Qantas grounds A380s after Singapore emergency landing

Originally posted by sy.gunson
It's a very difficult proposition to re-engine an aircraft. Cammacorp did so with the DC-8 but had to redesign the engine pylons and have these certified at huge expense.

The reason I asked the question about switching over to the UAE engines is because they must already have a certified configuration.

Also the electical and fuel supply systems may need reconfiguration.

It would be cheaper to render the modular exchange of turbine sections unlawful and require total engine overhauls in lieu of removing modules.

That makes sense. I never thought it would be cheap to re-engine it, just less time consuming than engineering a new engine from scratch.

Yes Singapore and Lufthansa are the other two airlines that use the Rolls Royce engine, though I read they have a lower maximum thrust compared to the Qantas.

Rolls Royce plans to replace roughly half the engines, apparently?

Rolls-Royce to replace 40 A380 engines: Qantas www.khaleejtimes.com.../international/2010/November/international_November891.xml§ion=international&col=

If the thinning oil pipe and stress fracture is related to a known manufacturing defect, maybe they know how to avoid the defect on the replacement engines?

reply to post by Arbitrageur


Re-engineing IS a big deal.

But, if money were to be "no object", then it can always be accomplished. Heck, there were even conversions to upgrade the old Boeing 727 to a two-person cockpit configuration...but, didn't find much market, for various reasons. COST, EPA (and other ICAO noise abatement requirements, etc). The engines, again. Noisy. Polluters.

Plus, airframes don't last forever, only so many cycles. And, airplane manufacturers make more profits by selling new stuff.....leasing companies form up, and place huge orders, and operators snap them up in leasing arrangements, better tax breaks, etc....long list. Ah, the dynamics of marketing.....

Arb....when you are looking into an airline, and which engine/airframe combination they choose, when they place orders (on new models, when they expand their fleets) you have to look at what they have traditionally flown previously. Corporations like to have a certain "compatibility" in their fleets, and choose engines based on that, mostly. It can be because of some component parts interchangeability, even between different P/W models of engines, or GE, or R/R....to something as simple as the oil. One manufacturer may specify a different brand, or viscosity, of oil.....and airlines buy up a lot of the stuff, and don't want to stockpile DOUBLE, if they don't have to, just to supply the "mixed bag" of engine makers they operate.

When American bought TWA, for instance.....the B-757s that TWA had in the fleet (a handful) had the Pratt/Whitney engines, while American had opted for the R/R. So, those jets were returned to lessors, sold, etc....to get taken out of the fleet. It is not only a maintenance concern, but pilots, training, flight manuals, "differences" to keep track of...

...I know this from hard experience, at my airline. We had a mixture of 727s, (and DC-10s) at one point....the 727 AFMs were HORRIBLE! We had white, pink, green pages, and entire systems sections in those colors, that were specific to a fleet number range....you had to KNOW which machine you were on, and refer to the correct color for reference...THEN, the "temporary" pages were yellow....and were inserted, and deleted...as instructed, based on dates....a mess!!!!

The FAA (back in the 1980s, I'm talking here) turned a "blind eye", counting on our expertise, and skill, as aviators....but, now things are alot more stringent. Major "differences" within an airline's fleet of "same" model airplanes? Cheaper for the companies, nowadays, to standardize the hardware, rather than "Band-Aid" it with paperwork, like they used to.....

Sorry about my little trip down memory lane.....

Here's a good resource website to research airlines, fleets, and the engines they operate, with specifics about ALL of their airplanes. Has a WorldWide database: www.airfleets.net...

Here is the link direct to the alphabetical airline search page:

www.airfleets.net...

You can browse around, search their resources.....

reply to post by weedwhacker
Thanks for the links and the explanation, weedwhacker. The maintenance issue makes perfect sense. I've worked in numerous factories that buy machines and likewise part interchangeability and standardization is a big maintenance issue there as well.

I guess my biggest question now is how Rolls Royce is going to manage those 40 engines they replace? Maybe they'll rebuild them and eliminate the manufacturing defect in the rebuild process? I have a hard time imagining them just selling the metal for scrap.

And the other half of the engines they DON'T replace, I wonder how confident I should feel about flying on a plane with one of those? I need to get a better feel for how easy or difficult this manufacturing defect is to identify, details still seem sketchy at this point.

