Bristow S92 down west of Bergen Norway
"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
.
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.
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
.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.
"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.
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.
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
.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.
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.
Last edited by albatross; 4th Mar 2024 at 19:14.
"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.
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.
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
.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.
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.
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.
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.
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Winch hook missing
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.
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.
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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.
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.
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?
Last edited by albatross; 4th Mar 2024 at 22:55.
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/havariko...tra-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
- 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
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.
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?
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/havariko...tra-1.16788445 (use Chrome for automatic translation)
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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)
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?
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.
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?
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.
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?
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?
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
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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?
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?
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:
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
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.
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?
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?
