Quantas A 380 Incident – again

 

A very few words from R-R

Four days ago I concluded that there had been an oil fire in the incident on 4 November. I had not seen the press release of the previous day, Monday 8 November 2010. This is an extract.

“… Rolls-Royce has made progress in understanding the cause of the engine failure on the Trent 900 powered A380 Qantas flight QF32 on 4 November 2010. It is now clear this incident is specific to the Trent 900 engine.

As a result, a series of checks and inspections has been agreed with Airbus, with operators of the Trent 900 powered A380 and with the airworthiness authorities. These are being progressively completed which is allowing a resumption of operation of aircraft in full compliance with all safety standards. We are working in close cooperation with Airbus, our customers and the authorities, and as always safety remains our highest priority.

The Trent 900 incident is the first of its kind to occur on a large civil Rolls-Royce engine since 1994. Since then Rolls-Royce has accumulated 142 million hours of flight on Trent and RB211 engines.  …”

See   http://www.rolls-royce.com/civil/news/2010/101108_trent_900_statement.jsp

Then there was another press release yesterday, 12 November 2010 and this is an extract which is the only engineering statement.

“….  Immediately following this incident a regime of engine checks was introduced on the Trent 900s to understand the cause and to ensure safe operation. These have been conducted in parallel with a rigorous examination of all available evidence, including data from the damaged engine and its monitoring system, analysis of recovered material and interrogation of the fleet history.

These investigations have led Rolls-Royce to draw two key conclusions. First, as previously announced, the issue is specific to the Trent 900. Second, the failure was confined to a specific component in the turbine area of the engine. This caused an oil fire, which led to the release of the intermediate pressure turbine disc. 

Safety continues to be Rolls-Royce’s highest priority.”

See  http://www.rolls-royce.com/investors/news/2010/121110_interim_mgt_statement.jsp

Now those will be – I expect, the only and last words from the engineers to the general public.

Oil fires are a great fear of aircraft engineers. The oil is a more or less flammable liquid that is being pumped throughout the internals of the engine even close to the hottest parts. Here the failure of some component has resulted in the oil fire.  The engineers probably had to look at and rule out or rule in over a hundred possible causes. As it is confined to the Trent 900 it seems less likely to have been an elastomeric oil seal than a failure of some component that contained oil. RR have said above that the fire ‘led to the release of the intermediate pressure turbine disc’

The word ‘release’ seems to be a very carefully chosen word that is, perhaps intentionally, slightly vague. The consequent fire may have destroyed and ‘released’ the highly stressed turbine disc into fragments. These could have burst centrifugally out of the engine and might have damaged the rest of the aircraft.

I think that there is a more likely alternative. That would have been the fire destroying by overheating the connection between the turbine and the compressor that it was driving. This could have resulted in relatively few fragments if any.

Quantas A380 Incident – My rethink

A few days ago I said, “I wonder if the failure is to the engine cowling or by-pass ductiong rather than to the engine core.”

I have seen a better photograph in the papers since then showing more detail. In this the rear end of the engine core still shows little structural damage. However the rear of the outer cowling structures that normally enclose this part have disappeared. The remaining forward cowling shows what appears to be smoke or oil stains and its rear edge has an incredibly shredded appearance.

I now think that large parts of the aft core cowl or thrust reverser, if it has one, has been consumed by fire. Except that si from any part that fell to earth. Engineers know that metals can actually burn if immersed in oxygen. Whether that has happened in this incident I do not know. for although the aircraft was travelling at high speed with the chance of ‘fanning’ any flames, it was also at high altitude with relatively little air and thus oxygen to burn.

It seems to me now a more likely possibility that there was an oil leak, perhaps in the bypass duct or intercase, that was ignited by the high temperature part of the engine. This, presumably, was not or could not be extinguished by the activation of on-board fire extinguishers.

The Rolls-Royce development engineers in Derby and in the Singapore Maintenance Base will still be working busily to pore over components; explain and calculate the cause; and the design engineers to design out any likelihood of this incident ever happening again with the Trent 900 engine.

