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Agaricus bisporus
23rd Apr 2010, 12:17
To all you engineers out there, have you seen any physical sign of damage to engines/airframes/systems following the recent volcanic ash event in Europe?

smudgethecat
23rd Apr 2010, 12:21
Up to now no signs of any problems we are also checking the oil system scavange and px filters and the fuel LP filters for contamination, so far so good:ok:

BUGS/BEARINGS/BOXES
23rd Apr 2010, 21:49
My cup of tea seemed to have a rather powdery taste up at FL350 today.........perhaps thats was just for insulting the crew though?? :}

IFixPlanes
24th Apr 2010, 00:18
...have you seen any physical sign of damage to engines/airframes/systems following the recent volcanic ash event in Europe?...To make a long story short:
NO

Piper19
24th Apr 2010, 01:46
A captain came to me this week that he smelled something. F/O did not however. We investigated, some grey dust in ram air exhausts, but I think most of it is already there for years. All our aircraft have the same grey layer, also the ones that didn't fly in the cloud. We began to see things just because you pay attention to them. So I guess no damage till now.
In Oostende an MD11 was grounded, news reports said because of ash found in engines. However a collegue in Oostende told me they grounded it in waiting for a borescope. I suspect this comes out to be nothing found.

mcdhu
24th Apr 2010, 09:17
Had a brief chat with out chief engineer yesterday - no signs of ash in a very comprehensive monitoring program including boro inspections.

Europe wide network - CFM

Intruder
24th Apr 2010, 10:31
Looks like the flight ban through the ash cloud worked!

Bruce Wayne
24th Apr 2010, 13:50
Looks like the flight ban through the ash cloud worked!


As above..


All our aircraft have the same grey layer, also the ones that didn't fly in the cloud.

falconer1
24th Apr 2010, 14:06
Looks like the flight ban through the ash cloud worked!

And the final bill for maybe starting one or two days early to resume full flight ops will only be known to the beancounters of the airlines once they start comparing engine maintenance bills for the two years from now, with those from the last two years..

gavthespotter
24th Apr 2010, 15:02
Smudge, so why waste time money checking oil filters how could ash ever get into a sealed oil system doesnt make sense unless some one left the cap off that is:}

spannersatcx
24th Apr 2010, 17:39
how could ash ever get into a sealed oil system

Because they are not sealed, read up on basic turbine engines.:eek:

gavthespotter
24th Apr 2010, 20:05
dont come all high and mighty with me mate i know how plane engines work and i dont see how ash can get in a oil system if ash can get in then oil can get out ..right:suspect:

brooksjg
24th Apr 2010, 20:16
Maybe not 'ash' in the oil.

But reports after volcanic ash encounters (eg. the NASA DC-8 Incident in 2000) include references to very high levels of SULPHUR in the oil. This was taken as a confirmation that the aircraft had indeed gone through an ash plume. Sensors that happened to be on the aircraft also recorded high levels of SO2 in the outside air - so that's the route by which the sulphur gets into the oil.

gavthespotter
24th Apr 2010, 20:18
your not making sense how can sulphur get into a sealed oil system?????????

Pugilistic Animus
24th Apr 2010, 20:23
Read what the cool dude:cool: Spannersatcx says

hint: a spanner is the British term for 'Wrench' and Cx has a few planes on hand:rolleyes:

SHUNT
24th Apr 2010, 20:30
Hi, You may want to read up on Labyrinth seals.
Rgds

spannersatcx
24th Apr 2010, 21:01
I guess the spotter in the name gives it away.:ugh:

i know how plane engines work You obviously don't that's why I suggested you read up on them. :=

See SHUNT knows. :ok:

Mr @ Spotty M
24th Apr 2010, 21:20
Yet again we have some excellent posts from spannersatcx.:ok:
Which is why the engine manufactures are telling airlines to check oil filters for ash contamination.
This is why my company is sampling some engines across its fleets at reduced intervals, this to be on the safe side.

Biggles78
24th Apr 2010, 21:27
Just Googled Labyrinth seals. I had seen them before but had no idea what they were called (sort of seems obvious now). :O It is sort of a closed system that is open. A Labyrinth seal is an oxymoron.
Thanks guys for todays education. :D

gavthespotter
24th Apr 2010, 21:49
sorry i forgot spannersatcx , as a spotter im not welcome on the "professionals" forums my mistake :ugh::ugh::ugh: get over yourself

smudgethecat
24th Apr 2010, 22:03
Gavthespotter, gas turbine engines employ labyrinth seals which rely on air tapped of the compressors to function ,this air actually enters the bearing sumps therefore any contaminants which are in that air will possibly enter the engine oil system, hence the reason for checking the filters ,now be a good chap and get off back to the spotters forum:ok:

BOAC
24th Apr 2010, 22:57
A crippling set of first 7 posts..............................

The world has really gone mad - we've got a spotter on 'Airlines, Airports' asking about a g/a at BHX and some sort of 'Secret Service' war going on on the Polish 154 thread.

Now, about the British General Election.....................

Landroger
25th Apr 2010, 00:00
I have to admit, it is pretty counterintuitive that any one atmosphere contaminant can get into a pressurised lubrication system. What is the average sort of pressure in an aeroplane engine (high bypass fan jet)? A modern car is between 60 and 100 psi.

Having said that, I am an MRI engineer and our magnet cryogen recombinant systems work at about 4 psi. Given that Helium is the second smallest atom in the periodic table, it can leak through pretty much anything - outwards. However, magnets have personalities and some of them have an amazing propensity to suck atmospheric pressure air into them.

