Helicopter down - North Sea Dutch sector
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Farmer1,
I think, looking at the pictures, that it is the "angle of the dangle".
The droop and washout on those blades tends to look a bit like that, and when you look at the other pictures it does not look as obscure.
I think, looking at the pictures, that it is the "angle of the dangle".
The droop and washout on those blades tends to look a bit like that, and when you look at the other pictures it does not look as obscure.
Combine Operations
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I think we'll agree to differ, HeliEng. The pitch at the blade root looks about 45 degrees. I can't see how that could be possible, and if it were, all the blades would be the same if the collective lever were locked down (I assume it is lockable on the Puma). The other blades seem to have flat pitch.
Anyway, time will tell. Thank God they all lived to be able to tell their grandchildren.
Anyway, time will tell. Thank God they all lived to be able to tell their grandchildren.
Farmer 1, it looks fairly normal to me (as an ex puma driver). Although the collective might be locked down, I bet the cyclic isn't locked. If the aircraft has been bobbing around in the sea for a few days, the controls will have been moving a fair bit.
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Looks like I'm in a minority against people who are more knowledgeable on the subject than I am.
Hopefully, others with even more knowledge will eventually find the truth.
Neck wound in, but maybe not completely.
Hopefully, others with even more knowledge will eventually find the truth.
Neck wound in, but maybe not completely.
Can someone in the know answer a question - Ditching at night, not an easy choice for anyone. Were they able to use SAR equipment (FLIR, Search Lights etc for the ditching) or was it a 'seat-of-the-pants' descent into the water ?
Either way, job well done.
Either way, job well done.
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north sea landing
Nice to see that the blades were parked properly. I wonder why the 'other' engine didnt keep the thing in the air. being an ex-cynic off the North Sea I thought the Puma2 was supposed to be better than the others.
Good to see all inflation equipment worked as published
.
Good to see all inflation equipment worked as published
.
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Andy P
Read the whole post and you will see the possible reasons for the ditching which may also explain why the 10 o'clock blade looks slightly odd in pitch.
The L2 will fly well on one engine
332M
Read the whole post and you will see the possible reasons for the ditching which may also explain why the 10 o'clock blade looks slightly odd in pitch.
The L2 will fly well on one engine
332M
Taken from below the rotor disc, the 10°Clock Blade may appear to have higher than expected pitch, but this is countered by the opposing blade at the 4°Clock position having very little pitch, just as you would expect.
Only a thought…...
Only a thought…...
Last edited by Hilife; 27th Nov 2006 at 05:46.
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Hililife
What I was alluding to reference the blade angle was that if the alleged control locking was due to a hydraulic problem, then the blades could be at odd angles due to uneven draining of the servo jacks, especially after several hours bobbing around in the N Sea
332M
What I was alluding to reference the blade angle was that if the alleged control locking was due to a hydraulic problem, then the blades could be at odd angles due to uneven draining of the servo jacks, especially after several hours bobbing around in the N Sea
332M
Control locking
In a high wind any AS332 blades will tend to tilt the stars over time when it is shut down and this leads to the blades being at odd angles. To prevent this later 332,s have locking rods on the floor so that the cyclic can be held central. Another locking bar for he collective looks after that. Whether GJSAR had them I would't know but it would be the last thing I would think of if I was jumping out of it into a dinghy at night.
Good on the crew. I wouldn't like to ditch anything, let alone in the dark, thank you very much.
Good on the crew. I wouldn't like to ditch anything, let alone in the dark, thank you very much.
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On the HUMS Topic, this presents an interesting case, since here we have an aircraft with engine problems in flight. The engine manufacturer in this case does not believe in rejecting engines for faults based on data collected by HUM systems in flight, only engine run up / run down vibration data. If this instance COULD have been detected by a HUMS, then perhaps the engine manufacturer needs to drag its sorry french arse out of the dark ages, and re-evaluate its procedures.
Secondly, the topic of cockpit displays has been discussed down the years at CAA and HUMS conferences, and opinions vary. As Mr Helicomparitor points out, HUMS data is only ever of use retrospectively, since data is only downloaded after flight, so then, I would throw the questions open to the crews..
1. Would you want a cockpit display to tell you that your engine was developing a malfunction? Bear in mind the severity of the malfunction would be very difficult to establish in flight, and you might feel you need to ditch, what could be an engine which is sufficient to get you home?
2. Is it not a sorry state of affairs, IF it comes to light, that (Not for the first time) an engine fault could have been detected by collecting vibe data in the cruise as opposed to run up?
Of course my questions in relation to this incident are loose and rely heavily on supposition, however, they may yet prove to be very pertinent, well to those in the HUMS business anyway
.
