Bristow S92 down west of Bergen Norway

[Smokeyboy]

Latest reports 5 persons hoisted up. Unknown conditions.

Update: SAR version, 6 POB, all 6 flown to hospital. Unknown conditions.

[212man]

Latest reports 5 persons hoisted up. Unknown conditions.

Update: SAR version, 6 POB, all 6 flown to hospital. Unknown conditions.
Bristow SAR in Norway?

Very best wishes to all involved.

[Lonewolf_50]

If flown to hospital, hopefully that means still alive.

[Windblade]

Reuters - February 28, 20249:17 PM GMTHelicopter crash lands in ocean off Norway, all 6 aboard rescued(Sorry, can't post links yet :) )

[HeliComparator]

https://www.flightglobal.com/helicopters/all-occupants-rescued-after-norwegian-s-92-accident/157174.article

[OttoRotate]

https://globe.adsbexchange.com/?icao=47bfe4&lat=60.320&lon=4.794&zoom=14.0&showTrace=2024-02-28&trackLabels

Looks like a normal training run, maybe they settled into the water unintentionally?

[212man]

https://globe.adsbexchange.com/?icao=47bfe4&lat=60.320&lon=4.794&zoom=14.0&showTrace=2024-02-28&trackLabels

Looks like a normal training run, maybe they settled into the water unintentionally?
as opposed to intentionally?

[GenuineHoverBug]

Sadly, it was just confirmed that there is one fatality. The other five have varying degrees of injuries.

Update 29.2.24: One is critically injured, one has serious injuries and three have minor injuries.

[hargreaves99]

https://www.offshore-energy.biz/tragedy-strikes-during-training-exercise-as-helicopter-crash-ends-in-fatality/

[TowerDog]

Sadly, it was just confirmed that there is one fatality. The other five have varying degrees of injuries.

Update 29.2.24: One is critically injured, one has serious injuries and three have minor injuries.

The fatality was a female nurse in her 60s.

[malabo]

Same operator as the S-92 loss of control incident a week back. Coincidence or systemic shortcomings? Wonder if the crew will allow accident investigators access to CVR or FDM data on this one.

[hargreaves99]

That "loss of control incident" was 4 years ago. Feb 2020

https://www.nsia.no/Aviation/Published-reports/2024-03

[Mitchaa]

Not sure this design flaw has ever been fixed by Sikorsky other than increased monitoring -

https://skybrary.aero/accidents-and-incidents/s92-west-franklin-wellhead-platform-north-sea-2016

https://www.offshore-technology.com/features/featuregrounded-in-reality-inside-the-sikorsky-s-92-helicopter-investigation-5760853/?cf-view

I believe there were a handful of identical issues going back previously also as they issued an emergency AD just before that accident above.

https://www.ainonline.com/aviation-news/business-aviation/2016-11-28/loss-tail-rotor-authority-prompts-s-92-emergency-ad

Just a post to highlight previous loss of control events. Most likely unrelated to this event but you never know.

[albatross]

Considering the events you write of occurred in 2016 do you think your speculation is appropriate in this case?

Not sure this design flaw has ever been fixed by Sikorsky other than increased monitoring -

https://skybrary.aero/accidents-and-incidents/s92-west-franklin-wellhead-platform-north-sea-2016

https://www.offshore-technology.com/features/featuregrounded-in-reality-inside-the-sikorsky-s-92-helicopter-investigation-5760853/?cf-view

I believe there were a handful of identical issues going back previously also as they issued an emergency AD just before that accident above.

https://www.ainonline.com/aviation-news/business-aviation/2016-11-28/loss-tail-rotor-authority-prompts-s-92-emergency-ad

Just a post to highlight previous loss of control events. Most likely unrelated to this event but you never know.

[Mitchaa]

Considering the events you write of occurred in 2016 do you think your speculation is appropriate in this case?

I believe the TRPCS issue has never been redesigned so yes. They are protecting it with increased monitoring.

G-REDL happened in 2009 with Bond (16 fatal). The exact same failure mode happened again in 2016 with CHC (13 fatal)

Time apart 7yrs there. I don’t think time has any bearing on faulty design personally.

Chances of this accident being related to the same issue as the 2016 issue highlighted then it’s unlikely but they will be looking at all avenues and previous design related issues.

They likely already know the cause as they will have survivor feedback. Speculation therefore shouldn’t last too long.

[ChristopherRobin]

G-REDL happened in 2009 with Bond (16 fatal). The exact same failure mode happened again in 2016 with CHC (13 fatal)

G-REDL was a puma as was the CHC aircraft in 2016. This thread is about an S-92 🙄

[Mitchaa]

G-REDL was a puma as was the CHC aircraft in 2016. This thread is about an S-92 🙄

Thanks for that Captain obvious :rolleyes:

What does an S92 and a Super Puma have in common? What do design faults have in common? What do aviation accidents have in common?

My point was about design flaws that have a habit of coming back to bite. Time is no measure. It’s not just on Super Pumas, S92’s, it happens across the whole of aviation whether that be whirly birds or fixed wing (B737 max for example)

This thread will naturally be open to speculation until something more formal comes out. Human nature my friend.

Chill out and relax :)

[212man]

G-REDL was a puma as was the CHC aircraft in 2016. This thread is about an S-92 🙄
I think everyone knows that - Mitchaa's point was about unresolved design 'flaws'

[ChristopherRobin]

Thanks for that Captain obvious :rolleyes:

my pleasure, Captain Irrelevant

[HeliComparator]

Someone dies, this creates an opportunity for some childish bickering and point scoring. Rather sad.

[Medevac999]

Someone dies, this creates an opportunity for some childish bickering and point scoring. Rather sad.

well said!

[Jimmy.]

That "loss of control incident" was 4 years ago. Feb 2020

https://www.nsia.no/Aviation/Published-reports/2024-03


This one:
https://aerossurance.com/safety-management/night-offshore-take-off-loss-of-control-incident/

[jimf671]

That "loss of control incident" was 4 years ago. Feb 2020

https://www.nsia.no/Aviation/Published-reports/2024-03

AND ...
92-0169 was built from Day 1 as a SAR aircraft for BHL on the UK's GAP-SAR contract 2013-2017 (G-MCGC at Sumburgh). Therefore it is equipped with SAR automation.

[TiPwEiGhT]

Same operator as the S-92 loss of control incident a week back. Coincidence or systemic shortcomings? Wonder if the crew will allow accident investigators access to CVR or FDM data on this one.

The report clearly says the internal investigation didn't get access to the data.

[Blackhawk9]

The report clearly says the internal investigation didn't get access to the data.
This incident is now a fatal, so I don't think the union or anyone else can refuse access to data.

[Nubian]

This incident is now a fatal, so I don't think the union or anyone else can refuse access to data.

Which has not been the case in the first place either.

The complete quote from the section in the report:

” The internal investigation team also wanted to listen to the cockpit voice recorder in order to better understand what had happened. In accordance with internal procedures, they asked for the pilot’s consent to do so. The pilots did not consent to this, however. The content of the CVR was secured and subsequently handed over to the NSIA”

NSIA = Norwegian Safety Investigation Authority, (AAIB for Norway)

[maxwelg2]

S-92s back to regular flying over here in Newfoundland, just heard one going over the rooftop.

[albatross]

S-92s back to regular flying over here in Newfoundland, just heard one going over the rooftop.

Were they grounded?
Hope things are good in St. John’s.
I miss that place and the folks who live there.
Cheers

[maxwelg2]

Were they grounded?
Hope things are good in St. John’s.
I miss that place and the folks who live there.
Cheers

Yep, Cougar temporarily grounded the machines yesterday as a precautionary measure. Not much been mentioned to us SLF in a while about any notable aircraft type issues, some fatigue crack stuff but all seems to be captured by the AMEs. The TRPCS issue from 2016 I guess is just an ongoing HUMS monitoring point.

It will be 15 years since Cougar 491 on March 12 this year. Hard to believe how long ago that now is but never forgotten by many over here. Lest we forget…

[albatross]

Yep, Cougar temporarily grounded the machines yesterday as a precautionary measure. Not much been mentioned to us SLF in a while about any notable aircraft type issues, some fatigue crack stuff but all seems to be captured by the AMEs. The TRPCS issue from 2016 I guess is just an ongoing HUMS monitoring point.

It will be 15 years since Cougar 491 on March 12 this year. Hard to believe how long ago that now is but never forgotten by many over here. Lest we forget…

It was a sad event.This print hangs on a wall in my home ….always reminds me of 491.

https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/2000x1481/img_6194_f2d2dd5554c9a48eeca6d557649f8fe56ca76226.jpeg

[212man]

This incident is now a fatal, so I don't think the union or anyone else can refuse access to data.
I don't think it matters if it was fatal or not (in this context) - it was a fully blown accident, as described in Annex 13, so the NSIA will have an automatic right to access the CVFDR data.

[212man]

https://www.energyvoice.com/oilandgas/north-sea/549184/tributes-paid-as-norway-heli-accident-victim-named/

I see they plan to recover the aircraft over the weekend.

