Discussion:
Airbus A380 engines
(too old to reply)
JF Mezei
2010-11-08 07:11:07 UTC
Permalink
Qantas has just announced that an inspection of their 6 A380s (24
engines) has revealed 3 engines on 3 aircraft with oil leaks in the
turbine section.


If this had been a design problem, shouldn't Singapore Airlines (the
oldest operator of the 380 with Rolls Royce engines) have had that
problem first ?

If Singapore has not had the problem, wouldn't this point to maintenance
practices for Qantas ?


Also, is the failed engine considered an uncontained failure, or did
containment work with the debris being pushed towards the back of engine
instead of radially propelled ?

There is a picture of some bent metal on the top surface of the wing.
Does this mean that some engine part pierced through the wing ? If so,
wouldn't that have caused significant risk of catastrophic failure (aka:
fuel in tank catching fire) ?
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Miles Bader
2010-11-08 07:29:11 UTC
Permalink
Post by JF Mezei
There is a picture of some bent metal on the top surface of the wing.
Does this mean that some engine part pierced through the wing ?
Yes; there's also a matching hole on the _bottom_ of the wing...

(Every place I've seen seems to be calling it an uncontained failure at
this point)

-Miles
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Roland Perry
2010-11-08 08:36:52 UTC
Permalink
Post by JF Mezei
If Singapore has not had the problem, wouldn't this point to maintenance
practices for Qantas ?
aiui these engines are in effect leased from Rolls Royce, to include
lifetime maintenance. So all engines, irrespective of carrier, should be
in the same maintenance regime.
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A Guy Called Tyketto
2010-11-08 09:02:51 UTC
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Post by JF Mezei
Qantas has just announced that an inspection of their 6 A380s (24
engines) has revealed 3 engines on 3 aircraft with oil leaks in the
turbine section.
If this had been a design problem, shouldn't Singapore Airlines (the
oldest operator of the 380 with Rolls Royce engines) have had that
problem first ?
It was. there was an AD posted back in early-mid August about
the Trent 900s that should have been adhered to. This should have
affected all A380s except those flown by UAE and AFR, who are using the
GE/PW engines.

http://www.channel4.com/media/c4-news/pdf/EASA_AD_2010-0008R1_1.pdf

Pretty condemning stuff.
Post by JF Mezei
If Singapore has not had the problem, wouldn't this point to maintenance
practices for Qantas ?
Depending. The issue may have existed all along, and hadn't
cropped up for anyone. However, with the AD having been posted,
everyone should have been aware of this. In SIA's case, as well as
everyone else affected (DLH), it's come down to really good luck. This
could have happened to either of them at any time.
Post by JF Mezei
Also, is the failed engine considered an uncontained failure, or did
containment work with the debris being pushed towards the back of engine
instead of radially propelled ?
This is a UEF. Uncontained Engine Failure. None of the damage
of the engine was contained in the engine, nor the cowling. Just by
where the parts of the engine fell says enough in itself (the UEF
happened in Singapore; parts landed in Indonesia). The Age put out a
very nice PDF of the engine, as well as the pieces that were recovered.
Note the statement about how much heat was generated, relative to the
colour of the nacelle and the rest of the fuselage:

http://images.theage.com.au/file/2010/11/04/2026935/0511qantas.pdf
Post by JF Mezei
There is a picture of some bent metal on the top surface of the wing.
Does this mean that some engine part pierced through the wing ? If so,
fuel in tank catching fire) ?
Not completely through the wing, per se. From some of the pics
I've seen, it looks like it caused part of the metal on the slats to
bend, but definitely not where fuel would have caught fire. They got
the engine shut down in enough time, which was good, and none of the
lines were severed. Either way, the UEF could have caused catastrophic
failure, but with the way the metal on the slats looks, there would
have been more of an issue with landing than fire. Even with as much
fuel as they dumped, they wouldn't have been in a clean configuration
to land the plane and get her stopped.

Interesting side note is that the B744 they sent to ferry the
stranded passengers also had a UEF at WSSS 2 days later; Another
Rolls-Royce engine (RB211). That one did have a number of ADs out on it
over the past couple of years.