The AAIB report will make interesting reading.
Again, my congratulations to the crew, technology is one thing, but when you are about to go splash into the North Sea, they have proved that science and technology is no substitute for skill and a huge pair of gonads!!
GW
Secondly, the topic of cockpit displays has been discussed down the years at CAA and HUMS conferences, and opinions vary. As Mr Helicomparitor points out, HUMS data is only ever of use retrospectively, since data is only downloaded after flight, so then, I would throw the questions open to the crews..
1. Would you want a cockpit display to tell you that your engine was developing a malfunction? Bear in mind the severity of the malfunction would be very difficult to establish in flight, and you might feel you need to ditch, what could be an engine which is sufficient to get you home?
2. Is it not a sorry state of affairs, IF it comes to light, that (Not for the first time) an engine fault could have been detected by collecting vibe data in the cruise as opposed to run up?
Of course my questions in relation to this incident are loose and rely heavily on supposition, however, they may yet prove to be very pertinent, well to those in the HUMS business anyway
.The AAIB report will make interesting reading.
Again, my congratulations to the crew, technology is one thing, but when you are about to go splash into the North Sea, they have proved that science and technology is no substitute for skill and a huge pair of gonads!!
GW
It seems so rare for an offshore helicopter to actually end up in the water with the floats deployed so we hardly ever get to study what should be done next. Since GJAX is the SAR machine with a well-trained crew I expect they set a good example, or at least followed what the ditching gods felt should be the procedure.
OK, so now GJAX is bobbing in the water with the floats deployed and 15 pax and 2 crew inside in the pitch black of night 15 miles offshore. Do they leave the battery on and the cabin lights, use the emergency lighting, leave the strobes on to make it easier for the surface rescue boats or other helicopters to find them?
Looks like it floated pretty good since it managed to drift right-side up all night to a beach. Did everyone leave the warm, well-lit cabin and jump into the rafts, were the rafts tethered to the aircraft, anybody slip and fall in the water, did the lights on the lifejackets work? Looking at the pictures of them hoisting the helicopter on the beach can anyone tell if both liferafts were deployed?
Were all 17 winched out of the water or the rafts by another helicopter or did a boat get to them first?
Sorry for all the questions, I always figure I can take care of my end and get it into the water with the floats deployed. It is the afterward that I have nightmares about - maybe pepperspraying panicky passengers, or using that Nigerian crash axe to be more selective on a bad apple that is compromising everyone's safety.
Malabo
OK, so now GJAX is bobbing in the water with the floats deployed and 15 pax and 2 crew inside in the pitch black of night 15 miles offshore. Do they leave the battery on and the cabin lights, use the emergency lighting, leave the strobes on to make it easier for the surface rescue boats or other helicopters to find them?
Looks like it floated pretty good since it managed to drift right-side up all night to a beach. Did everyone leave the warm, well-lit cabin and jump into the rafts, were the rafts tethered to the aircraft, anybody slip and fall in the water, did the lights on the lifejackets work? Looking at the pictures of them hoisting the helicopter on the beach can anyone tell if both liferafts were deployed?
Were all 17 winched out of the water or the rafts by another helicopter or did a boat get to them first?
Sorry for all the questions, I always figure I can take care of my end and get it into the water with the floats deployed. It is the afterward that I have nightmares about - maybe pepperspraying panicky passengers, or using that Nigerian crash axe to be more selective on a bad apple that is compromising everyone's safety.
Malabo
Gael - your point on HUMS may have some general validity, but in this case the ditching was nothing to do with an engine malfunction - there was no power loss or lack of rrpm governing. They ditched because the cyclic was intermittently locking. Whilst there is still no word as to the cause, I very much doubt the root cause was engine related.
Regarding your general point, just what should the HUMS system be monitoring? There follows some general waffle from me, which I hope someone will take issue with!
A factor that makes HUMS relatively easy for transmission monitoring is that the transmission rotational speed is pretty much constant. I suppose this does apply to the power turbine section of the engine, but not to the compressor section.
The variable rotational speed of the compressor section results in a vibration signature that changes dramatically with rpm. Its difficult to set limits or do any clever processing of the data as a result. This is why the manufacturers only use run up / down data and check the max vibration amplitude. This should pick up bearing wear, out of balance etc and these are the sort of faults that tend to progress relatively slowly. Other faults such as cracked combustion chamber, FCU malfunctions etc cannot really be detected by current HUMS technology (other than by power assurance checks.)
