Qantas keeps A380s grounded over engine 'anomalies' | Hacker News Reader

Qantas keeps A380s grounded over engine 'anomalies'

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17 pointsgeorgecmu14 comments

Are engines for quad-engine planes designed and maintained as rigorously as engines designed for twin-engine planes? (I know there is ETOPS that dictates maintenance standards for twin-engine planes, but I am asking about the design process rather than day to day operation.)

Or is this just a bug to work out with a new aircraft and engine design? Or is it just random chance?

(Also, it's odd to blame Rolls-Royce for the failures, when the engines are both owned and maintained by Qantas in Singapore.)

>(Also, it's odd to blame Rolls-Royce for the failures, when the engines are both owned and maintained by Qantas in Singapore.)

I'd say it's much more likely that there's some bug in the A380 RR engine than Qantas doing a maintenance job crappy enough to cause a 2 year old engine suffer such a catastrophic failure. You should be able to do the shoddiest maintenance job in the world and not have an engine fail in a way that causes the wing to be pierced.

and not have an engine fail in a way that causes the wing to be pierced

I think this is the bit that is more worrisome than any possible maintenance issues. Jet engines have lots of turbine blades spinning at hellacious rpms. The one catastrophic failure that modern engines are supposed to be designed to prevent is having the blades leave the cowling; this is the sort of failure mode that can result in the failure of a single engine taking an entire plane down (c.f. UAL 232). This is not supposed to happen on modern engines. Ever

I don't think the larger fan blades did leave the cowling. Based on the couple images I saw of the failed engines (e.g. [0]), the smaller, hotter blades farther aft [1] were the ones that punctured the cowling. These have less protection because the wing protects the passengers from flying debris whereas the compression and intake fans stick out far enough to require separate cowling for passenger protection.

[0] http://www.newstalkzb.co.nz/img_up/QantasEngine250.jpg

[1] http://en.wikipedia.org/wiki/File:Jet_engine.svg

Indeed. I remember seeing pictures of engine testing for the 777 where they explosively detonated a turbine blade to test that no pieces would leave the cowling. Engines are literally designed to explode but keep all the pieces inside.

With engines this young, you would have to look at design factors to at least check there is no problem. That's why Qantas has grounded the fleet. Remember, Qantas is the oldest airline to have never suffered a fatality. It's part of their brand equity, and I don't think they want to change that anytime soon.

... have never suffered a fatality since becoming a jet airline. It had quite a few fatalities during the pre-jet era. [1]

One Qantas flight was even shot down by the Japanese in 1942!

(Apologies for the pedantry)

[1] http://en.wikipedia.org/wiki/List_of_Qantas_fatal_accidents

According to Qantas CEO Alan Joyce the engines are not maintained by Qantas.

"This is an engine issue and the engines have been maintained by Rolls-Royce since they were installed on the aircraft..."[1]

[1] http://www.adelaidenow.com.au/plane-reportedly-qantas-sheds-...

Rolls-Royce has also recommended "basic precautionary checks" be carried out on all Trent 900 engines (i.e. the model that failed)[2]

[2] http://www.abc.net.au/news/stories/2010/11/05/3057785.htm

Interestingly, Trent 895 engines were the cause of the only 777 hull-loss incident.

I'm making a mental note to only fly on planes with GE engines from now on :)

The blame there seems to be more that the Trent 895's fuel-oil heat exchangers (FOHE) were presented with too much ice than that the design of the engine was at fault: http://en.wikipedia.org/wiki/British_Airways_Flight_38#Final...

"3) The FOHE, although compliant with the applicable certification requirements, was shown to be susceptible to restriction when presented with soft ice in a high concentration, with a fuel temperature that is below -10°C and a fuel flow above flight idle.

4) Certification requirements, with which the aircraft and engine fuel systems had to comply, did not take account of this phenomenon as the risk was unrecognised at that time."

According to Qantas CEO Alan Joyce the engines are not maintained

Well, yeah, that's why they blew up!

Indeed, but this is the way it is now. Halliburton fails to do their job right in the Gulf of Mexico, blame the Brits. Quantas fails to maintain its engines, blame the Brits. I don't really care when it's just Hollywood, but Obama brought it into the real world.

In this case, the Germans. The engines were maintained by Rolls-Royce Deutschland.

It almost doesn't matter - BP in the US is a separate operating division too.

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