How do we know its there? Because various electrical ports that we need to use from time to time, become blocked with ice, but don't go thinking its just plain old frozen water. Oh dear me no. The water vapour freezes out long before it gets very far into the magnet. No, the ice we are talking about is where air (per se) has somehow got past 'O' rings into a 4 psi over ambient environment and the oxygen has condensed out, dripped about a foot deeper into the magnet and hit a metal surface somewhere where it freezes solid. Ever seen frozen oxygen? Its blue.

Can anyone actually explain how any ambient pressure contaminant can get into otherwise sealed, pressurised systems?

Roger.

Landroger
25th Apr 2010, 00:08
Gavthespotter, gas turbine engines employ labyrinth seals which rely on air tapped of the compressors to function ,this air actually enters the bearing sumps therefore any contaminants which are in that air will possibly enter the engine oil system, hence the reason for checking the filters ,now be a good chap and get off back to the spotters forumhttp://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif


A little harsh Smudge, I feel. I am not an aero engineer and I didn't know that - see my post above - but I was still interested. Now I know, I won't trouble you again. Want to ask me about 30,000 Gauss magnetic fields? Careful, I might give a short sharp answer, because you ought to know. :)

Those of us on this forum may not be aircraft engineers, but we are engineers and we are interested. Bask in the knowledge that others are asking you the question. :ok:

Roger.

lomapaseo
25th Apr 2010, 00:51
People that ask to learn get answers. People that ask questions and then disparage the answer get put down as trolls. There is enough knowlege on PPRune for a reasonable balanced explanation to come out among multiple posters without retorts.

john_tullamarine
25th Apr 2010, 01:57
I don't think that one needs to add anything much to the previous post by lomapaseo.

For those who see the need to wave their arms and froth a bit at the mouth .. all you succeed in achieving is making a bit of a fool of yourself.

The knowledge base in PPRuNe varies from the highly expert to the abjectly ignorant but, even then, we all can learn a bit from each other. Many of our aeronautical new chums are, of course, knowledgeable or highly expert in other, unrelated, fields.

A touch of humility all around goes a long way in such an environment I suggest ?

spannersatcx
25th Apr 2010, 09:45
gav" i know how plane engines work" the spotter, anybody is welcome on these forums, no laws against it.

My knowledge is limited, I only have 32 years experience in aviation maintenance, and I don't pretend to know it all as that would be dangerous, and I don't pretent to know what Landroger is talking about, but I would respect his knowledge in his field.

There are ways to ask questions and to take that information to learn from it, unfortunately the abrupt and agressive attitude that is shown by some posters doesn't do them any favours. I'll help anybody glean knowledge I don't have a problem with that, that's how we all learn, and if I don't know something I will ask that's how I learn.

I could show you some pics taken during a borescope inspection (you know what that is don't you?) the other day from a CF6-80 as fitted to a 747-400 after a suspected ingestion of something, we also had to replace the oil system scavenge filter and drain, flush and replace the engine oil, I wasn't sure what was ingested by the engines, but made the call to ground the a/c and carry out the necessary checks, really pissing off the 450 pax that had been waiting for 4 days to fly, but hey what do I know.

By the way the check is the same if ingestion is volcanic ash or sand, so prey tell why do I have to drop the engine oil and filters on a gas turbine engine as fitted to the 744?

mad_jock
25th Apr 2010, 10:12
Can anyone actually explain how any ambient pressure contaminant can get into otherwise sealed, pressurised systems?

Theory alert could be bollocks.

Surface tentsion allows fluids to do some very strange things when in capillarys liquified gases are famous for it. They will allow fluid to travel uphill so to speak.

My theory is that they have a slight leak and there is Oxygen fluid forming, if it manges to bridge the hole the surface tension will start doing its work and cappilary action will work pulling it up stream. Now because the fluid will be travelling into a cooler temp it will aid heat transfer to the outside it will cause even more oxygen to become liquid and supply the capilary action. Once its inside if there is any sort of height difference between top and bottom of the seal you will have started a syphon. Liquid oxygen being relatively heavy compared to He will have no probs overcoming the 4 psi differential. And thus you have an up hill (in pressure differential terms) leak. Look on the bright side though it means your not loosing highly expensive He through a seal leak.

lomapaseo
25th Apr 2010, 11:31
Can anyone actually explain how any ambient pressure contaminant can get into otherwise sealed, pressurised systems?

I never did quite understand what this question was about, so my answer may be missing the mark.

For starters the oil system is not sealed from outside air. It does have a scavenge just like your car engine. It does rely on knife edge seals as well as friction carbon seals. It does not only provide bearing lubrication but also adjusts the thrust load on the bearings via air pressure internally to the gas path.

For the thrust load balance as well as cooling of hot metal parts behind the combustor, pressurized air is drawn off the gas path (typically in the high pressure compressor rotor). This air can entrain dirt and this dirt can flow through the labryinth seals between the oil system and the internal pressurize cavity of the rotors. Note you want any air flow to come out the breather rather than oil flow inside a hot rotor compartment.

FE Hoppy
25th Apr 2010, 13:13
Are there any partial oil loss or total oil loss engines still in use?

411A
25th Apr 2010, 14:37
gavthespotter
Probationary PPRuNer
Join Date: Apr 2010
Location: formby
Age: 25
Posts: 7

Look at the stated age.
About says it all, really...a youngun' who thinks he knows it all.:rolleyes:

Are there any partial oil loss or total oil loss engines still in use?
Still quite a few Darts in service, worldwide.
A really fine engine.

barit1
25th Apr 2010, 16:06
Can anyone actually explain how any ambient pressure contaminant can get into otherwise sealed, pressurised systems?


Think about it. Where do you think the pressurizing air comes from? Have you studied how the sump sealing system really works?

