cockpit warning of some kind should a fault situation be detected?

Why can the ground station not be modified so that n immediate fault message not be provided in real time to Engineering?

If airlines can live stream engineering data the it would seem the helicopter industry could do the same in specialized operations such as the North Sea and Gulf of Mexico?

Yes....that costs money....probably a lot of money....but at what point does those costs are offset by preventing aircraft losses that kill a dozen or more people per event?

SASless: are you familiar with the opposite problems in HUMS, false positives? My experience (about 2 decades ago) with a much older version of a system like the HUMS was plagued by that. I am not sure what the current state of play is with HUMS and various similar systems, but let's not pretend that it offers omniscience.

Look at the human factor here: if a given HUMS type of system is low confidence as perceived by the people using it, then there is ample opportunity for their frustration with such a system to believe that yet another false positive has confronted them.


Not saying that this is the case regarding this incident, nor the previous loss in Norway, but it's a human factor that should not be swept under the rug.

Non-Driver - for the sake of argument, what you're suggesting re. downloading via WiFi/4G every time the aircraft touches down at home base wouldn't offer any improvement on the current frequency of HUMS checking - I believe every operator in the NS now dowloads the data before every flight - including rotors running turnarounds. :)

Beat me to it! As an aside, was it not the in-flight transmission of eng data which gave clues as to which way MH370 went after all other contact was lost?

No room left under the rug with this one since the same thing happened with the pilots and the aircraft behaviour. They were presented with what we now know was evidence of impending failure but in the circumstances they were able to assure themselves that the effect was typical of local air conditions.