BL.
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Roland Perry
2010-11-08 11:56:31 UTC
Permalink
Just by where the parts of the engine fell says enough in itself (the
UEF happened in Singapore; parts landed in Indonesia).
The island of Batam (Indonesia) where the parts landed is only five
miles from the end of the runway (the same as the distance from EWR to
Manhatten). The plane was climbing over the island when the accident
happened. http://goo.gl/maps/vsP1
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Robert Neville
2010-11-08 14:16:47 UTC
Permalink
Post by A Guy Called Tyketto
Interesting side note is that the B744 they sent to ferry the
stranded passengers also had a UEF at WSSS 2 days later; Another
Rolls-Royce engine (RB211). That one did have a number of ADs out on it
over the past couple of years.
And even more interesting was that the pilot of the A380 was a passenger on the
B744!
JF Mezei
2010-11-08 16:44:17 UTC
Permalink
Based on the AD posted by a guy called Tyketto, it would seem a case of
premature wear. Is this a fair assesment ?

If this is found to be a systematic issue, how can this be dealt with ?

Or would they just reduce the number of hours/cycles before each
inspection ?

Will airlines have to cannabalise a 380 to get "good" engines to replace
engines on other aircraft that begun to show signs of wear on those
shaft splines ?


If the shaft and/or the strutures that hold the shaft are faulty, is
this something that can be replaced ? Or is the engine basically a
write-off and Rolls will scavenge components from it to build a totally
new one ?


In the case of the Sioux City UA232, what happened to DC10 engines
afterwards ? Were they all Xrayed up the wazoo to confirm that this was
a one-off manufacturing defect ? During that time, did DC10s continue
to fly ?


Considering that Qantas says it has found traces of oil on 3 engines,
wouldn't this point to a systematic problem as opposed to a one off ?

Qantas might have been quilty of not inspecting the engine to detect the
flaw prior to the accident, but such flaw shouldn't have happened to
begin with.

Any prognosis on how this will turn out ?


What sort of lead time is needed for Rolls to produce engines to replace
failing ones ? I know that for landing gears, some of the parts take
months of milling to get just right. Is that the same case for engines ?
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Roland Perry
2010-11-08 19:13:08 UTC
Permalink
Post by JF Mezei
Qantas might have been quilty of not inspecting the engine to detect the
flaw prior to the accident
Isn't the servicing done by Rolls Royce?
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matt weber
2010-11-09 00:51:58 UTC
Permalink
On Mon, 08 Nov 2010 11:44:17 -0500, JF Mezei
Post by JF Mezei
Based on the AD posted by a guy called Tyketto, it would seem a case of
premature wear. Is this a fair assesment ?
If this is found to be a systematic issue, how can this be dealt with ?
Or would they just reduce the number of hours/cycles before each
inspection ?
Will airlines have to cannabalise a 380 to get "good" engines to replace
engines on other aircraft that begun to show signs of wear on those
shaft splines ?
If the shaft and/or the strutures that hold the shaft are faulty, is
this something that can be replaced ? Or is the engine basically a
write-off and Rolls will scavenge components from it to build a totally
new one ?
In the case of the Sioux City UA232, what happened to DC10 engines
afterwards ? Were they all Xrayed up the wazoo to confirm that this was
a one-off manufacturing defect ? During that time, did DC10s continue
to fly ?
The problem with UA232 was two fold. Manufacturing should have caught
the defect, and maintenance should have spotted the defect. Dye from
two dye inspections was found on the disk, so the defect was
apparently visible on at least two engine overhauls before the disk
finally failed. Nobody noticed it. As I recall the NTSB report was
quite critical of both GE and UA for not spotting the problem.

