Engineers - any sign of ash damage so far?
 

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?

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:

My cup of tea seemed to have a rather powdery taste up at FL350 today.........perhaps thats was just for insulting the crew though?? :}

To make a long story short:
NO

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.

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

Looks like the flight ban through the ash cloud worked!

As above..

correct Intruder
 

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..

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:}

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

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:

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.

your not making sense how can sulphur get into a sealed oil system?????????

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:

Hi, You may want to read up on Labyrinth seals.
Rgds

I guess the spotter in the name gives it away.:ugh:

You obviously don't that's why I suggested you read up on them. :=

See SHUNT knows. :ok:

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.

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

sorry i forgot spannersatcx , as a spotter im not welcome on the "professionals" forums my mistake :ugh::ugh::ugh: get over yourself

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:

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.....................

Ash in pressurised oil system?
 

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.

Smudgethecat.
 

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.

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.

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 ?

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?

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.

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.

Are there any partial oil loss or total oil loss engines still in use?

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

Still quite a few Darts in service, worldwide.
A really fine engine.

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

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:

AB. But it does. As Smudge said -

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.

Thats pretty much exactly what we found ...........................absolutely nothing.

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 :)

Engineers - any sign of ash damage so far?
 

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?

I've learned so much from this thread:)

411A

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