I have to say that my guesses are based upon laughably sketchy evidence. The Rolls-Royce, Quantas and Singapore Airlines engineers will have volumes of data and evidence to think about and act upon. I am afraid, though, that they will not be telling the media much about it any time soon.

BP Deepwater Horizon Gulf Oil Spill

 WHAT WAS NOT THE CAUSE?

The CAUSE of the BP Deepwater Horizon Mexican Gulf oil spill was neither the engineers drilling below the ocean in itself nor the deep drilling in itself. 

The matter of the BP Deepwater Horizon Mexican Gulf oil spill has popped its head once more above the parapet in the prints; albeit with a much reduced prominence. It is now, you see, old news. It may have been considered to be important once: indeed it verged on the hysterical. Apparent importance as measured in the media though surely drains away merely with the passage of time if there is no new ‘shock horror’ or, worse, if the matter seems to resolve itself or even improve.

One reason for the return is that another report with important provenance [the US President’s Commission – see below for link] has supported the BP claim that the failings of BP were not the only causes of the accident. Another is because in this quarter, BP has returned to profit. But, let’s be honest, neither of these aspects are terribly sexy news topics

I have to confess that, as an engineer, I knew very little about the technology of drilling for oil.  I have to note that I am not connected to BP in any way. However, engineers can learn an enormous amount about a technology from the reports that appear in the sad wake of an accident. So it was, with the BP Deepwater Horizon Mexican Gulf oil spill. It was, undoubtedly, an extremely serious accident, killing 11 people and injuring 17  of the Rig crew, with the enormously widespread and expensive [to a vast number of innocent parties] consequences.

Everything that follows is an enormous simplification but not, as far as I can manage, greatly in error. I cannot give full details of the technology here, one, because I am far from an expert and, two, because I cannot spare at least 193 pages as in the preliminary BP report. However I will try to give a flavour of the difficulties and successes [and, in this case, failures!] of the engineers.

The technology used is quite remarkable and unlike, as far as I can see, any other engineering. In simplified terms, this is what the drilling engineers do as a matter of routine.

The engineers will drive down to a depth of three and a half miles below the surface of the ocean – not more or less – but precisely. The first part of this is to reach down to the sea bed that is itself about a mile down. Then they make a hole in the sea bed that varies in diameter from around 36 ins to around 7 ins. This hole is clad on the inside with joined up lengths of steel tube as they go deeper. Clearly, the tubes have to be somewhat smaller than the hole in order to pass down but, in order for them to be able to last for years; they have to be completely in contact with the surrounding rock. So what do the engineers do? They fill the gap at the outside diameter of the tubing with concrete. 

From the bottom of the hole upwards! 

The drilling engineers have to pump into the bottom exactly the right amount of concrete to fill the gap between the outside diameter of the tube and the hole in the rock. So they have to measure the tube clearance in the rock hole over the whole two and a half miles and calculate the volume of concrete required. And what varieties of concrete! There can be dozens of different mixes to perform properly in the different down-hole environments and to fulfil many different tasks.

When the drill hole reaches the correct depth, which is that of the oil-bearing stratum, they face another problem. A angry, heavy liquid is just bursting to surge unstoppably up the drilled hole. The crude oil is driven thus at nearly 12 000psi by a combination of artesian pressure and pressures due to dissolved gases. Similar problems face the engineers sometimes at some other strata in between

How do they stop the crude oil from thundering up the new opening to the surface that the oil has not known for some millions of years? Basically they fill the hole with a liquid that is heavier that the oil: this is what is called ‘mud’. A column of mud 3.5 miles high is enough to keep the oil down by overcoming the oil pressure.

Having arrived at this depth, the engineers have a string of tubes 3 5 miles long joined together. This string they now have to turn into a good pressure vessel that will withstand considerable pressures of around the 12 000psi. This staggering pressure can be both from the outside trying to get in but also, in other circumstances, from the inside trying to get out. Having managed to do that, by the way, the engineers have to find tests that will prove that the pressure tightness is good. No mean task in itself and highly significant it turns out.