[jazzypjs]

No direct link to the incident but an emergency AD has been issued by the FAA outlining immediate inspection requirements for certain GE engines, including CT7-8"s
FAA AD 2014-05-51

[GenuineHoverBug]

The helicopter was recovered over night from about 2-300 m depth and has arrived at a nearby naval base for conservation and further transport to the NSIA facilities. The CVR/FDR is said to have been located.
A picture (https://www.aftenposten.no/norge/i/5BP8Qm/helikopterstyrten-utenfor-sotra-vraket-er-hevet)

[212man]

The helicopter was recovered over night from about 2-300 m depth and has arrived at a nearby naval base for conservation and further transport to the NSIA facilities. The CVR/FDR is said to have been located.
A picture (https://www.aftenposten.no/norge/i/5BP8Qm/helikopterstyrten-utenfor-sotra-vraket-er-hevet)
That is incredibly undamaged - normally the recovery itself causes some damage. It would certainly appear there was zero forward speed on impact, and little vertical. I won't speculate, but I think a picture is forming.......

[Smokeyboy]

https://www.vg.no/nyheter/innenriks/i/76E7MK/helikopter-vraket-er-hevet?utm_source=vgfront&utm_content=hovedlopet_row1_pos1&utm_term=dre-vg-76E7MK-1709374087%3Adre-65e2fa87453ecd7423a462af&utm_medium=dre-65e2fa87453ecd7423a462af

[hargreaves99]

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/900x439/a_39d6dd139e4beff5e36901df0cb68393ee178c31.jpg


https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/900x450/c_7f3160b7aacce66f500a568f0bb531d90baa5832.jpg


https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/900x543/b_03b04716b27bb3ce471d692095459137bb9c9f17.jpg

[helicrazi]

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/900x439/a_39d6dd139e4beff5e36901df0cb68393ee178c31.jpg


https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/900x450/c_7f3160b7aacce66f500a568f0bb531d90baa5832.jpg


https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/900x543/b_03b04716b27bb3ce471d692095459137bb9c9f17.jpg


Looks like no main gear and a strike to the tail.

[GenuineHoverBug]

Link (https://www.nsia.no/Aviation/Investigations/24-203) to the NSIA official preliminary information and a few more pictures. (Also in english)

[rrekn]

Also interesting that the floats didn't deploy...

[maxwelg2]

Why was the EGPWS/FLIR blurred out in the photos, were they possibly testing a new variant?

[albatross]

Also interesting that the floats didn't deploy...
Gear down, Sliding door closed, no float deployment, pilots window and 2 emergency exits jettisoned on the port side, only the aft emerg. exit jettisoned on the starboard. Interesting indeed.

Sad that there was a tragic loss of life. RIP

[212man]

Why was the EGPWS/FLIR blurred out in the photos, were they possibly testing a new variant?
Nothing to do with EGPWS (that’s GPS and radar-altimeter based) but an interesting observation about the FLIR!

[212man]

Gear down, Sliding door closed, no float deployment, pilots window and 2 emergency exits jettisoned on the port side, only the aft emerg. exit jettisoned on the starboard. Interesting indeed.

Sad that there was a tragic loss of life. RIP
Starboard door exit also jettisoned I think.

[Blackhawk9]

Why was the EGPWS/FLIR blurred out in the photos, were they possibly testing a new variant?
FLIR is ITAR, blocking it out just keeps various organisation in the US happy .

[212man]

FLIR is ITAR, blocking it out just keeps various organisation in the US happy .
I was going to suggest that might be a reason, but there are so many photos in the public domain (including the LM website) that I discounted it!

[212man]

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/477x583/img_1794_f68fadd7c7142ebb5eb6131b1d1589f355daf25a.jpeg
It looks to me like the silhouette of the landing gear is visible, top left, so maybe it came off in recovery?

[helicrazi]

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/477x583/img_1794_f68fadd7c7142ebb5eb6131b1d1589f355daf25a.jpeg
It looks to me like the silhouette of the landing gear is visible, top left, so maybe it came off in recovery?

Good obs!

[OnePerRev]

Zoom in and see those tail blades have some big lengthwise cracks in them. They were probably spinning hard to do that damage.

[212man]

Good obs!
I could not equate/reconcile the lack of damage to the airframe, with anything that would rip the gear off on impact, plus I could not see how the nose gear could be extended in isolation. Seems more plausible it was recovery damage - but pure speculation on my part.

[albatross]

Starboard door exit also jettisoned I think.
It appears so.
In any case … No matter the cause.. I think. a big …”Thank. Gawd for Dunker training” is probably in order.

[albatross]

I could not equate/reconcile the lack of damage to the airframe, with anything that would rip the gear off on impact, plus I could not see how the nose gear could be extended in isolation. Seems more plausible it was recovery damage - but pure speculation on my part.

Good catch …I didn’t notice that the aft gear is not down.

[NOQ]

What caused the damage in the tail area? And what could be the reason the floaters did not activate?

[albatross]

No direct link to the incident but an emergency AD has been issued by the FAA outlining immediate inspection requirements for certain GE engines, including CT7-8"s
FAA AD 2014-05-51

2014? Isn’t that the year of issue?
There is an AD 2024-05-51 issued Feb 16 2024 that concerns P+W PT6 engines.
I can not find an EAD 2014-05-51
Do you have a link?

[jazzypjs]

2014? Isn’t that the year of issue?
There is an AD 2024-05-51 issued Feb 16 2024 that concerns P+W PT6 engines.
I can not find an EAD 2014-05-51
Do you have a link?

Sorry, typo. It is US-2024-05-51 though. Won't let me post a link as I'm a new account holder, if you go to the Easa AD tool, it's the newest published AD.

[RVDT]

2014? Isn’t that the year of issue?
There is an AD 2024-05-51 issued Feb 16 2024 that concerns P+W PT6 engines.
I can not find an EAD 2014-05-51
Do you have a link?

FAA EAD #: 2024-05-51 (https://drs.faa.gov/browse/ADFREAD/doctypeDetails?modalOpened=true) EASA EAD US 2024-05-51

[60FltMech]

Reading the AD makes me wonder if I’ll see a US Army ASAM of SOF for the same issue when I get back into work this week..

FltMech

[ShyTorque]

There’s a big contrast between the major damage to the main rotor blades and little or none to the tail rotor.

[jimf671]

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/477x583/img_1794_f68fadd7c7142ebb5eb6131b1d1589f355daf25a.jpeg
It looks to me like the silhouette of the landing gear is visible, top left, so maybe it came off in recovery?
https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/900x439/a_39d6dd139e4beff5e36901df0cb68393ee178c31.jpg

Starboard undercarriage leg visible in this lift from the water. The label on the front of the leg is a positive identifier as is the upper link.

[albatross]

FAA EAD #: 2024-05-51 (https://drs.faa.gov/browse/ADFREAD/doctypeDetails?modalOpened=true) EASA EAD US 2024-05-51

Got it now.Thank you very much.
My BAD ……the P+W PT6 AD is 2024-04-51 not 05-51
Note to self “Drink Morning Coffee and allow it to take desired effect upon brain function before posting!”

[212man]

Got it now.Thank you very much.
My BAD ……the P+W PT6 AD is 2024-04-51 not 05-51
Note to self “Drink Morning Coffee and allow it to take desired effect upon brain function before posting!”
Must be getting old - pretty sure you’d have been sharper in the morning in Miri!

[NOQ]

What is that damage in the tail area and what could cause the Floaters to not work?

[helimutt]

https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/567x1227/img_9317_e4825ae27d73513f9465359b532286e4cc3ed997.png

[SASless]

Which model of float system was installed on the accident aircraft?

Must it not be activated until entry into the water but would self inflate if "Armed" by means of saltwater immersion switches?

The Cougar 91 Accident Report contains discussion re the various models of float systems and the procedures that pertain but that tragedy occurred some time ago and there might be differences today than noted in that report.

Perhaps someone familiar with the aircraft in question can address the workings of the Float System on this particular model or configuration of the accident aircraft.

[malabo]

Curious not just the workings of the float system but SOP on its use.

The 139 manufacturer SOP always got high marks from me for arming the floats whenever over water, regardless of speed. Some operators refused to follow that, arming only below a reduced speed.

ADSB looks like the power never came back in after the last level-off at 300' (coupled?)

[Igor13]

Which model of float system was installed on the accident aircraft?

Must it not be activated until entry into the water but would self inflate if "Armed" by means of saltwater immersion switches?

The Cougar 91 Accident Report contains discussion re the various models of float systems and the procedures that pertain but that tragedy occurred some time ago and there might be differences today than noted in that report.

Perhaps someone familiar with the aircraft in question can address the workings of the Float System on this particular model or configuration of the accident aircraft.


If you droop the rotor, below a threshold, during a cushioning into the water, they will not auto deploy as some power requirements are now offline. Even if armed. So either, don't droop too low, or be aware of this and smash the manual deploy button upon entry.