Here's a good introduction (http://www.exxonmobil.com/lubes/exxonmobil/emal/files/TTopic14_JetEng2.pdf)

Agaricus bisporus
25th Apr 2010, 16:32
Mods, please close this thread if it doesn't come back onto topic.
I asked a topical question that had nothing to do with odd behaviour in gas capilliary action or labyrinth seals.

:ugh:

forget
25th Apr 2010, 17:15
AB. I asked a topical question that had nothing to do with odd behaviour in gas capilliary action or labyrinth seals.

But it does. As Smudge said - gas turbine engines employ labyrinth seals which rely on air tapped of the compressors to function ,this air actually enters the bearing sumps therefore any contaminants which are in that air will possibly enter the engine oil system,

L337
25th Apr 2010, 17:43
I am reluctant to copy from the BA company forum, but I think on balance it helps clear up some of what is being discussed, and shows what a "major" carried out prior to the ban being lifted. The post relates directly to the test flight BA carried out in a 744.

All the filters in the aircraft were replaced before the flight. After the flight, they were all removed and sent for analysis - the theory being that any contamination of the filters could only have occurred on that flight. Nothing was found. Fuel and oil samples were also taken and they came back clean too. The engines were boroscoped and showed no evidence of any damage or accumulations of ash deposits. The airframe (including windows) was examined for any signs of abrasion - none was found. The QAR and FDR data was sent for analysis to detremine is there was any abrormal relationship between engine parameters (eg erroneous EGT for the N1) or air data parameters (eg Angle of Attack incompatible with IAS) - again nothing has been found.

The aircraft was deliberately flown in areas where the Met Office Model showed that ash encounters were likely, but outside the areas where the WSI model showed ash encounters were likely (you might like imagine these areas as being similar in principle to the Enhanced Procedures Zone and the No-Fly Zone respectively, which the CAA has mandated in FODCOM 12/2010 )

fflyingdog
25th Apr 2010, 18:19
Thats pretty much exactly what we found ...........................absolutely nothing.

lomapaseo
25th Apr 2010, 19:13
Mods, please close this thread if it doesn't come back onto topic.
I asked a topical question that had nothing to do with odd behaviour in gas capilliary action or labyrinth seals.


You could always try steering the thread to something more specific to your interests by asking more questions that somebody might have an answer

Looks like this technical discussion is of more interest to the participants.

Of course a Mod could always change/merge the thead title to something more generic, where a variety of similar questions to yours might be asked :)

Niallo
25th Apr 2010, 20:10
I too support a return to the original question.
Presumably current jet engines are highly instrumented and these readings are recorded for later analysis.
I expect that airline engineers and engine manufacturers are now routinely analysing the recorded engine operating data from all their flights to identify any change in trends pre and post ash exposure.
Have they noticed any changes?

Pugilistic Animus
25th Apr 2010, 20:24
I've learned so much from this thread:)

ZQA297/30
25th Apr 2010, 20:43
411A
Are there any partial oil loss or total oil loss engines still in use?
Still quite a few Darts in service, worldwide.
A really fine engine.


Its been thirty-odd years, but I am pretty sure the RR Dart was not a total or partial loss system.
I think you may be mixing it up with the Viper as fitted to Jet Provost, and some earlier powerplants.
Re; Dart
Within its limits (cycles) it was a simple and dependable powerplant

411A
25th Apr 2010, 21:02
I think you may be mixing it up with the Viper as fitted to Jet Provost, and some earlier powerplants.


Could be, however, it was described as such in our F.27 course at Fokker, many many years ago.
RR Viper, also used on the early models of the HS.125...also a fine aircraft/engine combo, although just a tad...noisey.:}

Landroger
25th Apr 2010, 23:01
First of all, slightly off topic - bear with me Agaricus Bisporus - but I refer to Mad Jock;


Theory alert could be bollocks.

Surface tentsion allows fluids to do some very strange things when in capillarys liquified gases are famous for it. They will allow fluid to travel uphill so to speak.

My theory is that they have a slight leak and there is Oxygen fluid forming, if it manges to bridge the hole the surface tension will start doing its work and cappilary action will work pulling it up stream. Now because the fluid will be travelling into a cooler temp it will aid heat transfer to the outside it will cause even more oxygen to become liquid and supply the capilary action. Once its inside if there is any sort of height difference between top and bottom of the seal you will have started a syphon. Liquid oxygen being relatively heavy compared to He will have no probs overcoming the 4 psi differential. And thus you have an up hill (in pressure differential terms) leak. Look on the bright side though it means your not loosing highly expensive He through a seal leak.

My sincerest thanks for that Jock, because in my eighteen years as an MRI engineer (33 as CT eng) nobody, including all our support engineers and factory Service Engineering types, have ever come up with any more than a half ar8ed answer to that particular conundrum. Particularly when there is almost never any water ice in there - only Oxygen ice. You sir, I believe, have it exactly. Thank you again - I will be offering it to my colleagues who, I trust, will think I am truly the dog's bo11ocks. :):D

Right, back on thread; Agaricus Bisporus asked;

Mods, please close this thread if it doesn't come back onto topic.
I asked a topical question that had nothing to do with odd behaviour in gas capilliary action or labyrinth seals.




Which I thought a bit disingenuous as Forget then reminded us;

But it does. As Smudge said -
Quote:

gas turbine engines employ labyrinth seals which rely on air tapped of the compressors to function ,this air actually enters the bearing sumps therefore any contaminants which are in that air will possibly enter the engine oil system,


Which I suspect held the nugget there, entirely cogent to the overall question - to which L337 posted the answer.

