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SO2 can produce substantial cooling. The above link shows the increase in SO2 production today compared to previous (selectable on right) As stated if you want 100% stay at home, lock the doors and probably die of inactivity and boredom. |
Going back to the ash density figures.. I was trying to estimate how much ash goes through an engine if you fly say 100km through a cloud at 0.2 miligrams per cubic meter... Suppose the intake is 1 meter in area and we just look at the swept volume... I make it about 1 x 100,000 x 0.2 x 10^-3 = 20Kg
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I have patiently explained about five times on this thread exactly what the problem with ash ingestion is :- extremely costly damage to engines.
It appears that there are some people who are too selfish or stupid to understand that exposure to ash risks ongoing engine maintenance problems that will make the dislocations caused by occasional airspace closures pale into insignificance. The only answer I can think of for these people is to buy your own aircraft if you wish to accept the risk of flying through ash clouds. |
Originally Posted by Sunfish
I have patiently explained about five times on this thread exactly what the problem with ash ingestion is :- extremely costly damage to engines.
Originally Posted by Sunfish
It appears that there are some people who are too selfish or stupid to understand...
I personally support Pace in this matter and I think what he says makes very good sense! Best regards, Sabenaboy |
I have patiently explained about five times on this thread exactly what the problem with ash ingestion is :- extremely costly damage to engines On what basis are you making such sweeping assumptions? Do you think the Airlines who are prepared to fly in low levels of ash pollution are also so stupid that they have not weighed up the potential engine damage costs (if infact they do get significant engine damage in their fleets) against the losses they would incur by as you put it "occasional airspace closures"? They have already operated in low level ash and to date I have not heard of significant damage. I am sure if there was they would be the first to ground their own fleets on a cost basis. I do not know what your background is to make such assumptions over what the airlines have decided to do with their own level of operational knowledge. I do not know long term what the costs will or will not be but I guess neither do you. It will not be our problem if you are right but I am sure the airlines will have weighed up all the risks and costs when deciding to operate in low level density ash. Pace |
Sunfish
The only answer I can think of for these people is to buy your own aircraft if you wish to accept the risk of flying through ash clouds. I am with Pace!:ok: |
peter we
Your problem seems to stem from a refusal to accept that when manufacture's say there is no safe level of ash ingestion, they mean it. The more ash, the higher the probability of damage, there is no 'safe' cut off level that you seek. The manufacturers have not stated that "there is no safe level of ash ingestion" The manufacturers can not tell you when it is unsafe to fly but can tell you when it is safe to fly. The zone between the two is subject to how you intend to operate in the nether region. The manufactures can only state that there is no known defined point of safe vs unsafe level and that therefore it is up to the variances of individual operations to establish safe operating procedures. (goes pretty much for other enviromental hazards as well, including birds and ice) Instead they advise a degree of avoidance of concentrations vs procedures to minimize impacts on the safety of a specific flight. What the operators are doing about costs is their business and not the business of naysayers in forums. |
Sweden is using an old military fighterjet from the 1950ies, Lansen (the lance) to collect ashsamples. Only two of them flying today, usually they´re
using them to collect radioactive samples. |
Sabenaboy:
Sunfish, could you enlighten us please and give us ONE example of an aircraft that had extremely costly damage to the engine, after flying through an ash cloud so thin that it wasn't noticeable to the eye! Just ONE example! PLEASE...!!! The National Aeronautics and Space Administration (NASA) DC-8 airborne sciences research airplane inadvertently flew through a diffuse volcanic ash cloud of the Mt. Hekla volcano in February 2000 during a flight from Edwards Air Force Base (Edwards, California) to Kiruna, Sweden. Although the ash plume was not visible to the flight crew, sensitive research experiments and instruments detected it. In-flight performance checks and postflight visual inspections revealed no damage to the airplane or engine first-stage fan blades; subsequent detailed examination of the engines revealed clogged turbine cooling air passages. The engines were removed and overhauled. This paper presents volcanic ash plume analysis, trajectory from satellites, analysis of ash particles collected in cabin air heat exchanger filters and removed from the engines, and data from onboard instruments and engine conditions. Even though this was a diffuse ash cloud, the exposure was long enough and engine temperatures were high enough that engine hot section blades and vanes were coated and cooling air passages were partially or completely blocked. The uncooled blades still performed aerodynamically but necessitated expensive overhauls. The insidious nature of this encounter and the resulting damage was such that engine trending did not reveal a problem, yet hot section parts may have begun to fail (through blade erosion) if flown another 100 hr. http://www.alpa.org/portals/alpa/vol...8AshDamage.pdf