The flaw that caused the failure was about the size of a grain of
sand.
Post by JF Mezei
Considering that Qantas says it has found traces of oil on 3 engines,
wouldn't this point to a systematic problem as opposed to a one off ?
This may in fact be covered by an Airworthiness Directive issued last
summer. At this point I believe 6 engines have been removed from
service, 3 at QF, and both LH and SQ have pulled engines that failed
inspection.
Post by JF Mezei
Qantas might have been quilty of not inspecting the engine to detect the
flaw prior to the accident, but such flaw shouldn't have happened to
begin with.
Any prognosis on how this will turn out ?
You can expect another Airworthiness directive, and at this time,
there is no clearing action on the outstanding AD, so at some point RR
is going to have to re-design something...
Post by JF Mezei
What sort of lead time is needed for Rolls to produce engines to replace
failing ones ? I know that for landing gears, some of the parts take
months of milling to get just right. Is that the same case for engines ?
Most buyers buy spare parts along with aircraft. However I believe
that QF bought a maintenance package for the A380's, so the problem
belongs to someone else, who presumably has spares. I don't know if
that is Airbus or RR however...
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John Levine
2010-11-09 05:13:02 UTC
Permalink
Post by JF Mezei
If this had been a design problem, shouldn't Singapore Airlines (the
oldest operator of the 380 with Rolls Royce engines) have had that
problem first ?
Reuters says that Qantas operates their engines at higher thrust than
other airlines. They also fly longer routes so the plane is heavier
at takeoff.

http://www.reuters.com/article/idUSTRE6A62P420101109

R's,
John
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A Guy Called Tyketto
2010-11-10 09:59:55 UTC
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Post by John Levine
Post by JF Mezei
If this had been a design problem, shouldn't Singapore Airlines (the
oldest operator of the 380 with Rolls Royce engines) have had that
problem first ?
Reuters says that Qantas operates their engines at higher thrust than
other airlines. They also fly longer routes so the plane is heavier
at takeoff.
http://www.reuters.com/article/idUSTRE6A62P420101109
R's,
John
And this just in. SIA has now grounded all of their A380s to
replace their engines.

http://tinyurl.com/248d882

Depending on how long this 'replacement' takes, I'd guess some
of their (both QFA and SIA) will be pulling out some of their
mothballed B744s from Mohave or Victorville to prevent any interruption
in service.

BL.
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Roland Perry
2010-11-10 11:13:59 UTC
Permalink
Post by A Guy Called Tyketto
And this just in. SIA has now grounded all of their A380s to
replace their engines.
http://tinyurl.com/248d882
"One aircraft in Melbourne, one in Sydney and another in London have
been forbidden to fly until the engines are replaced."

And yet the video clip says they are flying them to Singapore to change
engines!

With an implication that it's one engine per plane which needs replacing
(they should be able to fly safely on three, especially when empty).

Maybe they have enough spare engines in Singapore already?
Post by A Guy Called Tyketto
Depending on how long this 'replacement' takes, I'd guess some
of their (both QFA and SIA) will be pulling out some of their
mothballed B744s from Mohave or Victorville to prevent any interruption
in service.
How long, approximately, would it take to return such an aircraft to
service?
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JF Mezei
2010-11-10 18:03:24 UTC
Permalink
Post by A Guy Called Tyketto
And this just in. SIA has now grounded all of their A380s to
replace their engines.
http://tinyurl.com/248d882
The text of the article now states that they grounded only 3 aircraft.
So it isn't as fatalistic as grounding the whole fleet.

But suddently grounding 3 aircraft does presuppose than oil leaks had
been identified and considered acceptable, but now, they decided it was
no longer acceptable so they ground those 3 aircraft that had previously
been identified as having leaks.

I find it intesting that Singapore, which got such a head start
operating 380s, would only now experience such events, at same time as
Qantas, which has a younger fleet.

What would be needed now is for the airline to publish the number of
hours of operation for their failed engines (as well as build date), so
we could compare the Singapore to Qantas engines.

If the oldest Singapore engines are fine, and only younger ones are
experiencing this wear, then a bad batch at Rolls could be suspected.
(or perhaps a change in manufacturing method when Rolls moved into a
higher production rate etc).


Question: Can an engine be totally disassembled and any/every part
replaced, or are there parts which are permanently attached to each
other and cannot be replaced without replacing a huge chunk ?

For instance, can the shafts be replaced ? Or would such a replacement
require the replacement of the shaft and all turbines attached to the
shaft ?

Are turbine blades removable ?






Bad news for Rolls: a 787 equipped with Rolls engines had to make an
emergency landing in Texas due to smoke in cabin. ( this is probably
absolutelty not related to the engines since the 787 doesn't use bleed
air for cabin air, but it still bad image for Rolls).


Would be interesting to listen in to a conference call between the CEOs
of Qantas, Singapore and possibly Lufthansa. If Rolls doesn't have
enough spare engines, this is going to be a game of musical chairs with
Singapore and Qantas fighting to get the spare engines.