I know a lot of people, all engineers or interested in engineering, who were absolutely gagging to know what you BA Aero Engineers found when you got your hands on that 744 at Cardiff. Like others, I had thought the flight was a bit of a PR stunt, but when I learned that the short hop to Cardiff had taken some three and a half hours and stepped all the way up to 40,000ft, I began to suspect that Willie Walsh was going to be standing next to you when you carried out your checks.

Thank you for that L337. :)

Roger.

mad_jock
26th Apr 2010, 08:28
Nae Bother landrodger suprised one of your RPA's didn't spot it.

I can even suggest a method of sealing against it which might cut down your HE getting through seals so quick.

If you get your seal and put a water shroud over the top of it and fill it will distilled 100% H2O then freeze it down either using system temp or expanding gas over it. Then bring your system down to temp. The Ice will be denser than your seal so the He should take longer to get through it. And the interface where the cappilary action takes place will not have any air near it to form liquid O2. Vibration may be a problem breaking the seal between ice and surface but it could help out with some of the seals. If you can figure out a way of getting pressurised ice eg blue glacier ice with no O2 in it even better.

PS take all the glory for yourself, and do a patent search before you mention it to any one. Could be a nice boost to your pension. And in my child hood and to this day I don't think of MRI, it was and always will be NMR.

brooksjg
26th Apr 2010, 09:34
errr - since one of my postings got caught in some diversions about plane-spotting, MRI, liquid Helium, etc. could I please also request a return to the original topic!

Ok - we now have some evidence that the BA 'test' / PR flight that ended up at Cardiff having meandered around some 'ash-containing' bits of sky did not ACTUALLY have a significant 'ash encounter'. Great - Willy Walsh was in no serious danger after all!:)

Doesn't make any difference to a REALLY basic question: IF (probably WHEN) volcanic ash becomes a problem in N Europe again, what reliable measures exist to measure the extent of ash encounters soon after they happen? Visual external inspection is OK if there's something to see. Don't rely of flight crew reports: frequently, there will have been nothing to report, from inside or outside the aircraft.

So the answer is there are NO effective measures. Does that make you guys on the firing line happy? Well, it shouldn't. Remember particularly ash damage MUST be cumulative and that aircraft utilisation is often on reciprocal routes, repeated ad nauseam.

mad_jock
26th Apr 2010, 10:10
Sorry maybe a mod could spin the MRI stuff off into another thread.

As a pilot I agree the topic is a very important one to aviation.

lomapaseo
26th Apr 2010, 10:57
Remember particularly ash damage MUST be cumulative and that aircraft utilisation is often on reciprocal routes, repeated ad nauseam.

Something wrong with that argument

The data does not support it.

john_tullamarine
26th Apr 2010, 12:47
Moderating threads ....

Just so folks have a handle on my philosophy .. in general I try not to interfere with a thread as whatever I do it is always a case of "you can please some of the people some of the time and none of the people all of the time" so I get shot whether I leave it or edit it ...

The only time I tend to jump in is if anyone starts to get nasty etc., or if a thread goes so far off the rails ...

In fact, I think one of the great things about PPRuNe is the range of digressions which crop up in threads .. ?

avionic type
26th Apr 2010, 12:57
As a BA pensioner I hope W.W. looked at the fine print of the insurance policy before his trip, the cost of a 747-400 could have put a dent in our liquidity .
Joking apart I bet a lot of midnight oil was burnt before it was decided to make the trips and was not a rush of blood to the head on his part .
[Thinks!! was the plane going to Cardiff for o/h anyway?].Cynic.
P/S I'm NOT a Plane spotter though still interested in the techie and flying side.:hmm::hmm:

Pugilistic Animus
26th Apr 2010, 18:56
......for a linearly variable magnetic field considering only the z direction for now,.....
the water protons in the body will be resonant at vl =gamma/2pi (B0 + GzZ).....:8

with NMR it is possible to go below absolute zero :ooh:

ESR is nice

and

NOESY knows everything


:} could not resist:}

kitwe
26th Apr 2010, 20:29
411A is correct. The RAF still flies the Dominie T1 with RR Vipers that have a total loss oil system.

Landroger
26th Apr 2010, 20:56
Total loss engine oil system
411A is correct. The RAF still flies the Dominie T1 with RR Vipers that have a total loss oil system.


Rootes type superchargers were completre loss lubricated. := Not many people know that. :)

Roger.

brooksjg
26th Apr 2010, 23:03
The data does not support it.
Support what? Repeated trips on the same route(s) by the same aircraft?
or ash damage inside turbine hot sections being cumulative?

Thinking of the situation where fine-grained VA gets into the cooling channels inside turbine blades and / or forms a glassy coating on blades or stator vanes, therefore blocking leading-edge or other cooling holes, what's actually going to remove it? Therefore, further ash encounters must result in accumulation in the same area(s). If not, why not?

punkalouver
27th Apr 2010, 02:51
Perhaps not designed as a partial loss oil system for the Dart, but there was always planty of oil in the wheelwell area of the 748. Always did like the sound when spoolingup. Once it was started, it wasn't so great.

dubh12000
27th Apr 2010, 19:49
Thinking of the situation where fine-grained VA gets into the cooling channels inside turbine blades and / or forms a glassy coating on blades or stator vanes, therefore blocking leading-edge or other cooling holes, what's actually going to remove it? Therefore, further ash encounters must result in accumulation in the same area(s). If not, why not?

I think you are dead right. It wouldn't suprise me at all if there are incidents of blade shrouds departing the back end or vane trailing edges disappearing due to a very slow deposition rate of ash deposits inside the components.

lomapaseo
27th Apr 2010, 21:07
Thinking of the situation where fine-grained VA gets into the cooling channels inside turbine blades and / or forms a glassy coating on blades or stator vanes, therefore blocking leading-edge or other cooling holes, what's actually going to remove it? Therefore, further ash encounters must result in accumulation in the same area(s). If not, why not?