[That lights normal!]

Does that AD mean AW189s also need inspections before further flight?

GE CT7-2E1 engines

[albatross]

If you droop the rotor, below a threshold, during a cushioning into the water, they will not auto deploy as some power requirements are now offline. Even if armed. So either, don't droop too low, or be aware of this and smash the manual deploy button upon entry.

Float PWR is redundant and powered by both the #1 DC Primary Bus AND the Battery bus. So even if the RPM should drop so low (+- 80% Nr ) as to take the generators off line and the APU is not running. the system is still powered by the BATT BUS. The crew could also manually deploy the floats upon water contact, provided the system is armed, if they are unsure that the deployment system will function as advertised or the floats actually do not deploy automatically.

VNE floats armed is 80 Kts IAS. You get a caution light if you exceed 80 Kts with the floats armed followed by a nastygram weeks, if not months later from the FD monitors ( “You were the designated Captain and exceeded the VNE FLOATS Armed by 2 Kts! Do you care to comment????” A reply stating “ NO I do not care to comment. FYI I did, however, have the designated Co-pilot, who is a TRI, flogged upon return to base following quick Rotorhead Court Martial” worked very well. )

As regards “Different float Systems” The initial aircraft was equipped with “Sea State 5” floats which had 2 bags on the nose and one under the tail boom. later there was an upgrade to “Sea State 6” which added an additional float on each sponson. Arming and deployment SOP, Switches and manual deployment remained the same.
Looking at the photos you can see the aircraft had the “ Sea State 6” floats ( Panel aft and slightly below the panel with the word “Rescue”on the Stb. Sponson ) .

[[email protected]]

Other than a catastrophic power loss in the hover, one other possibility is an AFCS malfunction where the rad height didn't capture at the end of a TD. (or possibly finger trouble)

[ginty79]

Float PWR is redundant and powered by both the #1 DC Primary Bus AND the Battery bus. So even if the RPM should drop so low (+- 80% Nr ) as to take the generators off line and the APU is not running. the system is still powered by the BATT BUS. The crew could also manually deploy the floats upon water contact, provided the system is armed, if they are unsure that the deployment system will function as advertised or the floats actually do not deploy automatically.

VNE floats armed is 80 Kts IAS. You get a caution light if you exceed 80 Kts with the floats armed followed by a nastygram weeks, if not months later from the FD monitors ( “You were the designated Captain and exceeded the VNE FLOATS Armed by 2 Kts! Do you care to comment????” A reply stating “ NO I do not care to comment. FYI I did, however, have the designated Co-pilot, who is a TRI, flogged upon return to base following quick Rotorhead Court Martial” worked very well. )

As regards “Different float Systems” The initial aircraft was equipped with “Sea State 5” floats which had 2 bags on the nose and one under the tail boom. later there was an upgrade to “Sea State 6” which added an additional float on each sponson. Arming and deployment SOP, Switches and manual deployment remained the same.
Looking at the photos you can see the aircraft had the “ Sea State 6” floats ( Panel aft and slightly below the panel with the word “Rescue”on the Stb. Sponson ) .

Mate only manual floats work on BATT power. The immersion switches won’t work only on the BATT.

[Igor13]

Float PWR is redundant and powered by both the #1 DC Primary Bus AND the Battery bus. So even if the RPM should drop so low (+- 80% Nr ) as to take the generators off line and the APU is not running. the system is still powered by the BATT BUS. The crew could also manually deploy the floats upon water contact, provided the system is armed, if they are unsure that the deployment system will function as advertised or the floats actually do not deploy automatically.

VNE floats armed is 80 Kts IAS. You get a caution light if you exceed 80 Kts with the floats armed followed by a nastygram weeks, if not months later from the FD monitors ( “You were the designated Captain and exceeded the VNE FLOATS Armed by 2 Kts! Do you care to comment????” A reply stating “ NO I do not care to comment. FYI I did, however, have the designated Co-pilot, who is a TRI, flogged upon return to base following quick Rotorhead Court Martial” worked very well. )

As regards “Different float Systems” The initial aircraft was equipped with “Sea State 5” floats which had 2 bags on the nose and one under the tail boom. later there was an upgrade to “Sea State 6” which added an additional float on each sponson. Arming and deployment SOP, Switches and manual deployment remained the same.
Looking at the photos you can see the aircraft had the “ Sea State 6” floats ( Panel aft and slightly below the panel with the word “Rescue”on the Stb. Sponson ) .

Lots of good stuff there except I need to correct the one detail, on battery the floats do not auto deploy via immersion switches, even if armed.

Manual deployment required, which was my point.

[malabo]

...one other possibility is an AFCS malfunction where the rad height didn't capture at the end of a TD. (or possibly finger trouble)

From the ADSB it looks like altitude (rad alt) was captured, some power pulled in which sent the airspeed back to 100, then power back to slow down. What AP modes are coupled here? Who, how is the power controlled?

Reminds me of an Aberdeen 332L flying a scuddy non-precision to a beach airport that ended up in the water 10 years ago. Again curious on the training and SOP for the 92 in this situation, and if Bristow, CHC or even Cougar match up. We've spent over 20 years trying to figure out the best integration of autopilots in helicopters, it should be figured out now.

[helicrazi]

From the ADSB it looks like altitude (rad alt) was captured, some power pulled in which sent the airspeed back to 100, then power back to slow down. What AP modes are coupled here? Who, how is the power controlled?

Reminds me of an Aberdeen 332L flying a scuddy non-precision to a beach airport that ended up in the water 10 years ago. Again curious on the training and SOP for the 92 in this situation, and if Bristow, CHC or even Cougar match up. We've spent over 20 years trying to figure out the best integration of autopilots in helicopters, it should be figured out now.

Autopilot likely is figured out. Weak point is usually the human interface.

[ctscanner]

What is the normal crew complement on the S92 for this role? It is tragic that anyone lost their life but I am wondering why so many people were onboard a training flight. Previous posts and media reports say that the victim was a nurse employed by Equinor. Is it routine for SAR training flights to carry supernumeraries onboard?

[GenuineHoverBug]

There’s a big contrast between the major damage to the main rotor blades and little or none to the tail rotor.

Just about the only piece of information from the NSIA so far on what happened, is that impact damage suggests that it came down in a pitch-down attitude.
The recorder has been transported to the UK for download.

[helicrazi]

Just about the only piece of information from the NSIA so far on what happened, is that impact damage suggests that it came down in a pitch-down attitude.
The recorder has been transported to the UK for download.

Surely pitch down would damage the nose and flir mount? I see more rear damage?

[finalchecksplease]

What is the normal crew complement on the S92 for this role? It is tragic that anyone lost their life but I am wondering why so many people were onboard a training flight. Previous posts and media reports say that the victim was a nurse employed by Equinor. Is it routine for SAR training flights to carry supernumeraries onboard?

AFAIK Pilot/co-pilot/winch op/winch man/flight nurse, 6th person possibly a rear crew trainer, no doubt in due course we will find out what the role of the 6th person was.

[albatross]

Lots of good stuff there except I need to correct the one detail, on battery the floats do not auto deploy via immersion switches, even if armed.

Manual deployment required, which was my point.

I was looking at a old training manual and could not find a warning that the immersion switches are not powered when on Batt. Power only. Do you have a reference I could use? Thanks for the info.
I did find a reference that if you are on the ground, floats armed and below 80% NR you will get a “Floats” warning caption…perhaps that is a warning that the immersion switches are no longer powered.
Interpreting Wiring Diagrams are very far from any of area of my supposed expertise. How a lightbulb works is a mystery to me.

[ShyTorque]

Just about the only piece of information from the NSIA so far on what happened, is that impact damage suggests that it came down in a pitch-down attitude.
The recorder has been transported to the UK for download.

I'll be interested to learn if the tail rotor was turning at the time of impact.

[Mitchaa]

I'll be interested to learn if the tail rotor was turning at the time of impact.

I would think the rotor disc has impacted the water and thrown the blades, severing the drive to the tail rotor before aircraft turns upside down and sinks? Explains why there is no MR but still an intact TR?

[ShyTorque]

Possibly. I’m sure all will become clear in due course.

[BTC8183]

I would think the rotor disc has impacted the water and thrown the blades, severing the drive to the tail rotor before aircraft turns upside down and sinks? Explains why there is no MR but still an intact TR?

The 92 TRDS routing is pretty well enclosed within the pylons, which do appear 'unstruck' in the photo.

[HeliComparator]

Who on earth thought it was a good idea not to power the AFDS system from the battery bus? It's not as if it could take any significant power! And who on earth put up with that poor design for 20 years without making a lot of noise?

[GenuineHoverBug]

The recent press conference revealed little new information. The following was said:

-So far no technical malfunction that could explain what happened has been found.
-The CVR/FDR memory unit is being dried at the AAIB facilities and should be downloaded by this time tomorrow.

A video of the salvage operation has been added here (https://www.nsia.no/Aviation/Investigations/24-203).