Ok a few things here need addressing,

A modular design turbofan is not a problem at all, the advantages well and truly outweigh any perceived disadvantages. In fact in the roughly 35 years of RB-211 ops it's proven to be an exceptionally reliable method. Given that the Trent 900 series is nothing more than a member of this extended family of triple spool motors, it shouldn't be seen as suffering some fundamental problem because of this as many millions of hours of fault free RB-211 ops have been flown, and many thousands of overhauls and module changes performed without incident. The problem here looks to be nothing more than a badly manufactured oil line whether by manufacture, design or both at this stage hasn't been revealed but rest assured it is being resolved. As someone who has worked on these powerplants (including the one that failed) as well as earlier models of Roller I must say they are a revelation in how well an engine can be designed to be so easy to maintain. Early model 211's could be an absolute pig to work on particularly if it was anything inside the cold stream duct/inter-services panels area. There is nothing funny about doing a shutoff valve change on a hot summer night in the back of a hot engine. However the Trent 900 doesn't suffer from issues like that and given that teething problems affect all engines no body should be reaching for the panic buttons. There is no need to "design out" as it was put, the modular nature of the Trent/RB-211 family or any other engine design that uses this philosophy for that matter, nor any need to ban it's use. It would most certainly NOT be cheaper to go down this path it will cost significantly more and given that the different modules have different service life limits, extremely wasteful.

On another point, yes re-engining can be an expensive proposition but if the benefits outweigh the costs airlines will do it. Qantas itself has on several occasions done this with its early model 707-138's coming to mind, and only a handful of years after they entered service. However unless something disastrously wrong and insurmountable to design out crops up there will be little to no prospect of switching to the competitor engine for QF, SIA etc.

As for the issue of commonality of engine types and manufacturers being an influence on purchase choice it depends. Often there is enough difference between members of a family of engine that it really isn't that much of an advantage at all. I know from our experience that we have operated 3 major versions of RB-211 (not including the Trent 900) two major variants of the CF-6 plus several sub variants, two different types of CFM 56 and more JT-9's than I could count. Even on single airframe types we have had for example on the 747 over the last nearly 40 years the JT-9 family, the RB-211 family and the CF-6 family and usually operating concurrently. So what it shows is that at the end of the day an airline will look to BOTH what it's experience is with as well as what a new engine design can bring, logistics does come into it but sometimes not as much as you might think or what the salesmen will try to sell you on.

LEE.

reply to post by Arbitrageur


Yeah to you or me that would seem a perfectly logical thing to replace the Trent engines with different ones but there are so many technical bureaucratic hurdles that frankly, if the exchange of disc modules is creting the problem, then the fastest solution is to prevent module exchanges.

That loads up the cost of airline maintenance.

By the way I loved the 727 and the Vaslan conversion with more modern P&W JT8D-207/209 engines was a great idea come too late. Incidentally they never changed the centre engine because that was too complicated and expensive.

The Tay re-engined 727-100Q did have the centre engine replaced but that called for a larger inlet duct so the entire aircraft needed substantial rebuilding.

When you re-engine the aircraft must be re-certified for stall speeds, runway distances, weights etc. It could conceivably require the A380 re-engining recertified as an entirely new hybrid type.

It does not automatically follow that you can use the certification for the other factory fitted version as weights may differ and other basic systems may differ too.

reply to post by thebozeian


I certainly agree that it would be more expensive to design out the modularity however indications are pointing to the conclusion that this was behind seal leaks.

If the flanged seal which was identified as the cause is redesigned, then only time will tell if that is a band aid solution. stuffing a bigger seal in the same hole and performing a borescope check for pooled oil at every turn around would in my opinion be a band aid solution.

RR took a conscious choice with the RB-211/Trent to head down that path of modularity for the perceived benefits. Sometimes being different can bite back.

Ultimately insurance companies will decide the survival of RR trent engines

Originally posted by sy.gunson
I certainly agree that it would be more expensive to design out the modularity however indications are pointing to the conclusion that this was behind seal leaks.

No there are ZERO indications pointing to engine modularity being behind the failure.

Anyone suggesting otherwise are either misinformed or have ulterior motives.

Originally posted by sy.gunson
If the flanged seal which was identified as the cause is redesigned, then only time will tell if that is a band aid solution.

What seal? It was a failure of a counter-bored pipe due to mis-alignment of the counter bore!

Someone lined up the drill wrong, or the methods guys screwed up for the CNC programming.

Originally posted by sy.gunson
Ultimately insurance companies will decide the survival of RR trent engines

I'll not even dignify that with a reply.

Forget the RR engines just replace them all with some GE90 115B's www.le-webmag.com...