I think you are dead right. It wouldn't suprise me at all if there are incidents of blade shrouds departing the back end or vane trailing edges disappearing due to a very slow deposition rate of ash deposits inside the components.

Just to add some balance to this. I believe that the glass deposits will flake off with engine thermal cycles (takeoffs and shutdowns) and that any deposits in the cooling air holes will eventually work they way out over time. The cooling air is an open system depending on flow pressure where the air comes in at some compressor station, picks up the heat in the front end of the turbine and then flows back out into the turbine gas path. Meanwhile the reduced, by ash, holes will cause the metal temeprature to rise and the metal will begin to ablate away (like ice melting) over many engine takeoff cycles. It's typical for this process to be seen by borescope inspection but if left unchecked over will lead to lowered EGT margin on hot day takeoffs and reduced in-service life.

In other words history will be repeated in the numerous events from Mt Pinatuba as documented in the

Thomas Casavadell report

Casadevall (http://pubs.usgs.gov/pinatubo/casa/index.html)

Now what was the question again? :)

dubh12000
27th Apr 2010, 21:27
Just to add some balance to this. I believe that the glass deposits will flake off with engine thermal cycles (takeoffs and shutdowns) and that any deposits in the cooling air holes will eventually work they way out over time.

Not from my experience Lomapaseo. External deposits will be fine as you say, but a couple of blocked dust holes on a blade tip and away she goes. Yes you will pick up the vane damage easier on a boro, but you will still have to open to do anything about it. I'm thinking CFM56-5 HPT vane and LP Vane 1 off the top of my head.

lomapaseo
28th Apr 2010, 00:16
Not from my experience Lomapaseo. External deposits will be fine as you say, but a couple of blocked dust holes on a blade tip and away she goes.

Any volcanic ash data that shows this? I don't recall a rash of incidents like this in the Pinatuba referenced data base above. I'm not saying that damage won't happen, but will the pilot have to shutdown engines? or is it only a maintenance finding on the ground?

Brian Abraham
28th Apr 2010, 02:17
Here is a technical report on the engine damage on a DC-8 (CFM engines) operated by NASA after encountering a diffuse volcanic ash cloud. The encounter lasted for a period of seven minutes, was at night, and had it not been for the scientific instrumentation on board the aircraft no one would have been aware the event had taken place. Please note it was estimated the turbine blades may have had as little as 100 hours of life remaining as a result of damage incurred.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030068344_2003079762.pdf

dubh12000
28th Apr 2010, 07:05
I'm not saying that damage won't happen, but will the pilot have to shutdown engines? or is it only a maintenance finding on the ground?

Unlikely the pilot would shutdown to be fair.

That report shows the HPT blade (the blade in the photo has been through a repair cycle already). It would have been interesting to also see a fillet cut on the blade, you will normally see a lot of accumillation in the serpentine passages in the airflow "deadzones". It would have also been nice the see the LPT blade 1, which is a shrouded blade with an interlock.

LeadSled
28th Apr 2010, 08:17
411A,
on the early models of the HS.125...also a fine aircraft/engine combo
You speak in jest, of course!

Only aeroplane I have flown that weathercocks out of wind.

Remember the CAGS??

We discovered some really weird characteristics of that Viper, including a ability to surge and only recover to a low power "false idle", with no response to thrust lever movement. One ( not VH-, but ex-VH-) went into the drink near Nice with that problem.

The undercarriage downlock system could only have been designed by Heath Robinson!! Hence the big block of faired hardwood down the guts, and the extended flap hinges with little wear pads, and DCA AU got to prove it worked, Avalon 1965 or '66, from memory.

But the rear main bearing lubrication was total loss, and we did learn to keep very careful track of the minimum oil consumption.

Tootle pip!!

safewing
28th Apr 2010, 10:15
Does anyone know has the improvement in engine technology over the years diminished the risk of volcanic ash?

Are there any recent VA incidents with newer technology engines? Has improvements to seals, lubrication methods, filtering and bleed management either by design or consequence improved the situation over the BA Indonesia or KLM Alaska events?

One must assume that volcanic ash exist globally though in minute concentrations at location far from the origin. Does a regular well diciplined maintenance program catch these events and categorise them as for example component x replaced due to normal or abnormal wear and tear or will the new measure reduce maintenance interval inspections times to cater for the apparent increase in abrasive particulate damage?

mad_jock
28th Apr 2010, 10:47
I would have thought that nearly all advancements will have led to engines being more at risk from ash encounters.

As you design for effeciency the tolerences get smaller and smaller. Anything which distorts or alters the system will have greater and great effect on the over all system.

Car engines are an example and old carb low pressure ratio engine could take serious abuse. Timing belt goes stick another one in set the timing and carry on. Modern high pressure ratio engine timing belt goes you have bent valves cam shaft replaced seals blown and it has to go into the workshop to get the electronics sorted out.

Pax1987
28th Apr 2010, 12:28
Hi everyone !