[SASless]

HC,

If you read the AFCS thread that is currently going on re the SAR 92 that had a problem you will see I have raised the same concern as you re "Heading" control and why we still see Crews getting themselves into trouble due to the design, testing,certification and training.....but did so in a much more polite manner.

I agree with you in your concerns but it applies to far more issues than just battery wiring.

The "problem" is not isolated to one Make and Model of helicopter or to one Certification Authority or to just one Operator or Training organization.....it cuts across all of those sectors and organizations.

Question for you....what is your solution for the root cause of such decisions.....and who or which organization is responsible for seeing it gets solved much less prevented?

In this particular incident it was a Sikorsky designed and built machine, that was certified by the FAA and other Authorities, owned and maintained by Bristow, operating in Norwegian Airspace.

Pin the tail on the appropriate donkey for us.

You asked the question....offer us an answer.

Re the Heading thing I opined in my thinking the AFCS should default to the actual heading of the aircraft and any subsequent change should require a Pilot action.

I am sure there are some who attend here shall see it differently.

As to the Float system having redundant power which makes sense operationally.....somehow I can see a minor disaster happening during maintenance if switches get moved somehow while the Battery is still connected and all other power sources are not powering the system.

There are lots of factors that come into play when these "decisions" are made.

As the AFCS thread and this one have raised a similar concern re different systems perhaps a new thread focusing upon what appears to be genuine questions about built-in problems that stay with us as engineering and certification standards appear to fail to prevent such....might prove to be interesting.

[HeliComparator]

SAS, just sticking with he AFDS because that is pretty clear cut…

I seem to recall that when Bristow ordered the brand new AS332L in the early 80s, there were some changes to the wiring insisted on by Bristow, to move a few things from one bus to another. It is of course a trivial change in practice, slightly more complicated due to the weight of bureaucracy. In those days operators like Bristow had people in the procurement process who understood flying and flight safety.

Unfortunately these days procurement is done centrally and the people doing it probably only look at the manufacturers glossy brochures and the £ or $ signs. I suspect operators lack the competent people, or at least those competent people are not allowed to be involved in the procurement process.

From the manufacturer’s perspective, they have a problem in that they supply a product which could be used in numerous roles (unlike an airliner which just flies from one airport to another). So it can be tricky to match the delivered aircraft to the role, unless the manufacturer has in depth knowledge of the particular role.

But even so, basic FMEA would surely show that having an AFDS system that doesn’t work when generated power is lost (eg an engines off landing on water) is a bad design.

So who is at fault?
The manufacturer for not doing adequate FMEA relevant to the role
The procuring department of the operator for not doing due diligence on the detail and not utilising the expertise within their organisation
The pilots, for accepting the deficiency for decades without making a fuss.

So everyone is at fault. But one should bear in mind that just because everyone is at fault doesn’t mean that no-one is at fault!

[jimf671]

Who on earth thought it was a good idea not to power the AFDS system from the battery bus? It's not as if it could take any significant power! And who on earth put up with that poor design for 20 years without making a lot of noise?

It's a Sikorsky. Teflon helicopter company.

[albatross]

Who on earth thought it was a good idea not to power the AFDS system from the battery bus? It's not as if it could take any significant power! And who on earth put up with that poor design for 20 years without making a lot of noise?

EDITED to add this comment: ( People may. have put up with it for years and not made any noise because they were not aware that the immersion switches are not redundantly powered if the Gens go offline due to low NR and the APU is not on. A condition that would require manual float deployment by the crew upon water contact.) END EDIT

Well, i sure wish that someone would confirm and post a reference that the immersion switches are indeed not going work in the case that the Nr goes so low,( +- <80%, ) that the Generators fall off line and the APU is not on and working. If such is the case float deployment would require that one of the crew push the manual deployment switch on the collective. Also that would be a factor if the engines were off or at idle and not driving the rotor system at the time of impact. I can’t find any definitive warning in the out of date training manual, RFM and checklists I have to hand.

Having said that the much bigger question is “How and why the helicopter ended up in the water.”

EDIT : Looking at the video of the recovery it seems to show that the landing gear was fully extended but damaged during recovery. Tail rotor appears to rotate when the rotor head moves once lines were attached to the head during the recovery.

[212man]

The video Albatross refers to is here: https://www.nrk.no/vestland/havarikommisjonen-viser-frem-helikoptervraket-etter-havariet-utenfor-sotra-1.16788445?fbclid=IwAR1k9eL2oPfrE2L-PFmYJCODjuO2Vpad1Sk0kDlzK4QxUb8stI-_d7Wrqqk_aem_AUPatMxlO0hfMxg4M_lrPsjfSyhm_twVD8uLa6OQyTRyY3U 6PgYartXZ9-d4QJSt8lE

mystery of the gear now solved!

[jimf671]

The video Albatross refers to is here: https://www.nrk.no/vestland/havarikommisjonen-viser-frem-helikoptervraket-etter-havariet-utenfor-sotra-1.16788445?fbclid=IwAR1k9eL2oPfrE2L-PFmYJCODjuO2Vpad1Sk0kDlzK4QxUb8stI-_d7Wrqqk_aem_AUPatMxlO0hfMxg4M_lrPsjfSyhm_twVD8uLa6OQyTRyY3U 6PgYartXZ9-d4QJSt8lE

mystery of the gear now solved!

Yes. The difference between design for compression and design for tension ably demonstrated?

[HeliComparator]

The video Albatross refers to is here: https://www.nrk.no/vestland/havarikommisjonen-viser-frem-helikoptervraket-etter-havariet-utenfor-sotra-1.16788445?fbclid=IwAR1k9eL2oPfrE2L-PFmYJCODjuO2Vpad1Sk0kDlzK4QxUb8stI-_d7Wrqqk_aem_AUPatMxlO0hfMxg4M_lrPsjfSyhm_twVD8uLa6OQyTRyY3U 6PgYartXZ9-d4QJSt8lE

mystery of the gear now solved!

It does also show that the TR was still connected to the MR. You can see the TR moving when the MRH rotates slightly.

[snakepit]

The visual facts as can be derived from the recovery video as far as I can see:

The aircraft fuselage and undercarriage was intact on the seabed and the only damage seemed to be to the MRBs,
The MRBs damage was consistent with a forced stop while turning at speed
The float system was not deployed
The TRDS was intact but the TRBs were mostly undamaged (in comparison to the MRBs)
Main undercarriage torn off during recovery operation
Aircraft dinghy's were not in their stowage locations in the front of the sponsons

What can be logically deduced from above and other details of the incident:

Water impact was not at 'high' speed either vertically or laterally (fuselage largely undamaged and occupants physically able to conduct emergency exit)
Fuselage remained on or very near the surface despite lack of floats, for sufficient time for the 6 crew to evacuate
MRBs impacted the water such that the head had near stopped before the TRBs impacted the water (nose down or sideways roll?)

That's all I have got.

[OnePerRev]

The recent press conference revealed little new information. The following was said:

-So far no technical malfunction that could explain what happened has been found.
-The CVR/FDR memory unit is being dried at the AAIB facilities and should be downloaded by this time tomorrow.

A video of the salvage operation has been added here (https://www.nsia.no/Aviation/Investigations/24-203).
In the video, we can see the gear were down, broke during retrieval. We also see the tail spinning in concert with the main rotor head, indicating tail drive train connection still intact. Given the crew has been interviewed, this looks like a CDR verification of situational event.

[212man]

I just looked through my very old training manual (2006 FSI) and, of course, it does not describe the electrical circuits for the floats! It does show, however, that for the liferaft jettison there are both DC Primary and Battery Bus circuits, implying you can jettison the liferafts with just the battery, so it seems odd that the floats are not the same - unless the logic was that the rafts might be deployed after shutdown, with the AC Generators offline. Similarly, there is no figure given for the lowest Nr when the AC Generators will drop offline (and hence the DC Primary Busses), other than the fact that the frequency under-protection is not active when airborne, so the Nr will be much lower than the 95% used with ground logic. ( PS - for non-S92 drivers, the AC Generators are driven by the MGB, and are not engine starter/generators.)

Igor13 - it would be good to have some references to your facts, if possible. Regardless, if the 80% Nr figure you quote for the generators dropping off is correct, it is hard to think of a scenario where that could happen. Certainly not OEI, and double, simultaneous, flame-out is almost impossible to imagine. Plus, if the aircraft hit the water with less than 80% Nr, there is no way it would be that undamaged.

[albatross]

Another question that I am sure will be asked and answered during the investigation.

“What was the relative wind direction and speed as the aircraft decelerated towards zero groundspeed using the SAR function?”
Provided, of course, such was the case at the time.
.

