Apollo11
Posts: 24082
Joined: 6/7/2001 From: Zagreb, Croatia Status: offline
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Hi all, quote:
ORIGINAL: Dixie quote:
ORIGINAL: Apollo11 OK - here is the repost (original here http://www.matrixgames.com/forums/tm.asp?m=2563820&mpage=196�): Martin, as our in house (erm... in "THE THREAD" ) aircraft engine expert - what do you think about A380 and Rolls-Royce Trent 900 issues? I understand that both recent events were down to problems somewhere in the oil systems. The Qantas one looks like a failure of a turbine bearing causing it to seize and then spit out a few blades. IIRC the Trent is based on the RB211 but with a few added goodies (extra LP turbine stage for example). It looks like it's either the HP or IP turbine that's given up and broken away and taken a big chunk of translating cowl (part of the thrust reverse system) and cold-stream duct with it. The image shows a nice chunk of the core engine missing just in front of the bulge in the engine fairing. Sitting at home with a nice knowledge or aircaft I can happily say losing one of four engines isn't an issue, but if you're sat on an aeroplane that's just lost an engine it's probably different Have I bored you enough yet? I can get more technical if you want (you really don't btw) quote:
ORIGINAL: Dixie Not designed to as such Offhand I can't remember exactly how the casings are built, but iirc there isn't anything to really stop the turbine blades if the do break loose. There's a casing (like a kevlar net I think) at the front to contain the LP fan blades (because they're bloody huge) in the event they break away. The turbine blades by comparison are a lot smaller. Engines can (and usually do) last for thousands and thousands of hours 'on wing'. I'm sure that my instructor mentioned (in February) that TAP had an engine on one of their aircaft since the 90's. Especially in the civvy world having an engine that broke down on a regular basis would kill a company. Seeing as airlines are based on making money they'd soon stop buying your stuff if it broke down every 1,000 hours or so. On the RB211 the final turbine stage (the largest blades) are about a foot long, the further forward in the engine you go the smaller the blades are. The HP blades are really tiny, again iirc, only a couple of inches. The LP fan blades are about 3' long each and made from a heavy titanium alloy so they're more of a problem if they break free. Usually I only see the LP fan and the LP turbine first hand, everything else I see through a boroscope so it's harder to judge sizes. I've got no reason to think the turbine blades are any bigger on the Airbus. As for the wing, it's an airframe part and is therefore boring to me (even if I am technically qualified for airframe work). But, the wing spars are chunky bits of metal and are set back from the leading edge, the hole just looks bad because it's in the wing. The leading edge would maybe contain hydraulic lines (for the LE slats), engine controls and maybe refuel pipework. I'm not sure on how the AB has it's hyds set up, newer aircraft are generally less reliant on hydraulics than older ones so there might not be anything much leading through the front of the wing. Great stuff - thanks Martin! Please keep it coming (we really love your expertize)!!! The main problem was that the flying parts (when the engine blew off) struck some very sensitive things in A380's win... the control commands for #1 engine were severed (the #2 blew out) and the pilot only controlled the #3 and #4 afterwards... it was much more dicier than it looked like at the first glance (i.e. just loosing one single engine out of 4)... BTW, I was also under impression that fan / blades failures are not such catastrophic events (I don't recall reading about any similar incident in years - perhaps even decade)... I also thought that the engine cover could have prevented flying parts (obviously very wrong)... Thus the Quantas A380 was very very lucky... the parts could have hit passenger cabin or some other system and rendered aircraft unflyable... scary thought... Leo "Apollo11"
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