Bristow S92 down west of Bergen Norway
Avoid imitations
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Possibly. I’m sure all will become clear in due course.
Join Date: Sep 2012
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The 92 TRDS routing is pretty well enclosed within the pylons, which do appear 'unstruck' in the photo.
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?
The following 2 users liked this post by HeliComparator:
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.
-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.
The following users liked this post:
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.
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.
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 Ł 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!
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 Ł 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!
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It's a Sikorsky. Teflon helicopter company.
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.
Last edited by albatross; 4th Mar 2024 at 14:31. Reason: Comment added
The video Albatross refers to is here: https://www.nrk.no/vestland/havariko...tXZ9-d4QJSt8lE
mystery of the gear now solved!
mystery of the gear now solved!
The video Albatross refers to is here: https://www.nrk.no/vestland/havariko...tXZ9-d4QJSt8lE
mystery of the gear now solved!
mystery of the gear now solved!
The video Albatross refers to is here: https://www.nrk.no/vestland/havariko...tXZ9-d4QJSt8lE
mystery of the gear now solved!
mystery of the gear now solved!
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
- 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?)
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.
-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.
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.
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.
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.
.
“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.
.
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.
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.
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.
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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.
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.
Last edited by Apate; 4th Mar 2024 at 17:01.
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.
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.
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.