VH-OQA update:

Hi guys thought I would post an update on the current state of OQA and what is to be done with her. I had a meeting with the head of QF A-380 maintenance ops last Friday. Whilst waiting for the meeting I was talking with one of the other managers there and he showed me a piece of the lower wing skin removed from the aircraft that was penetrated by a liberated turbine blade. The skin plank section would be around .500" thick and it looked like it had been given the proverbial hot knife through butter treatment. Most impressive. If I think to I might take a pic and post it up.

The conclusion is that the aircraft is repairable and $4.5M has been set aside to devise a repair scheme for it, although at this stage how the repair will be effected is still undecided. The total cost of getting it back in the air is put at around $30M+ and the aircraft is not expected to be back in service until October or November of this year almost 12 months after the accident.

In terms of the accident itself, apparently the only thing keeping the engine together and on the wing was the shaft. If that had failed it's likely the whole engine would have disintegrated and fallen off the pylon. As the manager told me the only thing standing between this incident and the Concorde tragedy was sheer luck, it could so easily have ended in a huge fireball. There are still some very puzzling failures that occurred that Airbus has so far not been able to get to the bottom of particularly in regards to one of the main electrical busses failing when it shouldn't have and various other systems dropping out. Personally I am still curious as to why so much of the hydraulic system didn't do "as advertised" with complete failure of one system when it should still have been pressurized off the reciprocal engine and hydraulic fuses doing there job to isolate the damaged areas. I will be going back over to the A-380 operation shortly on a permanent basis so I will attempt to get to the bottom of all this and will keep you posted on anything I see or hear.

LEE.

Manufacturing giant Rolls-Royce has said the mid-air failure of one of its Trent 900 engines on a Qantas superjumbo had led to costs of £56m. The explosion in the engine forced an emergency landing of the A380 in November last year. The one-off cost contributed to annual pre-tax profits dropping 76% to £702m in 2010 from £2.96bn.

BBC


Seems to have put a dent in their profit margins in the short term at least? Wonder if this will lead to more airlines switching to a different engine in the future though?

Originally posted by thebozeian
VH-OQA update:
The skin plank section would be around .500" thick and it looked like it had been given the proverbial hot knife through butter treatment. Most impressive. If I think to I might take a pic and post it up.

I'd love to see that picture if you get a chance to post it!

... will keep you posted on anything I see or hear.

Thanks for the update Lee, I find it fascinating!

I look forward to the next update.

Originally posted by solidshot
Seems to have put a dent in their profit margins in the short term at least? Wonder if this will lead to more airlines switching to a different engine in the future though?

I don't know but Rolls Royce stock is up almost to where it was back before the accident so investors must think the overall impact on the business of any lost jet engine sales will be minimal. In fact the stock is up about 30% from a year ago.

Regarding Qantas profits, if I were Qantas I'd be going after Rolls for reimbursement of all related expenses. Their only hit should be some lost ticket sales if anyone is afraid to fly them, but I'm not afraid, I still think they are one of the safest airlines.

It seems that Quantas and Singapore Airlines have found cracks within the wing structures?

BBC


So are they actually strong enough to cope with continuous take offs and landings with a vehicle of the size and weight?

reply to post by solidshot

It doesn't sound to me like the size and weight is a factor. The source you linked to doesn't say much, but this one has more information:

www.smh.com.au...

Airbus had ruled out as a cause of the cracks flight loads, fatigue or the large size of the aircraft.

They claim the problem is linked to the 7449 material used, rather than the size:

Airbus's head of engineering, Charles Champion, told Fairfax Media that its analysis had determined that the tiny cracks posed no threat to the safety of the aircraft.

"The aircraft is absolutely safe because there are so many ways for the loads to travel within the structure of the wing," he said.

"As it really is not a safety issue, we will inspect them over time ... within the next four years – some of them before."

The inspection of the wing ribs will take place when each aircraft is due for heavy maintenance.

The aircraft manufacturer has traced the problem to an aluminium material used in the wing ribs – called 7449 – which tends to be more sensitive to the way the parts are assembled on the wing.

They will inspect for the cracks every 4 years.

However, why did Qantas defer its future orders?

Qantas has a further 11 superjumbos in its fleet which fly long-haul international routes to London and Los Angeles. It will take delivery of a further two A380s next year but has deferred orders for a further six superjumbos by up to six years.

They didn't say what caused the order deferral.