[HeliComparator]

I just looked through my very old training manual (2006 FSI) and, of course, it does not describe the electrical circuits for the floats! It does show, however, that for the liferaft jettison there are both DC Primary and Battery Bus circuits, implying you can jettison the liferafts with just the battery, so it seems odd that the floats are not the same - unless the logic was that the rafts might be deployed after shutdown, with the AC Generators offline. Similarly, there is no figure given for the lowest Nr when the AC Generators will drop offline (and hence the DC Primary Busses), other than the fact that the frequency under-protection is not active when airborne, so the Nr will be much lower than the 95% used with ground logic. ( PS - for non-S92 drivers, the AC Generators are driven by the MGB, and are not engine starter/generators.)

Igor13 - it would be good to have some references to your facts, if possible. Regardless, if the 80% Nr figure you quote for the generators dropping off is correct, it is hard to think of a scenario where that could happen. Certainly not OEI, and double, simultaneous, flame-out is almost impossible to imagine. Plus, if the aircraft hit the water with less than 80% Nr, there is no way it would be that undamaged.

I'm assuming the floats have to be armed before the AFDS can operate? If the AFDS is from the battery then presumably the floats were not armed? Surely if you were going to be doing low and slow over water (trans down) then you would arm the floats as SOP?
You should be able to tell which circuit(s) the AFDS is on just by looking at the breaker panels. There will presumably be one for the battery-only bus and ones for the other buses. A good photo of the breaker panel should reveal whether there is one labelled "AFDS" on the battery-only panel.

[Apate]

All documentation I can find (RFM supplement, MM & training material) states that the float system has dual power feed, with either power feed providing complete functionality of the Flotation System. To quote "The floats can either be activated automatically by two interconnected immersion actuators, one inside each main landing gear well or alternatively by pilot operated collective grip switches. The system has dual power supplies, the No.1 DC PRIMARY bus and the BATTERY bus; each is capable of activating the system."

Of course, if the system wasn't armed by the crew then they won't inflate.

AC generators will drop offline between 80% and 85% Nr when not WOW.

[albatross]

I'm assuming the floats have to be armed before the AFDS can operate? If the AFDS is from the battery then presumably the floats were not armed? Surely if you were going to be doing low and slow over water (trans down) then you would arm the floats as SOP?
You should be able to tell which circuit(s) the AFDS is on just by looking at the breaker panels. There will presumably be one for the battery-only bus and ones for the other buses. A good photo of the breaker panel should reveal whether there is one labelled "AFDS" on the battery-only panel.

I think we may be chasing down the wrong rabbit hole here and also grinding the coffee much too fine.
There is, from what I can find, a CB Labeled FLOATS 7.5 amps on BOTH the #1 Primary DC Bus and the Battery Bus. There is NOT any CB labeled AFDS on any Bus that I can find.

Somewhere I have a fold out poster from “Training Daze” at FSI that shows the actual CB panel but a quick “Op Frantic Search” did not find it.


https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/1395x301/img_7500_073fa6c94d2dc9999ec880aac4ebf97d58435723.jpeg
https://cimg0.ibsrv.net/gimg/pprune.org-vbulletin/1917x1726/img_7501_74a981a7d90a56ac671bbfffd5cbbf9a1cb8b3ff.jpeg
https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/940x2000/img_7502_9bad23580f56c85cd47038f2df67b92e699b722b.jpeg

[P3 Bellows]

https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/938x1139/img_0219_e5ccd2aac0eab727c7ba4497236a5bbbbb156698.jpeg
https://cimg9.ibsrv.net/gimg/pprune.org-vbulletin/1821x706/img_0218_fd942a44d0f44e76f094f270c78adc82c022a8d9.jpeg
https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/528x134/img_0217_bb0e5758803e7287962d3d7903ccb6c048c06401.jpeg
The above text from the current S92 RFM. The system is dual powered and there are no warnings in the RFM about having to use the manual deploy with no mains generated power.

[P3 Bellows]

https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/1204x1546/img_0220_d09c6bc5af15417cf517c5b57e14ebbd8466987d.jpeg

[Apate]

"There is NOT any CB labeled AFDS on any Bus that I can find."

You won't because HC was talking Bristow Scottish Puma speak, it's a very specific language that even the best AI tools will struggle to translate :O.

The CBs you found "FLOAT PWR" are the ones that are associated with the Floatation System. The "Automatic Flotation Deployment System" is not an add-on, it is a fundamental part of the system design.

[Magjam]

https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/1054x478/capture_085c0f0202569d005813576cabad16bb1c81d865.jpg

Looks like the outer winch hook is missing.

[212man]

https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/1054x478/capture_085c0f0202569d005813576cabad16bb1c81d865.jpg

Looks like the outer winch hook is missing.
good spot. I looked earlier at the underwater pictures for the same clues

[albatross]

"There is NOT any CB labeled AFDS on any Bus that I can find."

You won't because HC was talking Bristow Scottish Puma speak, it's a very specific language that even the best AI tools will struggle to translate :O.

The CBs you found "FLOAT PWR" are the ones that are associated with the Floatation System. The "Automatic Flotation Deployment System" is not an add-on, it is a fundamental part of the system design.

I understand that. My comment was because HC seemed to allude to a separate Automatic Float Deployment System CB that powers the immersion switches and is only on a primary bus and not on the Batt Bus therebye requiring pilot manual activation if the Nr decreases to a point that the Gens go off line. So I searched for one and did not find a AFDS CB and posted that I did not locate one, nor did I think I would.
Thanks to P3 Bellows for posting the CB Panel schematics and other info.
Furthermore I think the Floats Armed caption #2 explanation is to WARN you the floats are ARMED when you are on the ground, floats are armed and the Nr is below 80% leading to the gens going offline leading to some dark screens if the APU is not on.
https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/1395x301/img_7500_4877d59041e9fc5344c062d9d02b894e6c2f4b29.jpeg

[HeliComparator]

"There is NOT any CB labeled AFDS on any Bus that I can find."

You won't because HC was talking Bristow Scottish Puma speak, it's a very specific language that even the best AI tools will struggle to translate :O.

The CBs you found "FLOAT PWR" are the ones that are associated with the Floatation System. The "Automatic Flotation Deployment System" is not an add-on, it is a fundamental part of the system design.

Yes fair enough. I am just examining why the floats weren’t deployed. After all, lots of pilots spend lots of time arming and disarming the floats in routine operations, but if when the **** hits the fan the floats don’t deploy, it is all a bit pointless.

The Bristow system had 4 float switches. It required any two to be activated, to fire the floats. This meant that one spurious activation wouldn’t fire the floats, and also that one or two switches that failed to activate when immersed wouldn’t prevent the floats from firing. This was a good design with inherent redundancy,

The 92 has 2 float switches, what is the logic? Do both float switches have to activate to fire the system? Or just one?

Anyway as I said, when a last resort emergency life-saving system failed to operate, it means that that system is badly designed and not worth installing. And in this case it probably cost a life.

[HeliComparator]

I understand that. My comment was because HC seemed to allude to a separate Automatic Float Deployment System CB that powers the immersion switches and is only on a primary bus and not on the Batt Bus therebye requiring pilot manual activation if the Nr decreases to a point that the Gens go off line. So I searched for one and did not find a AFDS CB and posted that I did not locate one, nor did I think I would.
Thanks to P3 Bellows for posting the CB Panel schematics and other info.
Furthermore I think the Floats Armed caption #2 explanation is to WARN you the floats are ARMED when you are on the ground, floats are armed and the Nr is below 80% leading to the gens going offline leading to some dark screens if the APU is not on.


Just for clarity I have no idea how the S92 float system is designed or wired. Never flown it (apart from the demonstrator), I was just following up on a couple of other people who seemed certain that the AFDS element of the system was not powered when there was no generated power on the aircraft.

[SARBUOY1]

Interesting that the winch hook is missing, I am assuming that the crew were possibly carrying out winching evolutions between 17:50 and 18:20 looking at the the altitude and speed profiles. If the hoist was not isolated correctly on departure from the the hover, the aircraft then climbs and accelerates to 1000' and 80-100kts. Purely on assumption, if the winch were to have reeled out uncommanded due to a faulty pendant or faulty control circuit; with no weight on the hook at 80-100kts..........where is the winch cable going?

Maybe just pure speculation, but if the un-weighted cable were to have found itself around the rotor head/ tail rotor, it wouldn't be pretty.

[monkey_see]

The information about the automatic / manual deployment is in Section 3.

https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/1088x1516/screenshot_2024_03_05_at_6_18_36_am_9e2f3fb776c9ee8ada67b598 f5e54d151c1be48d.png

[HeliComparator]

The information about the automatic / manual deployment is in Section 3.

https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/1088x1516/screenshot_2024_03_05_at_6_18_36_am_9e2f3fb776c9ee8ada67b598 f5e54d151c1be48d.png
Well that seems quite categoric, a badly designed system lacking in sensible real world analysis, that probably cost someone their life. And nobody saw fit to complain in the preceding 20 years.

[AAKEE]

https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/1054x478/capture_085c0f0202569d005813576cabad16bb1c81d865.jpg

Looks like the outer winch hook is missing.

Hoist wire spooling out by itself after the hoist excercise ?(forgotten the hoist ON?) , at speed reduction hoist wire swinging up in the rotor causing damage and vibrations leading to a decision to ditch?