Iíve been following the debate on the other thread, but I thought that my question would be more accurate here. Before I ask my question, I would just like to stress that I am not involved in this industry, Iím just a passenger who got interested in this volcanic ash issue. I have no knowledge whatsoever about jet engines.
The topic of this thread being possible ash damages found on aircrafts, Iím surprised that no one has mentioned this event here? Curiously, it has only been related in the Italian press as far as I know. Hereís a link, and basically it says that an Air Berlin Boeing was allegedly found with ash in its engines, and the plane was therefore grounded in Olbia. The Italian press says this has to be confirmed, but no one did it. Does anyone here know something about it? For your information, this happened on the 19th or 20th of April.
Olbia: cenere vulcanica nei motori di un Boeing 737 Air Berlin - Servizi e Approfondimenti | Notizie turismo, News e cronache internazionali | Master Viaggi (http://www.masterviaggi.it/news/categoria_news/39417-olbia_cenere_vulcanica_nei_motori_di_un_boeing_737_air_berli n.php)
Thanks!
PS: I hope I'm welcome although I'm not a professional :)

brooksjg
30th Apr 2010, 08:42
Unfortunately, no details AT ALL of what was found where. Pity. If the incident occurred around the suggested dates, then there was presumably ash around in sufficient quantity to create problems, especially on the northern part of the routenear Cologne. Other question, of course, is where the aircraft had been on immediately preceding flights....although I doubt that anything would have been missed at Cologne with the 'heightened awareness' (aka panic) at the time.

Anyone know more / can track details of this particular flight and aircraft?

bugdriver
1st May 2010, 15:32
Concerning the high amounts of sulphur found in the oil of the NASA DC-8, what damage can high sulphur content in the engine oil cause? I have tried searching but can find no source for information on this.

Bug

dubh12000
1st May 2010, 16:11
Over time you will have sulphidation of any of the nickel based blades / vanes, but I think you would have to have prolonged exposure.

Do a web search on type 1 and type 2 sulphidation.

bugdriver
1st May 2010, 19:57
dubh12000

Thank you for that, it lead me to some good reading on sulphidation in a salt rich environment (marine), but all I can find is what it does to the turbine and compressor blades in the gas stream of the engine.

I am trying to find out whether high sulphur content in the lubricating oils is a concern or not, as found in the engine oil of the NASA DC-8.

mono
2nd May 2010, 23:06
High sulpher content in the oil is not a danger but an indicator.

It help to identify that an ash encounter has occurred, hence the checks. If it is high (yet the crew have not reported an encounter) then the AMM CH 5 ash encounter inspection must be carried out.

brooksjg
3rd May 2010, 08:36
then the AMM CH 5 ash encounter inspection must be carried out
Please excuse my ignorance....
Is this a general convention or the rule applied to one (or a few) type(s) of aircraft?

Mr @ Spotty M
3rd May 2010, 08:47
You will find a Ash inspection in all Airbus and would guess Boeing a/c, l only say guess with Boeing as l am not sure on the early types.

IFixPlanes
3rd May 2010, 10:44
B737-100/200 AMM 05-51-261
B737-300/400/500 AMM 05-51-57
B737-600 to 900 AMM 05-51-31
B747-100 to 800 AMM 05-51-35
B757 to 777 AMM 05-51-31
MD-11 AMM 05-58-02
Airbus (All) AMM 05-51-25

spannersatcx
3rd May 2010, 13:51
brooksjg chapter 5 of the maintenance manual gives conditional inspections for numerous things that may be encountered, these conditional inspections include amongst others, inspections to be carried out after A lightning strike, hard landing, overweight landing, encounter with volcanic ash OR sand etc etc.

These inspections ask you to look at certain areas and do certain tests, if you find any evidence then a further more detailed inspection may be required.

brooksjg
3rd May 2010, 16:05
maintenance manual gives conditional inspections for numerous things that may be encountered,Suspected as much but do not have immediate access to chapter & verse on multiple A/C types.

Do all the extra checks in AMM Chap 5 (or wherever they crop up on different types) depend on physical evidence of ash found on / in parts of the aircraft? Or do they say things like: 'If high sulphur levels are found in engine oil AND the aircraft may have had a volcanic ash encounter, you MUST borescope the hot section of the affected turbine'?

It still seems to me from other information that there's unwise dependence on definite visual evidence before assuming the worst about less-accessible parts such as inside the turbine. Checks on filters on engine bleeds seems a sure-fire test for actual ash exposure, leading to a QUANTITATIVE result after weighing and/or microscopic examination of washings from the filter(s). Finding ash on a surface somewhere or high sulphur in the oil will remain only QUALITATIVE tests, indicating more checks need to be done...

WenWe
3rd May 2010, 16:43
You keep banging on about checking filters on engine bleeds.

Mind enlightening us what they're fitted to/where & what they look like, as apart form older types that use coalescer bags in the aircon packs or ozone converters before the packs on newer aircraft - there aren't any that I know of.

ssc1
3rd May 2010, 16:47
Anyway after all that ,at a certain large airline we have not really found any ash deposits ,just salt deposits of which volcanic ash does not have in it ,i have that from a very reliable source ..but as for stopping flying over the six day period ,i think it was the right decision ,better to be safe than sorry ...we seem to have stopped doing the extra inspections now as no ash present ....and i may be new on here but i'm not that new to the industry ,some 35 years i think swinging spanners

brooksjg
4th May 2010, 00:47
You keep banging on about checking filters on engine bleeds.
Mind enlightening us

The NASA report on the DC-8 incident stated specifically that ash was found in the filters of the cabin AC heat exchangers. (The filters were changed at Kiruna on the assumption that ash WOULD be trapped but actual examination apparently waited until after the aircraft got back to Edwards AFB.)

I assumed (incorrectly??) that if the DC-8 design required such filters, they'd be fitted on later aircraft too.

brooksjg
4th May 2010, 00:54
BBC Radio 4 'Report' programme aired Monday 2000 provided a good summary of the Ash Story So Far, with interviews with some of the key players from CAA, NATS, etc.

No mention, however, of any organised attempt or directive about what examination of aircraft should be done post-flight.

Assuming ash damage is cumulative and ash forecasting still depends on modelling. Any available quantitative data could be used to forecast the impact on specific engines and also to calibrate the ash forecasting model.