The other general point is that there is only one transmission, a complex set of gears and bearings working under high load. Any faults in this can be catastrophic. However there are two engines and assuming you are operating PC 1 or even 2, the chances of an engine failure causing a major problem is remote. This is especially true with aircraft certified to the latest standards as there is now much higher safety required for overspeed situations that previously could have damaged the remaining engine or the aircraft.
The cockpit display question is an old one. When HUMS was developed the decision was made on the grounds that a false warning could result in an unnecessary ditching and loss of life. The technology was (and still is imho) not robust enough to justify a warning that says "ditch now". If the warning is not going to say that, there is not much point in having it.
Helieng - no hint yet as to the cause. EC's only output is a letter informing operators of the bare facts of the ditching - it runs to about 4 lines of text!
HC
Regarding your general point, just what should the HUMS system be monitoring? There follows some general waffle from me, which I hope someone will take issue with!
A factor that makes HUMS relatively easy for transmission monitoring is that the transmission rotational speed is pretty much constant. I suppose this does apply to the power turbine section of the engine, but not to the compressor section.
The variable rotational speed of the compressor section results in a vibration signature that changes dramatically with rpm. Its difficult to set limits or do any clever processing of the data as a result. This is why the manufacturers only use run up / down data and check the max vibration amplitude. This should pick up bearing wear, out of balance etc and these are the sort of faults that tend to progress relatively slowly. Other faults such as cracked combustion chamber, FCU malfunctions etc cannot really be detected by current HUMS technology (other than by power assurance checks.)
The other general point is that there is only one transmission, a complex set of gears and bearings working under high load. Any faults in this can be catastrophic. However there are two engines and assuming you are operating PC 1 or even 2, the chances of an engine failure causing a major problem is remote. This is especially true with aircraft certified to the latest standards as there is now much higher safety required for overspeed situations that previously could have damaged the remaining engine or the aircraft.
The cockpit display question is an old one. When HUMS was developed the decision was made on the grounds that a false warning could result in an unnecessary ditching and loss of life. The technology was (and still is imho) not robust enough to justify a warning that says "ditch now". If the warning is not going to say that, there is not much point in having it.
Helieng - no hint yet as to the cause. EC's only output is a letter informing operators of the bare facts of the ditching - it runs to about 4 lines of text!
HC
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HC,
So your assumption of the cause not being an engine problem is probably correct then! Manufacturers are normally pretty quick to respond to events like this if they believe there are airworthiness issues with their products, and sometimes even when nothing is proven!!!!!
Time will tell I guess!
So your assumption of the cause not being an engine problem is probably correct then! Manufacturers are normally pretty quick to respond to events like this if they believe there are airworthiness issues with their products, and sometimes even when nothing is proven!!!!!
Time will tell I guess!
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HC - Having been in the HUMS game long enough, and probably worked with you at some point or other, I was just asking for general opinion. I too see HUMS as insufficiently developed to be of use as a primary fault warning system.
On the subject of compressors, as you are aware, the offending frequency is easily identified as 1x or 2x etc from the Ng tacho or an MPU. However I'm not advocating one over the other, between cruise and run up, simply both.
As you correctly point out, no system is mature enough, and I include the systems from the competitors down southampton way in this, to be able to facilitate a cockpit display, however since one earlier correspondent ventured the question of whether HUMS should identify this type of thing, I merely wished to canvass / galvanise opinion that this subject, which has clear and present safety benefits, seems to have fallen by the wayside, possibly due to lack of interest from EASA. However, it is sufficiently matured to warrant seeing the project through to a third phase, and perhaps a more successful one at that.
However I have no wish to detract this thread from a spectacularly fine display from the crew.
On the subject of compressors, as you are aware, the offending frequency is easily identified as 1x or 2x etc from the Ng tacho or an MPU. However I'm not advocating one over the other, between cruise and run up, simply both.
As you correctly point out, no system is mature enough, and I include the systems from the competitors down southampton way in this, to be able to facilitate a cockpit display, however since one earlier correspondent ventured the question of whether HUMS should identify this type of thing, I merely wished to canvass / galvanise opinion that this subject, which has clear and present safety benefits, seems to have fallen by the wayside, possibly due to lack of interest from EASA. However, it is sufficiently matured to warrant seeing the project through to a third phase, and perhaps a more successful one at that.
However I have no wish to detract this thread from a spectacularly fine display from the crew.
Cyclic freezes a Bristow Thing?
It is not nice to be flying along and unable to move the cyclic, even if only intermittently.
The 76 was finally....after many occurrences....was cured by a thorough check of the rigging and controls which surfaced a mis-rigging and corrosion problem. Something along the lines of critical items being missed on inspection and overhaul as I recall.