Or hoist cable cut when the plan was to activate the floats? (I can see that happening, being prepared for hoist cut during the hoist ex.)
From memory, on a similar type the hoist cable could not be cut unless out at least 0.6m.

[albatross]

The information about the automatic / manual deployment is in Section 3.

https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/1088x1516/screenshot_2024_03_05_at_6_18_36_am_9e2f3fb776c9ee8ada67b598 f5e54d151c1be48d.png

Thanks Monkey_see

That info should be very prominently noted on the ECL for Ditching.
It is not on Rev 3 March 2009 which is the latest I have access to.


So the questions are now going to be:
Why did the helicopter impact the water?
Were the floats armed?
Has there been any changes to the float system since May 2012 which would provide for automatic activation when operating on Batt. Power only?
Was the RPM low enough upon water contact to have taken the Generators off line causing the float system to rely on Batt. Power only.
Were the crew aware of this limitation and did the crew attempt to activate the floats manually?

[212man]

Well that seems quite categoric, a badly designed system lacking in sensible real world analysis, that probably cost someone their life. And nobody saw fit to complain in the preceding 20 years.
I think you have jumped to a conclusion that does not bear close scrutiny. I think the only scenario your comment holds true for, is that the floats were armed but there was a fault in the electrical circuit that prevented the AFDS from functioning, where a second Batt Bus circuit would/might have mitigated. Given that we have established that the Generators remain on line (and hence the DC Buses are powered) down to 80% Nr, I find it completely implausible that this aircraft touched down with the Nr below that value, with the absence of damage we see.

I guess there is one key question - was the ditching intentional or unintentional? If the former, then I would not expect the crew to rely on AFDS anyway and would fire the floats manually before touchdown. If unintentionally, then I suspect the balance of probability is that the floats were not armed.

Interestingly, i this article is quotes the investigators as saying they believe there was a technical failure, but I also wonder if his comments have not translated well:https://www.nrk.no/vestland/havarikommisjonen-viser-frem-helikoptervraket-etter-havariet-utenfor-sotra-1.16788445 (use Chrome for automatic translation)

After the press conference at Haakonsvern on Monday, NRK directs questions to Halvorsen specifically about this.

- The helicopter depends on the floats to stay afloat, given that it ends up on the lake. It is so that people can get out within a reasonable time, and so that the helicopter can stay afloat on a straight keel, explains Halvorsen and states:

- Here it has not done so, and we do not know why the floating elements have not come out. That is one of the things we will look into.

- So it's a technical failure?

- Many points to technical failure, without us knowing what lies behind the technical failure. We now hope that the tachograph will contain data that can provide answers to the floats. It will be important to ensure the safety of those who are out flying

[HeliComparator]

I think you have jumped to a conclusion that does not bear close scrutiny. I think the only scenario your comment holds true for, is that the floats were armed but there was a fault in the electrical circuit that prevented the AFDS from functioning, where a second Batt Bus circuit would/might have mitigated. Given that we have established that the Generators remain on line (and hence the DC Buses are powered) down to 80% Nr, I find it completely implausible that this aircraft touched down with the Nr below that value, with the absence of damage we see.


I've never done an engine off landing in an S92, but surely it is not beyond the bounds of possibility that a frantic hauling up of the collective with no engine power could not dip the Nr below 80% just before water impact? I suppose there is also a question of how long it takes for the alternators to go off line and bus ties to open once the Nr gets below 80%. It won't be instant but it might be quite quick.
It is all speculation of course, but I maintain that it is bad design to have an ultimate last resort life saving device not powered by the ultimate last resort electrical power source. What justification would there be for not having a supply from the battery to the float switches? It is not as if there could be any significant power drain in normal operation. And it does seem odd that there is a CB for manual float inflation on the battery bus, but the blurb posted suggests that this doesn't include powering the float switches. It all seems rather odd.
Do you know what the logic is for the float switches? Does it require any one switch, or both switches to be activated?

[GenuineHoverBug]

Interestingly, i this article is quotes the investigators as saying they believe there was a technical failure, but I also wonder if his comments have not translated well:https://www.nrk.no/vestland/havarikommisjonen-viser-frem-helikoptervraket-etter-havariet-utenfor-sotra-1.16788445 (use Chrome for automatic translation)

I believe they just got too vague in replying to suggestions, rather than questions, from the media after the press conference. As far as I heard, they only agreed there could have been a technical problem with the system. There was no suggestion in their statement that they had examined it and they rather said they did not know why it had not inflated, and that would be an important path to follow in the investigation.

[SASless]

Remember the NYC Sightseeing helicopter ditching that killed five passengers who were unable to exit the aircraft as they were wearing safety harnesses with tethers?

Accident happened in 2018 and the Accident Report was issues in December of 2019.

In that accident the floats partially inflated when only one bottle discharged due to a system anomaly and in the report it was stated that resulted in partial inflation of all floats but less than full inflation would not result in the aircraft staying upright.

From that Report's recommendation to the US FAA. (My bolding of the first sentence)

Review the activation system designs of Federal Aviation Administration-approved rotorcraft emergency flotation systems for deficiencies that may preclude their proper deployment, such as a lack of a means to identify high pull forces on manual activation handles or inadequate guidance on the intended use of the activation system, and require corrective actions based on the review findings.




A question I would ask is exactly what kind of review did the FAA conduct?

Other findings in that Report noted the lack of adequate and proper oversight of the Flight Operations of the Operator by the FAA.

Point of this post.....what role does the Certification Authorities play in the design, testing and approval of Helicopter Emergency Floatation Systems?

Will we see similar language coming forth in the accident report of the ditching in this tragedy if it is found there was a design failure in the float system?

[212man]

I believe they just got too vague in replying to suggestions, rather than questions, from the media after the press conference. As far as I heard, they only agreed there could have been a technical problem with the system. There was no suggestion in their statement that they had examined it and they rather said they did not know why it had not inflated, and that would be an important path to follow in the investigation.
Thanks - I did find it a bit unlikely they would make such a bold statement so early

[212man]

I've never done an engine off landing in an S92, but surely it is not beyond the bounds of possibility that a frantic hauling up of the collective with no engine power could not dip the Nr below 80% just before water impact? I suppose there is also a question of how long it takes for the alternators to go off line and bus ties to open once the Nr gets below 80%. It won't be instant but it might be quite quick.
It is all speculation of course, but I maintain that it is bad design to have an ultimate last resort life saving device not powered by the ultimate last resort electrical power source. What justification would there be for not having a supply from the battery to the float switches? It is not as if there could be any significant power drain in normal operation. And it does seem odd that there is a CB for manual float inflation on the battery bus, but the blurb posted suggests that this doesn't include powering the float switches. It all seems rather odd.
Do you know what the logic is for the float switches? Does it require any one switch, or both switches to be activated?

I think it is very probable that the Nr would decay below 80% during the final flare and, yes, in that situation it would be desirable to have the AFDS functioning. I agree that having the AFDS powered by the Batt Bus is probably a desirable feature. However, I do not believe it is at all plausible that this aircraft hit the water with no engine power and Nr below 80% which is why I suggested your statement about the probable loss of life being connected was unfounded.

Regarding the AFDS power logic, I think we need to step back a bit and consider the whole design and philosophy of the electrical system, which is nothing like a Super Puma. There are three key differences:

The engines are pneumatically started
The Generators run off the MGB
It has an APU, which is used to provide the air for engine starting and acts as the emergency electrical supply

So, essentially, the battery is only there to start the APU. Also, most scenarios that will result in a ditching require the APU to have been started. I think, in this context, the idea of not having the AFDS powered by the Batt Bus is much more understandable than it would be in an aircraft with engine starter/generators and no APU.

[SASless]

That is a very astute observation and makes very good sense.

Follow up question would be to determine what SOP's pertain to t he operations being carried out by the Crew and did those SOP's dictated starting the APU as part of the Checklist or Standard Procedures.

Also, is there such language in the RFM that lays out that requirement?

[HeliComparator]

I think it is very probable that the Nr would decay below 80% during the final flare and, yes, in that situation it would be desirable to have the AFDS functioning. I agree that having the AFDS powered by the Batt Bus is probably a desirable feature. However, I do not believe it is at all plausible that this aircraft hit the water with no engine power and Nr below 80% which is why I suggested your statement about the probable loss of life being connected was unfounded.

Regarding the AFDS power logic, I think we need to step back a bit and consider the whole design and philosophy of the electrical system, which is nothing like a Super Puma. There are three key differences:

The engines are pneumatically started
The Generators run off the MGB
It has an APU, which is used to provide the air for engine starting and acts as the emergency electrical supply

So, essentially, the battery is only there to start the APU. Also, most scenarios that will result in a ditching require the APU to have been started. I think, in this context, the idea of not having the AFDS powered by the Batt Bus is much more understandable than it would be in an aircraft with engine starter/generators and no APU.