I'd hoped that evidence from aircraft that MIGHT have had an ash encounter would be considered valuable enough to be collected in an organised way. But it seems not.

spannersatcx
4th May 2010, 08:13
No mention, however, of any organised attempt or directive about what examination of aircraft should be done post-flight.

There is a check c/o on every a/c after every flight, this check encompasses many things, it is issued or endorsed by the a/c manufacturer and the regulating authority. If you did or do it you will know. :)

brooksjg
4th May 2010, 09:46
I was referring specifically to checks for volcanic ash.
Although Mark 1 Eyeball checks on pitot heads etc. and accessible surfaces where ash MIGHT collect are obviously part of what is done anyway, there is plenty of evidence (quoted here and nearby ad nauseam) that negative external visual checks do NOT necessarily correspond to what's actually happened to the inside of engines, in particular the turbine hot section. Please correct me if I'm wrong, but borescoping at least one engine on EVERY potentially-affected aircraft whilst parked at the ramp is not a viable option.

And what about cumulative data? Obviously, the same aircraft will fly multiple routes during a Volcanic Ash alert. OK - so it passes the visual checks every time with flying colours. But there MAY have been multiple undetected ash encounters, each one contributing to the total accumulation sitting in the turbine cooling system

And what about all the OTHER aircraft from other operators that will fly the same route?

If, as an expert in the area of ash checking and engine maintenance planning, you're totally happy with the existing checks and tests, fair enough.

KUMOOZ
4th May 2010, 13:38
Re Spanners last post,

As an ex engineer and now driver it is noteworthy and perhaps worth mentioning in the distant past, a post/preflight inspection was always carried out by an Engineer, regardless of where the flight terminated/began on the planet.
In the interest of cost saving some pre/post flight inspections are now carried out by flight crew, no less diligently I am sure but perhaps not as qualified to spot something amiss. I would say particularly new pilots with low experience.
I am not aware of any specific training given to pilots to cover this issue.....swiss cheese?

just a thought.

spannersatcx
4th May 2010, 13:46
KUMOOZ, depends where you are I suppose, but we do them on all ours and those that we handle.

TURIN
4th May 2010, 13:48
There is a check c/o on every a/c after every flight, this check encompasses many things, it is issued or endorsed by the a/c manufacturer and the regulating authority. If you did or do it you will know.

Problem is that some airlines are fully endorsing the manufacturers recomendations and others are not.

Two spring to mind, no names etc.


Similar a/c type.

Airline 1. The check is drawn up by the airline's maint engineers and involves a separate check sheet. L/G doors open, flaps extended and a thorough inspection signed off in the tech log.
Airline 2. No extra paperwork, transit check unchanged, no communication from the airline's maint engineers regarding any extra detailed checks required.

KUMOOZ
4th May 2010, 14:14
Spanners,

RE-assuring to hear.....I flew 10 years with tcx and all transit checks outside of the UK (etops excepted) were always carried out by the flight crew..are you telling me tcx and other carriers are now having the aircraft checked by engineers each and every transit during the present times......at ZTH? DLM? PVK?................... really??????

Mr @ Spotty M
4th May 2010, 16:52
l think he is not referring to your airline (TCX), only his own set up.:ok:

spannersatcx
4th May 2010, 17:05
Airline no2, one that we probably used to do!!, not the best communicators, Pain In the Ar$e no doubt.

Sorry KUMOOZ CX not TCX.

Genghis the Engineer
4th May 2010, 18:46
Does anyone know has the improvement in engine technology over the years diminished the risk of volcanic ash?



I was told yes the other day by a design engineer at Rolls Royce. What he told me is that because civil and military technology tend to shadow each other a lot, there was a lot done after the 1991 Gulf War lessons in engine resistance to sand, that has mapped to volcanic ash resistance in civil gas turbine engines.

He was senior and experienced enough that I'm inclined to believe he knew what he was talking about.

G

TURIN
4th May 2010, 19:16
Airline no2, one that we probably used to do!!, not the best communicators, Pain In the Ar$e no doubt.


Close, but no.

I'll say no more. :suspect:

lomapaseo
4th May 2010, 20:32
safewing

Does anyone know has the improvement in engine technology over the years diminished the risk of volcanic ash?


The improvements in tolerance to rain-hail and/or ice would significantly improve the resistance to Volcanic ash.

However, the most significant improvement is knowledge of what to do if you enter volcanic ash and develop symptoms, i.e. cut back on the operating temperature until the symptoms clear.

It's like telling a a victim of a breathing problem and in a coughing fit from inhaling pollen, dust, etc., to take smaller breaths until the coughing subsides,

Once again, the safety issue is the individual event of entering a cloud and developing sysmptoms and a proper reaction.

The rest of the equation having to do with on-the-ground actions is a operator maintenance issue, which is more of the business that they know best how to address. Costly yes, but dispatching unsafe planes is not likely to be more than an umeasurable blip.

Pugilistic Animus
4th May 2010, 21:37
My question is is it possible for contaminants i.e silicates to flow into the hot metal compressor blade materials during subsequent cooling thereby creating brittle points?

:)

WojtekSz
4th May 2010, 23:16
spannersatcx, TURIN:

simple SAFETY question:

why do not clearly state which airlines are too much relaxed on maintenance? i would make sure not to book my tickets with them! Those which follow the prescribed procedures surely deserve more pax to cover extra costs ;)

GarageYears
10th May 2010, 17:19
BBC News - Ryanair admits volcanic ash in Belfast engines (http://news.bbc.co.uk/2/hi/uk_news/northern_ireland/8672663.stm)

So, to all the naysayers this stuff does exist and it goes in the big round things that suck in tonnes of air and burns it up.