Why is it that some people have to put down others who have a different conviction or opinion??? That's how wars start! Can't you simply agree to disagree? Furthermore, the precautionary principle dictates that until we are totally certain about the levels of acceptable risk that we err on the side of caution. Pace: On what basis are you making such sweeping assumptions? Do you think the Airlines who are prepared to fly in low levels of ash pollution are also so stupid that they have not weighed up the potential engine damage costs (if infact they do get significant engine damage in their fleets) against the losses they would incur by as you put it "occasional airspace closures"? They have already operated in low level ash and to date I have not heard of significant damage. I am sure if there was they would be the first to ground their own fleets on a cost basis. I do not know what your background is to make such assumptions over what the airlines have decided to do with their own level of operational knowledge. I do not know long term what the costs will or will not be but I guess neither do you. It will not be our problem if you are right but I am sure the airlines will have weighed up all the risks and costs when deciding to operate in low level density ash. I'm not making any sweeping assumptions at all. Read the NASA report in full please. The basis of my comments are Five years(some time ago) as a Professional engineer in an airline maintenance department where one of my tasks involved the logistics of providing and positioning spare engines around the network. I also spent another Two years in an aerospace company that among other things assembled engines and made turbine blades and other componentry. While I am now well and truly out of that loop, I've visited and done business with both GE's civil and military engine people as well as Pratt and Whitney Canada and P&W at Hartford. The engineers at those places are not stupid. If they say no more than 2000 micrograms of ash per cubic metre that's good enough for me. As the NASA report states, the damage to the hot section is insidious and given the number of flights across the Atlantic an encounter with a large scale ash cloud by the Atlantic "fleet" could easily end up grounding hundreds of aircraft for engine changes. Given that the penalty for not grounding an aircraft for a few days will be weeks out of service, I'm not surprised that airlines are complying with the recommendations. Furthermore, the insidious nature of the damage alluded to in the NASA report means that you won't find out about it until it is too late As for costs, and having done entire airline engineering maintenance budgets for Five years, I can safely say that the cost of pulling and overhauling engines at intervals far less than their expected time in service plus the out of service time for aircraft caused by the inevitable backlog of engine work, will dwarf the costs of grounding an aircraft until the danger is past. I'm sorry is these facts are unpalatable to you but that's it. |
Sunfish
Firstly thanks for giving us your qualifications in making a statement. I cannot speak for SabenaBoy but would imagine his posting referred to the present situation? Regarding the DC8 incident this was at NIGHT and as such the crew were unaware of what they had flown into or the density of what they had flown into. This incident was a long time ago. There was a period of 65 flying hours before damage was found and the initial inspections just after the incident showed NO damage. This incident is not a good example because of the uncertainties. We were talking about flight in very low ash concentrations ie the new guidline levels. There is NOTHING in this report to state that the flight was in conditions which met the new guidline levels but levels which were far higher. In that context I cannot see how you are using this old example in any way as proof of your arguement that flights made to the new density levels will lead to massive increases in maintenance costs. Most of us are already aware that dense ash with high engine temperatures can cause engine damage. Pace |
Key problem is the precision of the data!
OK - chances are that 2000 micrograms is low enough not to be a problem for that particular flight. But what about the variation in ash density that the aircraft actually encounters? It might be lower or marginally higher than the magic 2000. Also there's the question of cumulative exposures and what that does to projected remaining on-wing life. |
Here it comes again
Sorry to be the bearer of potentially bad news, but......
Iceland volcano to emit large new cloud: meteorologists An Icelandic volcano which caused havoc to European aviation after erupting last month is to emit a large new ash cloud after surging back to life, meteorologists said Thursday. A plume of ash measuring up to seven kilometers (more than four miles) high had been detected at the Eyjafjoll volcano, said a statement from the Icelandic Met Office and Institute of Earth Science. "The eruption has changed back to an explosive eruption, lava has stopped flowing and most of the magma gets scattered due to explosions in the crater," said the statement in English. "The ash plume rises high above the crater (4-7 km) and considerable ash fall can be expected in wind direction. No signs of the eruption ending soon." Breitbart.com LoboTx - geologist at-large |
Again, this link, provided earlier, is as good as any. The earlier series of this site had no ash above FL200; here, there are now substantial volumes of ash from FL200 to FL350. Flew to the West Coast of Canada from the UK today and we routed LHR - Land's End then turned north about 40W for Western Canada. Now I can see why.