Well just on your bullet points, the second one is the same as the Super Puma. I don’t know when the APU is routinely started, other than at start up. For example I don’t think it is started prior to a normal landing or a low level SAR hover? Is it just started in response to some first level failure eg a generator failure? My point is that an APU is only any use if it is on, and it takes a while to start up so in the event of a sudden fairly catastrophic issue it is of no use. Of course the emerg checklist will have lots of progressive scenarios that could ultimately result in ditching after several minutes, but the real world is not always so reasonable and predictable.

And surely that is what the float switches are for - not for an emergency checklist led ditching - you press the button for that - it is for when arriving in the water is sudden and unexpected.

[212man]

That is a very astute observation and makes very good sense.

Follow up question would be to determine what SOP's pertain to t he operations being carried out by the Crew and did those SOP's dictated starting the APU as part of the Checklist or Standard Procedures.

Also, is there such language in the RFM that lays out that requirement?
'Astute' is my middle name! :}

[SASless]

Well it did start with an A....and end with an E so close enough I guess.:rolleyes:

[212man]

Well just on your bullet points, the second one is the same as the Super Puma. I don’t know when the APU is routinely started, other than at start up. For example I don’t think it is started prior to a normal landing or a low level SAR hover? Is it just started in response to some first level failure eg a generator failure. My point is that an APU is only any use if it is on, and it takes a while to start up so in the event of a sudden fairly catastrophic issue it is of no use. Of course the emerg checklist will have lots of progressive scenarios that could ultimately result in ditching after several minutes, but the real world is not always so reasonable and predictable.
Sorry, it was 35 years ago since I did my groundschool and I'd forgotten about the generators, although I do still recall 20" OEI transient is 34,900 rpm!

Some operators do start the APU before landing, but I have no clue if Bristow Norway do, or for SAR low level. It is possible, because the first time I encountered the practice was with ex-Norsk pilots that joined us, who wanted to continue the practice.

[Lonewolf_50]

I don’t know when the APU is routinely started, other than at start up.
Some operators do start the APU before landing, but I have no clue if Bristow Norway do, or for SAR low level. It is possible, because the first time I encountered the practice was with ex-Norsk pilots that joined us, who wanted to continue the practice. I am not sure how similar to the Blackhawk / Seahawk is to the S-92 is, but...we usually started the APU for winching ops, since it also powered the utility hydraulic system, and we usually started the APU on the ground at landing, before shut down for field ops, but started the APU before we landed on the ship for over water ops.
I of course defer to S-92 operators on the detail, but I suspect the system/scheme would be similar.
(On the other hand, our Navy ended taking the floats off of the Seahawks due to a problem with them interfering with the crew exit from the cockpit, so it appears that S-92 is better set up with the floats, perhaps due to a few lessons learned).

[snakepit]

Hoist wire spooling out by itself after the hoist excercise ?(forgotten the hoist ON?) , at speed reduction hoist wire swinging up in the rotor causing damage and vibrations leading to a decision to ditch?

Or hoist cable cut when the plan was to activate the floats? (I can see that happening, being prepared for hoist cut during the hoist ex.)
From memory, on a similar type the hoist cable could not be cut unless out at least 0.6m.

On the video the aircraft is initially inverted on the seabed, then the footage changes to it upright but still on the seabed. At 1:13 to run you can clearly see the aircraft now upright and the twin hoist is separated from the hoist support strut with the outboard hook missing. It is possible that the missing hook was ripped off when the hoist mount was damaged. It is also possibly that the hoist frame was used to right the fuselage, though why they then attempted the fuselage recovery using the undercarriage I cannot guess? Possible the video is not stitched together chronologically?

[Aser]

I guess there is one key question - was the ditching intentional or unintentional? If the former, then I would not expect the crew to rely on AFDS anyway and would fire the floats manually before touchdown.

Careful with that, the insurance company may decide not to pay or if you are in the wrong country, you may find yourself in court... when the system is designed for float activation AFTER water entry...

[60FltMech]

Lonewolf, I’m assuming if you were starting the APU for winching ops for utility hydraulics, the hoist motors were powered by hydraulics? Us Army H-60 hoists are all electric now, though I think in the past some were hydraulic and Navy systems may still be?

Remember also that the battery utility bus powers the fire suppression system for #1 Eng and APU, converted AC power to the DC primary bus is required for the #2 Eng fire suppression to work.

I used to question this lack of redundancy but it’s probably the best compromise in systems design to handle the most likely scenarios for dealing with fires, meaning a situation that ends up with your #2 engine on fire with no converted AC power to fight it means a lot more has gone wrong in your day than just a #2 engine fire.

I think you pointed out, a situation that droops the rotors below 90% that kicks off both generators or cascading failure of the AC electrical system (both AC generators and the APU generators all failing together), would seem unlikely and a power on ditching is probably what happened in this situation, so it becomes more of a possibility of a human factors or SOP issue why the floats weren’t deployed than a systems failure.

FltMech

[albatross]

As I vaguely recall:
Re APU use.
If you are landing offshore for a rotors running turn around AND are planning to go to idle you start the APU pre-landing. We did not usually go to idle. Not going to Idle. —- APU not required.
If for some reason you were doing a lot of quick inter-rig stuff and had to go to idle you just kept the APU running. Of course not exceeding the APU Running VNE of 150 Kts.
If you are going to shut down you start the APU. ( It would be embarrassing to have a hot shutdown and not be able to motor the starter.)
Landing back at base you start the APU when taxing off the runway in to your spot.
Landing at an airport away from base start the APU, shutdown the engines leave the APU running if you are just going to fuel, load. and go.

Before start you start the APU to get the Air conditioning or heating running and do all checklist items up to the actual start.


Electrical problems …start the APU.

If it is SOP to have the APU up and running during SAR hoisting I have no idea.

One question I have asked many times is why you would select gear-down for ditching. ( being an bush float guy in another life—-why would you want gear down causing drag and a nose down pitching movement. if you want to blow it down after landing you could do that the gear is not going to foul the floats.) is it perhaps because of the location of the immersion switches?

[ShyTorque]

Electrical problems …start the APU.

One of the things I really liked about the Blackhawk (the S-70 is my all time favourite). If in doubt, switch on the APU.

[Lonewolf_50]

Lonewolf, I’m assuming if you were starting the APU for winching ops for utility hydraulics, the hoist motors were powered by hydraulics? Us Army H-60 hoists are all electric now, though I think in the past some were hydraulic and Navy systems may still be?
It's been a couple of decades. I'll see what the (very old) CH-60S NATOPS has in it.
EDIT::
2.23 RESCUE HOIST SYSTEM {my note: sometime in the 00's}
{snip} The hoist is hydraulically powered by the backup hydraulic pump. Speed is variable from 0 to 215 fpm for the Breeze-Eastern and 0 to 250 fpm for the Lucas-Western hoist. {snip} The hoist contains 200 feet of usable cable, a guillotine-type cable cutter, and an automatic cable brake. The first and last 20 feet of the cable are bright orange to warn of end approach. The hoist hook is attached to the cable end by a ball-bearing swivel.
Power to operate the rescue hoist system is supplied by the No. 2 dc primary bus through the RSQ HOIST CONTR circuit breaker. Backup (emergency) hoist operation is powered by the dc essential bus through the RSQ HOIST AUX CTRL circuit breaker.
I may have been superimposing my Seahawk memory on my Blackhawk memory, though. The SH-60B's were sun-downed a decade ago and that's what I flew a good while before that.
Remember also that the battery utility bus powers the fire suppression system for #1 Eng and APU, converted AC power to the DC primary bus is required for the #2 Eng fire suppression to work. Yep, thanks for the refresher on systems. :ok:

As to the S-92, does it use an electric motor for its hoist, or does it also use hydraulic power?

[Hot_LZ]

This 92 was dual electric hoists.

LZ

[ShyTorque]

Bearing in mind that the crew survived, what actually happened here will be revealed in time so I, for one, see little point in protracted speculation on the cause. ;)

[206Fan]

https://www.facebook.com/groups/94022021619/permalink/10160918420591620/?mibextid=SphRi8

[60FltMech]

Bearing in mind that the crew survived, what actually happened here will be revealed in time so I, for one, see little point in protracted speculation on the cause. ;)

Very good point as usual. I guess I’m interested in this sort of thing because it gets the old brain cells firing. The amount and variety of experience contained here is great to see and since the off shore world is quite foreign to me these discussions are normally pretty educational.

FltMech

[[email protected]]

What would be far more useful and enlightening would be input from an actual SAR S-92 operator, ideally Bristow.

Any on here?

[helispotter]

On the video the aircraft is initially inverted on the seabed, then the footage changes to it upright but still on the seabed. At 1:13 to run you can clearly see the aircraft now upright and the twin hoist is separated from the hoist support strut with the outboard hook missing. It is possible that the missing hook was ripped off when the hoist mount was damaged. It is also possibly that the hoist frame was used to right the fuselage, though why they then attempted the fuselage recovery using the undercarriage I cannot guess? Possible the video is not stitched together chronologically?