Speculation: once they've decided this is caused by premature wear, they
will re-instate the fleet, but with more frequent inspections until
Rolls can fix the problem.
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A Guy Called Tyketto
2010-11-11 08:33:30 UTC
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Post by JF Mezei
The text of the article now states that they grounded only 3 aircraft.
So it isn't as fatalistic as grounding the whole fleet.
But suddently grounding 3 aircraft does presuppose than oil leaks had
been identified and considered acceptable, but now, they decided it was
no longer acceptable so they ground those 3 aircraft that had previously
been identified as having leaks.
I find it intesting that Singapore, which got such a head start
operating 380s, would only now experience such events, at same time as
Qantas, which has a younger fleet.
What would be needed now is for the airline to publish the number of
hours of operation for their failed engines (as well as build date), so
we could compare the Singapore to Qantas engines.
If the oldest Singapore engines are fine, and only younger ones are
experiencing this wear, then a bad batch at Rolls could be suspected.
(or perhaps a change in manufacturing method when Rolls moved into a
higher production rate etc).
Question: Can an engine be totally disassembled and any/every part
replaced, or are there parts which are permanently attached to each
other and cannot be replaced without replacing a huge chunk ?
For instance, can the shafts be replaced ? Or would such a replacement
require the replacement of the shaft and all turbines attached to the
shaft ?
Are turbine blades removable ?
They more than likely are. Given the fact that now QFA, SIA,
and DLH are now changing some of their Trent 900s.. Then again, now,
another AD has been issued for the Trent 900:

http://tinyurl.com/2w5u55u

The Trent's flight cycles just got shorter.
Post by JF Mezei
Bad news for Rolls: a 787 equipped with Rolls engines had to make an
emergency landing in Texas due to smoke in cabin. ( this is probably
absolutelty not related to the engines since the 787 doesn't use bleed
air for cabin air, but it still bad image for Rolls).
Worse. Boeing has now grounded all B787s because of this. They
lost (but didn't lose) their PFD, and suffered internal and structural
damage. The aircraft in question was here a few months ago at MHR doing
some tests before flying down to NYL. It departed from there for this
particular test. This might not be Trent 1000 related, but seeing that
they pretty much blew one up on demonstration, this doesn't bode well
for RR as well.
Post by JF Mezei
Would be interesting to listen in to a conference call between the CEOs
of Qantas, Singapore and possibly Lufthansa. If Rolls doesn't have
enough spare engines, this is going to be a game of musical chairs with
Singapore and Qantas fighting to get the spare engines.
Riddle me this: How much time would it take, let alone any
structural changes to the fuselage would be needed, should SIA, DLH, or
QFA decide to pull off the Trent 900s for the GE/PW engine? Could they
purchase the engines separate, and have them installed?

BL.
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JF Mezei
2010-11-17 15:58:49 UTC
Permalink
There are now articles such as:
http://www.heraldsun.com.au/news/rolls-royce-engines-were-modified-well-before-qantas-mid-air-scare/story-e6frf7jo-1225952824220

which quotes John leahy as confirming that the problem has been fixed in
later engines. So this would seem to limit bad engines to those
manufacturerd between certain dates.

Airbus is having to return some engines to Rolls so they can be sent to
Lufthansa/Singapore/Qantas to replace faulty ones. (Which will give
Airbus a good excuse to not be able to deliver the 20 A380s it had
promised to deliver in 2010).

The good news is that if the problem has already been identified and
fixed, it means that production can continue normally as soon as Rolls
catches up on engine production after exchanging existing bad engines at
LH/SG/QF.

But this does pose some questions:

Are engine containment tests sufficient ? The Trent 900 clearly passed
certification tests. Yet in this incident, there was uncontained damage.

Are containment tests limited to the fan blades, or are there also tests
/requirement for containment of the engine core ?


What I don't understand here is why an oil fire would cause an engine to
disintagrate. Considering the engine core is designed to widthstand high
pressure and temperatures, why would an oil fire cause so much damage ?

Or is this a case of the burned oil resulting in much higher friction in
that spline, which caused wear on teh spline which caused the axle to
gain forward/backward movement, resulting in some blades moving back and
hitting the casing ?

Another article I read simply mentioned that a disk just cracks and few
away due to oil fire.
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