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THe NASA DC 8 incident: Please... Not again!
@Sunfish:
I should have known, that you would be coming back with that NASA DC8 case. You obviously haven't read the thread thoroughly and certainly not my own post #2486. Allow me to post this information again. Read page 11 of the report you linked to: The flight crew noted no change in cockpit readings, no St. Elmo’s fire, no odor or smoke, and no change in engine instruments. They did notice that no stars were visible, but this is typical of flight through high cirrus clouds. After seven minutes the crew noticed that the stars had reappeared, and at about this time the scientists reported that the research instrument readings had returned to normal. There was still no change in engine or airplane instrument readings. When the stars reappeared, the readings returned to normal. This would suggest to me that no visible ashes, also means that no significant ash concentrations are likely to be present or even measurable. So what would I suggest? Restrict flying into the black areas of the ash concentrations charts to daylight VMC conditions. By "flying VMC" I mean that you can fly through a thin layer of low level stratus or a typical nice-weather cumulus or a thin layer of nicely white cirrus or cirrostratus. Flight through thick layers of nimbostratus would NOT be wise, as it would be able to obscure otherwise visible ash clouds. And of course any layer of visible ash -so even a slightly discoloured layer- would be an absolute NO-NO! Furthermore research A/C AND military A/C (with post flight inspections!) should be out there NOW over the ocean flying in the black areas, to collect VALID scientific data on flying through measurable ash concentrations. Why? Because, looking at these ash concentration charts it's clear that it's only a matter of time until the whole UK and Western-Europe gets covered again by such a black area. So collect data NOW on flying through these areas. And then if these test flights show evidence of damage, well then so be it. We will then KNOW that there is a risk. Until proven otherwise I will continue to believe that flying in clear blue skies in invisible ash concentrations will not cause any direct danger to the flight or any severe damage to the airframe and engines. Conclusion: the challenge is still on: Give us ONE example of an aircraft that had extremely costly damage to the engine, after flying through an ash cloud so thin that it wasn't noticeable to the eye! Just ONE example! PLEASE...!!! Best regards, Sabenaboy |
PJ - I hope you enjoyed your brief stop-over.
Those charts are daunting. It looks as if N Atlantic traffic is in for a very difficult time. Looks like you just made it back. I think my motto at the moment is 'ETOPS - no thanks!' Add the latest reported volcanic activity................ We need to do a rain dance in the UK I think - not normally a problem. |
The stated reason why the track of the NASA DC-8 blundered into the ash (which was part of a cloud well-known to the VAAC) was that it was 'old' so that the ash particles had become ice-coated. The satellite imagery therefore mis-identified it as normal cirrus. So: had the flight been in daylight, there would be another question. What would the pilots have actually seen above them, 'obscuring the stars', or around them? Brownish ash or whitish cirrus? You tell me! After this length of time, I doubt there's any daytime visual evidence of what the cloud looked like at the point where the incident occurred but there might not have been much to indicate 'Here be Ash'! |
Off topic, but just for the record re the above:
As stated if you want 100% stay at home, lock the doors and probably die of inactivity and boredom. |
Is it affecting ops on europe-usa crossings at the moment?
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BOAC's mention of ETOPS has caused me to wonder:
If Keflavik is closed (I'm not sure if it has, so far) or if it can only be approached from the West, will this impact ETOPS operations? |
British Airways News, 6th May
Since British airspace reopened BA has inspected each aircraft before every flight and the company has carried out airframe and engine inspections on 23 aircraft.
These have included internal inspections of the engines based on guidance from the engine manufacturers looking for any evidence of a build-up of volcanic ash. Filters from the oil and fuel system were removed and sent away for scientific analysis for any volcanic trace elements, while a detailed inspection of the airframe was carried out looking for typical signs of erosion and build up of any debris within air conditioning and other aircraft systems. “Working with other airlines across Europe we have completed sample inspections on an additional 24 engines as part of a programme agreed with the enginemanufacturers,” said quality services manager Keith Rose. “All of our inspections to date, plus in excess of 2,000 engineering walk rounds checks, have not found any confirmed indications of volcanic ash. “Indeed samples taken from the exhausts of a number of engines have been analysed by specialists at Bristol University and found to contain no traces of ash whatsoever. Since resumption of our operation last week we have flown over 27,000 flying hours and 6500 sectors with no confirmed ash events The above statement is copied from today's issue of the BA company newspaper. |
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