Snakepit: I assume the video to which you refer is that contained in the article link provided by 212man in post #112? That video shows the salvage operation didn't go smoothly. From 00:06 it seems like all three of the undercarriage units are intact with the S-92 inverted on the seabed. It looks like they originally tried to lift it out of the water that way with a sling around each oleo. But at 00:10 it is apparent the wheels had already been pulled off the starboard (right) oleo by the sling connected to it since they are swinging in the breeze. Not clear at what point that undercarriage failed under the strain. Then, as they tried to pull the helicopter above the water (with all the water still trapped in the fuselage), the port (left) wheels / oleo also give way (00:26), leaving only the strap attached to the nose wheel. The helicopter rapidly starts to sink again. My guess is that the strap attached to the nose wheel subsequently also failed, unless it was cut free once helicopter settled back on the seabed. Perhaps on second time around, helicopter was instead resting upright (the footage seen earlier in video, not in chronological order), so obvious choice would then have been to lift it by the main rotor hub. Once lifted free of the water, only the front undercarriage is still in 'one piece' with part of the lifting sling still attached to it.

I see in #132, 206Fan indicated a video of salvage is also posted to Facebook. Perhaps it is the same as in #112, or a more extended version, but it is necessary to join the group to access it.

I wonder whether this S-92 is now only still suitable as a source of spare parts? If so, I hope none of the drivetrain parts critical to flight safety find their way back onto any operational helicopter.

[OttoRotate]

Not sure this design flaw has ever been fixed by Sikorsky other than increased monitoring -

https://skybrary.aero/accidents-and-incidents/s92-west-franklin-wellhead-platform-north-sea-2016

https://www.offshore-technology.com/features/featuregrounded-in-reality-inside-the-sikorsky-s-92-helicopter-investigation-5760853/?cf-view

I believe there were a handful of identical issues going back previously also as they issued an emergency AD just before that accident above.

https://www.ainonline.com/aviation-news/business-aviation/2016-11-28/loss-tail-rotor-authority-prompts-s-92-emergency-ad

Just a post to highlight previous loss of control events. Most likely unrelated to this event but you never know.
The TRPCS seizing did not have a root cause in the design. RCA determined a supplier failed to hold the upper tolerance on the roller bearing size. Bearings were too large, resulting in high heat during normal operation, burning up grease, and ultimately seizing the unit. This is supported by the fact that the AD was limited to low-hour assemblies. The issue was fully resolved at the supplier, all parts in the suspect population were inspected and dispositioned, and there have been no further recorded incidents or escapes.

Replying to a different topic, the recent FAA Emergency Airworthiness Directive AD #: 2024-05-51 (https://drs.faa.gov/browse/excelExternalWindow/DRSDOCID146885804120240229174637.0001). Both Sikorsky and the US Army determined this to be a minor issue requiring no action, but the FAA dissented and forced compliance. I'm curious if anyone here can remember a similar instance with such a dramatic difference in reactions. Regardless, I don't think it played a factor in the thread topic.

[SASless]

What would be far more useful and enlightening would be input from an actual SAR S-92 operator, ideally Bristow.

Any on here?

If so they might want to submit their Resignation Letter ahead of time.

When these matters arise it pays to zip ones lip and sit quietly behind the daily issue of the Guardian or whatever crossword now enjoys with ones Tea.

[[email protected]]

Shame you don't follow your own advice - of course I wasn't suggesting they post under their real name.

Some accurate information about their SAR SOPs instead of random musings about flotation gear might go a long way to explain how they ended up in the water.

[albatross]

Shame you don't follow your own advice - of course I wasn't suggesting they post under their real name.

Some accurate information about their SAR SOPs instead of random musings about flotation gear might go a long way to explain how they ended up in the water.

A very experienced pilot friend and a very smart guy (don’t tell him I said that!) looked at these posts and said “Humm aren’t you folks getting focused on the seaworthiness of the lifeboats on the Titanic and kind of ignoring the cause of the ship hitting the iceberg?” He has a way of saying things like that. He will not post on aviation sites and seldom, if ever, even looks at them, except when I occasionally drag him, kicking and screaming, over to my computer screen. He has a point.

[212man]

A very experienced pilot friend and a very smart guy (don’t tell him I said that!) looked at these posts and said “Humm aren’t you folks getting focused on the seaworthiness of the lifeboats on the Titanic and kind of ignoring the cause of the ship hitting the iceberg?” He has a way of saying things like that. He will not post on aviation sites and seldom, if ever, even looks at them, except when I occasionally drag him, kicking and screaming, over to my computer screen. He has a point.

I think that’s given - clearly the cause is of paramount interest. But…..whatever that cause was, they ended up in the water and the result was not what we would all expect. Even the Malaysian 139 that fell out of the sky, spinning, a few days ago, had inflated floats!

[snakepit]

A very experienced pilot friend and a very smart guy (don’t tell him I said that!) looked at these posts and said “Humm aren’t you folks getting focused on the seaworthiness of the lifeboats on the Titanic and kind of ignoring the cause of the ship hitting the iceberg?” He has a way of saying things like that. He will not post on aviation sites and seldom, if ever, even looks at them, except when I occasionally drag him, kicking and screaming, over to my computer screen. He has a point.

I think what you’re seeing is not a lack of interest from aviators as to why it occurred, but (somewhat surprisingly for prune) a restraint in pointless guesswork as to the cause. I’d like to think in respect to the deceased and crew who are going through a very difficult time, but also because there’s insufficient information to make any assumptions and we will know soon anyway due to there being survivors.

There is however, a significant amount of information that can be discussed about the post accident events gleaned from open source information.

[SASless]

Of course there is the absence of witness accounts, no video of the accident as it occurred, and other differences from other similar events.....such as the in the other accident a few days before this one.

Witness accounts always engender discussion as they can vary greatly and of course watching a video of something happening presents a great many opportunities for discussion.

The float discussion was just one topic that is of course relevant and as we have seen leads off in several directions as it should.

In time there will be yet more such issues that shall be ripe fruit for examination.....including what caused the aircraft to wind up in the water.

What lessons are learned if there is no discussion amongst professionals of the factors surrounding a crash?

[Scorpygixxer]

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/773x1366/screenshot_20240309_074232_duckduckgo_9f3427cd6b86b36b733130 c53f0085cd03c77857.jpg
Looks like cable hanging below the tail boom. That doesn't look like water impact damage there either.

[megan]

Black striations on tail rotor paddles? Wire from the hoist?

[212man]

Black striations on tail rotor paddles? Wire from the hoist?
The cabin door was closed, so seem unlikely to be hoist cable - more like TR control cables?

[Hot_LZ]

If you watch the video of the recovery you’ll understand why the tail has that damage.

LZ

[212man]

If you watch the video of the recovery you’ll understand why the tail has that damage.

LZ
Yes - it gets a good smashing twice!

[GenuineHoverBug]

An update (https://havarikommisjonen.no/Luftfart/Undersokelser/24-203) from NSIA (only in Norwegian so far) states that the floats were armed, but (obviously) did not inflate.
They speculate that it could be because the sequence of events managed to outsmart the design criteria.

[megan]

The cabin door was closed, so seem unlikely to be hoist cable - more like TR control cables?Just wondering 212, given one of the hoist hooks was missing, wonder too if that white streak (abrasion mark?) below where the hook should be is indicative of anything. Will come out in the wash.


https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/1054x478/capture_085c0f0202569d005813576cabad16bb1c81d865_07031c7513b ad981256e5f12ae6e9cd0d8579af1.jpg

[212man]

An update (https://havarikommisjonen.no/Luftfart/Undersokelser/24-203) from NSIA (only in Norwegian so far) states that the floats were armed, but (obviously) did not inflate.
They speculate that it could be because the sequence of events managed to outsmart the design criteria.
Update March 8, 2024The investigation is still in an early phase. The Accident Investigation Board has interviewed the five who survived the accident. Together with analysis of data from the tachograph, this is important information to be able to understand why the accident could have happened. There is good dialogue with the parties involved. All findings that are significant for flight safety will be immediately given to the Norwegian Civil Aviation Authority and to the European Aviation Authority, EASA. The American Accident Investigation Board, NTSB, is associated with the investigation with an accredited representative.

So far, no significant discoveries have been made that affect the immediate flight safety.

The survey will also include survival possibilities. This includes both the helicopter's and crew's equipment, the possibility of evacuation and the rescue operation itself.

The helicopter was equipped with floats. These were armed, but were not automatically triggered in the event of a collision with the sea. The flotation elements for the helicopter type are designed for a controlled emergency landing on water. Although the accident appears to have had limited energy when it collided with the sea, it cannot be described as a controlled emergency landing. The fact that floats were not resolved may be because the situation that arose was outside the system's limitations. The Accident Investigation Board cannot thus far say that there is a technical fault with the floats.

.....

[DOUBLE BOGEY]

Someone dies, this creates an opportunity for some childish bickering and point scoring. Rather sad.
I miss the childish bickering HC, RH gets boring when we all play nicely!