The oil drilling engineers have always been very aware of the risks associated with the extraction of oil from the bowels of the earth. This has been in the forefront of their minds ever since the gusher became a strange symbol of oil industry success [through failure!] at least since the 1900’s. Even then they were recognised as a waste of money and a great risk to health of the drillers and damage to the equipment and the environment. From this came the first ‘blow-out preventers’.

The modern Blow Out Preventer, BOP is an enormously large complex and expensive piece of kit. Its purpose is to protect the well and the drillers and their equipment by providing several different ways of sealing the drill hole in greater or lesser emergencies. The several elaborate systems of pipe work, electrical power, electronic controls and pressure vessels make it a massive structure. It is so large and elaborate that I will not be able to say much about it here. I hope to investigate and return to discuss it further in a later posting. 

The BOP is meant to operate either on instructions from the surface drilling vessel or even, in dire emergency, automatically. That was the plan anyway.

The only effect of depth might have been that deciding on the correct mud pressures and concrete mix may have been affected by the pressures at such a great depth may have been affected by the well known exaggerated effect of the difference of two large numbers. But, compared to the other events, this is definitely a second order effect.

A Foreword to the report says many things, but it seems to be necessary to quote part of it as follows:

This is the report of an internal BP incident investigation team. The report does not represent the views of any individual or entity other than the investigation team. The investigation team has produced the report exclusively for and at the request of BP in accordance with its Terms of Reference

The Executive Summary says the following. It is rather wordy but I do not want to try to précis it and run the risk of misinterpretation.

The team did not identify any single action or inaction that caused this accident. Rather, a complex and interlinked series of mechanical failures, human judgments, engineering design, operational implementation and team interfaces came together to allow the initiation and escalation of the accident. Multiple companies, work teams and circumstances were involved over time.

The BP Deepwater Horizon Gulf oil spill tells us so many things about the struggles of the engineers working on the needs of the world in the late Twentieth Century and the early Twenty First. None of the things that it tells us say that drilling below the ocean or drilling deep should be stopped because it is too dangerous.

Then if neither the depth nor the undersea were the cause, what was? See Part 2.

References and links

This is the BP website giving links to their initial Report in different media and at different amounts of detail.

http://www.bp.com/sectiongenericarticle.do?categoryId=9034902&contentId=7064891

An equally important website below is that of the US government Commission studying the accident and offshore drilling in general. This is a vital [in every sense of the word] resource that, at the time of writing is live. I was listening to part of one of the hearings streaming live with sound and slides this afternoon.

http://www.oilspillcommission.gov/

This is formally the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling. Its tasks are, firstly, to examine the facts and circumstances to determine the cause of the Deepwater Horizon Oil Disaster; secondly, to develop options for guarding against future oil spills associated with offshore drilling; and, finally, to submit a final public report to the President with its findings within 6 months of the Commission’s first meeting

You can find general oil drilling information below

http://en.wikipedia.org/wiki/Oil_drilling

This also is a good general description of the drilling process

http://www.oilprimer.com/oil-well-drilling.html

Some websites describing drilling jargon can be found at ‘Rigzone’

http://www.rigzone.com/training/

Also consider Schlumberger.

http://www.glossary.oilfield.slb.com/

Quantas A380 incident

I wonder if the failure is to the engine cowling or by-pass ductiong rather than to the engine core.
The only photo that I have seen in the media showed little obvious damage to the engine core. The cowling is something like a car travelling on the road having its bonnet [hood to the Americans] or wing tear off.
If it was so, this would be sort of good but bad. Sort of good because any damage caused by failure of the core structure or rotatives is likely to be much more difficult than a cowling failure of sheet or fasteners to put right. But still bad because any – any – failure in flight is intensely dangerous. to the aircraft, the passengers and the reputation of Rolls-Royce or Airbus. Easy for me to speculate.
I know that the design and development engineers will have been scrambling for a couple of days to put matters right.