Qantas announced a deferment of deliveries from both Boeing and Airbus before this incident happened and said it was due to the economic conditions.

www.flightglobal.com...

reply to post by solidshot


I do recall some discussion here at ats about the A380 wing during its development phase

A380 fails key structural test
www.abovetopsecret.com...

reply to post by FredT

So they measured a safety margin of 47% instead of the desired 50%? I would still fly it, even 45% is pretty good.

But that's a totally different issue than this latest wing cracking, which sounds like the "skin" might peel off rather than the wing breaking.

reply to post by FredT


Those were the days!! Awesome, er, discussions we had in those days. I miss it

reply to post by waynos


LOL yeah its an all star list of the aviation forum. It was alot of fun, politics + nationalism + industrial concerns always made for an interesting discussion. I miss it too........ sometimes

Well I suppose I should throw my two cents worth in here and update you all.

The rib feet cracks were discovered on VH-OQA (Nancy-Bird Walton) during repair work in SIN. They were noticed during survey work in preparation to remove a section of the lower wing plank inboard of the #2 Engine. My immediate boss has spent nearly half of the last 6-9 months up there co-ordinating the repair work on the hangar floor, so I have had a unique view of what is happening. If i can get hold of the pics I will try to upload a few as some of them are amazing. Whole unique tooling has been manufactured just for this job and as my boss said "this is a less than once in a career opportunity to see something like this". A section of the lower wing plank nearly 20ft long and probably 7-8ft wide has been cut out precisely and was then sent on a custom jig to Germany. There it was used as a template to construct a new lower plank section which is a flush repair. On top of the wing a section probably about 1/4 the size has been fitted but it will not be a flush repair as I believe it will have a doubler placed over the top to aid the structure. The spar which had a hole punched through it by a section of the turbine disk, fortunately was punctured between two manufacturing join sections. This was unbuttoned and a new section placed in while the lower skin was off. This meant the entire wing structure had to be kept perfectly aligned by a veritable forest of jacks! There was also a slice through the wing to body lower butt strap which had the damaged section cut out and a new one flush fitted, once the airframe sealant is put in and its painted you apparently wont know the difference There will be a few internal doublers in the tanks and a pair of telltale straps on the lower wing skin repair but that is about it. A few other minor punctures on the fuselage will also be flush repaired but from a distance I doubt they will be visible. As well, obviously all the severed looms and harnesses, fuel gallery piping and droop nose drives that were damaged have been replaced. All up Airbus is saying there will only be a 240 kg weight penalty which is pretty damn good. At this stage the RTS has slipped from Feb to March, but even that could shift as they have started powering up systems that were shutdown badly over 15 months ago. Until all the electrons start whizzing around we just dont know what else was fried or has corrupted software. Even though many boxes were pulled and tested and wires buzzed out, until it is all put back as a system you just cant be sure.

Now as for the rib foot issue, I dont think it is really a problem, all aircraft develop cracking and sometimes it is due to the material chosen as AB has claimed. Hell, does anyone remember how Boeing 747 Section 41 modifications came about? That was due to the forward fuselage frames cracking and splitting because of the unique "figure eight" double lobe cross section. The frames were manufactured out of a 75 series alloy and pressure cycles caused them to fail. I know guys who did some and they said the first one was found because of banging and clicking sounds heard in the nose and cockpit area during flight, some of the cracks were multiple feet long! In the end they virtually rebuilt the noses with new frames and skin sections and just changed the alloy used. What concerns me is that Airbus only found this due to an unusual circumstance and doesn't seem all that keen to check the rest of the fleet until a C check is performed and it seems not just any C check but only after 4 years which implies that it will be a C2. Claiming that it isn't a problem and wont have a structural implication is a little simplistic given that those loads have to go somewhere else, and it's those "somewhere else's" that concern me. All airliners develop unexpected cracks early in their career, it's a fact of life. But often they appear in places that were not thought likely. So my concern is that "we don't know what we don't know" but have been given a heads up and are not checking quicker.

Ah yes the good old days of debate on ATS, where have all those great contributers gone, Willard856, Zaphod58, intelgurl, Westpoint23, Canada, Darkpr0, Daedelus3, and of course who could forget the legendary and irrepressible Kurt Plummer, better known here as CH1466? Ah yes the good old days....

Twenty Airbus A380s will have to undergo checks for cracks in their wings, the safety regulator has said. The European Aviation Safety Agency (EASA) said the planes, a third of the current fleet, would undergo a "visual inspection" for cracks. A few planes, which have carried out more than 1,800 flights, will need inspections within four days, it said.

BBC

Seems a few more cases of cracking have been found, and checks have been ordered?