Note that Ryanair initially denied this entirely.

According to the report these aircraft had flown in airspace that was "open and unrestricted".

This made me chuckle: "The spokesman said Ryanair cannot explain why there was ash in the engines other than there are trace elements of it in the atmosphere." Well, duh! There's this honking great big volcano barfing up huge plumes of stuff - all along it has been stated that this stuff is not necessarily visible to be harmful.

I suspect this is the tip of the iceberg.

For now all I expect is a series of replies denying this is really a problem, etc.

I'm half expecting a "wrong-kind-of-air" excuse, bit like the "wrong-kind-of-leaves" excuse that British Rail use every few years or so, when all the trains stop running in Autumn.

- GY

falconer1
10th May 2010, 17:45
I suspect this is the tip of the iceberg.

you bet, and the show will not be over until the old lady ( or better said, that young juvenile delinquent volcano) stops singing..

it is the smallest tip of the iceberg..

but all airlines who advocated flying through that sh... so loudly are keeping silent...

why is that?

well they are so cash strapped and so badly managed and very soon they will need lots of money for unscheduled maintenance and "early overhauls"..

they will ask that money from the EU taxpayers...but not under the title of "engine maintenance", but lost biz due to that volcano etc etc etc..

so before we EU taxpayers will hand out tons of money to these clowns we should ask some smart beancounters to check these airlines' balance sheets...to find why they really need so much dough...

maybe hidden somewhere under "performance restoration" on the engine maintenance side of their books

brooksjg
11th May 2010, 00:45
I'm half expecting a "wrong-kind-of-air" excuse, bit like the "wrong-kind-of-leaves" excuse that British Rail use every few years or so,

Even more apposite was the Wrong Kind of Snow excuse, also by British Rail, when unexpectedly fine snow got drawn into the cooling system of some locos in northern England. The snow promptly melted and shorted out the electrical system. Ironically, we then have the MUCH more recent classic example of failure to read history - by Eurostar. You'll remember that various Eurostars stalled in the Channel Tunnel, when snow / ice that had got into the locos crossing France melted in the (warm) tunnel and, guess what?, shorted the electrics.

Clearly, volcanoes have been around for a while and VA has presumably been a (potential) problem for turbines since they took over from propellors! Quite shameful, really, that proper research and development effort starts only after a major incident.

TURIN
11th May 2010, 01:03
spannersatcx, TURIN:

simple SAFETY question:

why do not clearly state which airlines are too much relaxed on maintenance?

Because we want to keep our jobs. :ok:

im1234
21st May 2010, 15:57
WSJ - BA: Found No Ash in Engines (http://online.wsj.com/article/SB10001424052748704852004575257891213419312.html?mod=WSJEURO PE_hps_sections_business)

BA has operated more than 20,000 flight segments and conducted more than 8,000 engine inspections, Mr. Walsh said. "Not only have we not found any damage from ash, we have not found any ash"

Graybeard
24th May 2010, 06:52
I hesitate to post this one, as I receive so many emails with legit pix, but bogus stories about them.

"Hereís what happens to an engine when it's flown through a volcanic ash cloud. This is a Cessna Citation Jet (CJ2) out of Germany a few weeks ago. Luckily the other engine kept running, although very sluggishly***"


Following were several pix of an engine with uncontained failure, apparently N1 or N2 blades shed.


Sorry, I don't have a way to post the pix, nor inclination to find a public site to do it.

GB

forget
24th May 2010, 09:00
I hesitate to post this one

Pity you didn't extend the hestitation ad infinitum. :ugh:

PBL
24th May 2010, 09:39
Graybeard,

the following short note from the NTSB, CEN10RA135 (http://www.ntsb.gov/ntsb/brief2.asp?ev_id=20100302X25146&ntsbno=CEN10RA135&akey=1) , says that an aircraft from Eisele Flugdienst GmbH, D-IEFA, suffered an uncontained "event" on March 1.

The citation came from forget (which citation I overlooked) and repeated by infrequentflyer789 on the R&N ash thread, in answer to my query.

I found two paint schemes from Eisele in pictures on the WWW, and one paint scheme fits the pictures I was inquiring about, to which you may also be referring. The registration in those pictures is a D-reg.

March 1 is before the volcanic ash started causing problems.

PBL

TURIN
24th May 2010, 11:00
Yup, it's a hoax email.

Snopes (http://www.snopes.com/photos/airplane/volcanicash.asp)

Graybeard
24th May 2010, 14:36
Thanks, guys. Should have checked Snopes myself.

I still haven't figured out why people pull this crap. Just last week I received the one again about a guy from New York retiring in Portugal, and finding the large barn on his new farm was full of collector cars.

Hmm, looked like they could have been covered with volcanic ash...

GB

forget
24th May 2010, 14:49
I still haven't figured out why people pull this crap.

Simple. They rely on idle individuals to send world-wide without a ten second web check. Actually, a common sense check takes less that that.

lomapaseo
25th May 2010, 00:27
Simple. They rely on idle individuals to send world-wide without a ten second web check. Actually, a common sense check takes less that that.

Agree.

I have pictures of volcanic ash damage as well as sand ingestion damage (there is a difference) but I'm darn sure in todays environment that the half-experts who troll web sites would take them out of context and spew them throughout the web in order to support their own expertise among the ignorant.

Just once I saw what can happen when one of my photos was taken out of context and ended up on Snopes ... hopefully never again.

Fargoo
29th May 2010, 17:06
This is the sort of fallout to be worried about :eek:

Last pic on the slideshow

BBC News - In pictures: Volcanos erupt in Ecuador and Guatemala (http://news.bbc.co.uk/1/hi/world/latin_america/10189244.stm)