A startling nugget

In the contemporary, media world it seems as though iPhone apps are the Gold Standard of achievement.

An article in the 31 October 2010, Sunday Times, Business Section, p8 told us about the ‘PayPal tycoon’ who was pouring millions of dollars into the Tesla electric sports car. I am not sure whether it was he, Elon Musk or the reporter, Mark Harris, [with the proud by-line of Silicon Valley] who originated the essential insight.

It was that “…. building cars turned out to be a lot trickier than writing software.

There is nothing to add to this other than that it makes a good place to start this blog

The Engineer as Rock God

Isambard Kingdom Brunel was, without any doubt, a Rock God.

He may well have flourished way back in Hanoverian England before there were too many others: but, nonetheless, he showed all the genius and charisma of the modern celebrity. More than that, though, he possessed a thoroughly practical genius and drive. He  designed tunnels, bridges, complete railway lines, and an ocean-going ship that was decades before its time. But he not only designed them but, and this is a much more difficult skill, he brought them into being. What is even more remarkable, almost every one of his projects is still in existence and functioning.

He was what today we would call a dreamer. The internet and the country’s bedrooms are filled with those. He was not only that though. He dreamed dreams but also brought them into reality in the teeth of the cynical smiles of the money men, politicians and the press of his day.

Nearest modern equivalent to Isambard Kingdom Brunel that I can think of is Steve Jobs of Apple, begetter of the I-Pod, I-Phone and the I-Pad. It is not a very close analogy but Isambard certainly had the same towering self-esteem as Jobs and without that one cannot achieve gigantic projects. Perhaps someone can suggest a closer modern successor.

 However, the paramount virtue of Isambard in my eyes is that he was an engineer. His undying reputation lies in that he was one of the first and, arguably, the greatest engineer in modern history.

Today’s engineer still has the same task to do: she wrestles with the problems that are making the life of human beings inconvenient and overcomes them. He or she engages with the myriad, protean forces of the natural world: subduing them or bending them to the contemporary advantage.

Some decades back, the Journal  of the professional Institution, The Institution of the Mechanical Engineers was the ‘Chartered Mechanical Engineer’ [ as the CME, it was then the mechanical engineer’s equivalent of the New Musical Express]. It frequently published letters bitterly whining, firstly, about the lack of visibility of, and respect for, mechanical engineers in the wide world. They further complained secondly, that if engineers were ever referred to, it was only as if they always and only grasped spanners and wore the uniform of oily overalls with ‘Loser’ stencilled on the back.

Perhaps it is not the same these days.

When I look at some of the other topics that are pored over in great detail on the internet and their depth of discussion, I think that I see that there is an engineering-shaped hole. I  hope that I will be able to spin a few strands and webs across the hole. Then perhaps they will gleam enough to attract a few interested readers.

This blog is that of an engineer looking about and noting the outlines of the engineering processes that form the skeleton passing throughout and supporting the modern world.

Its blog looks in three directions.

1.Some indications of what engineering is about for those who may wonder whether it is a career for them.

2.Contemporary events from an engineer’s perspective.

3.As a little light relief [or maybe only a boring drone] scattered through will be nuggets of information on the starting and working in engineering in the second half of the Twentieth Century.

Let’s rock……..smartening up the presentation as we go along!

Of course, Wikipedia has something to say, respect, about Isambard Kingdom Brunel.

 http://en.wikipedia.org/wiki/Isambard_Kingdom_Brunel

Some, though, say that the best ‘Life’ of Brunel is still that of L T C Rolt,

 http://www.amazon.co.uk/Isambard-Kingdom-Brunel-L-T-C-Rolt/dp/0140117520/ref=sr_1_4?s=books&ie=UTF8&qid=1287261933&sr=1-4

You will find the Institute of mechanical Engineers on the internet at

http://www.imeche.org/home

And the journal is

http://www.profeng.com/  Calls itself the home of professional engineering on the web.