

Pre-flight cracks in 787 engine  - kghose
http://www.ntsb.gov/news/2012/120927.html

======
eduardordm
I experienced such failure on a plane I was flying (CFM56). I don't remember
what the exact problem was, but it had something to do with a batch of
materials they used in the construction of some blades. A whole lot had to be
replaced. It was my 138th hour flying as capt.

This is a new engine, without figuring what causes those fractures, NTBS
should ground them. I bet they already know what it is.

My father (37 year of flying) always tell me stories where engines in the
industry had vibration resonance problems that caused fractures in the whole
airplane those engines never ended up flying.

------
andrewcooke
more info - [http://www.flightglobal.com/news/articles/ntsb-urges-
groundi...](http://www.flightglobal.com/news/articles/ntsb-urges-grounding-
for-certain-genx-powered-787-and-747-8s-376525/)

(this is serious because - as far as i can tell - this engine has a 330 minute
ETOPS rating <http://www.geaviation.com/press/genx/genx_20120308.html>
<http://en.wikipedia.org/wiki/ETOPS> which means that a twin engine plane
(like the dreamliner) can fly 5.5 hours (the number in the report above) from
"safety" (eg over the atlantic), so if one engine fails the other must
continue working for that time. if the problem is common then that is _not_ so
reasonable an assumption...)

(not all dreamliners are affected; rolls royce also provide engines)

~~~
marklabedz
A little more info on ETOPS and the challenges created by multiple similar
failures within a small population...

There are two parts to ETOPS (tongue in cheek "Engines Turn or Or People
Swim")..The first is the certification to design standards, including flight
testing. The second, and perhaps more crucial element, is the
operations/procedures certifications. In the first stage, the entire system
(engines, airframe, fuel system and everything else) is evaluated as a
comprehensive whole. Essentially, you're looking to eliminate single points of
failure.

The second part is arguably more important as it deals with the statistical
failure rates. The assumption is that a modern jet (turbofan) engine is highly
reliable. As the basis of such procedures, multiple, similar failures are
worrisome. An airline must have approved ETOPS operations to fly routes
requiring ETOPS (a certified airplane is necessary but not sufficient). Common
operational procedures include not replacing both engines at the same time,
servicing similar fuel system components together, etc. Basically, avoid the
possibility of introducing a single point of failure into otherwise redundant
systems.

~~~
cstross
Single points of failure can emerge but hopefully they're rare. The classic
case is something like British Airways Flight 38 at Heathrow in 2008:

<http://en.wikipedia.org/wiki/British_Airways_Flight_38>

(By sheer good luck and good piloting skills the crew were able to make it
over the runway threshold after both engines lost power during final approach:
injuries and a hull loss, but no deaths. Problem was a design flaw in the fuel
oil heat exchangers, only triggered by unusual meteorological conditions on a
long flight. Both engines had the same design issue and were drinking the same
fuel ...)

~~~
rogerbinns
And if it had been a 4 engine plane the same issue would have been present (or
even a 24 engine plane).

Sadly I can't find the article any more but did read one about how each new
generation of commercial aircraft is increasingly aerodynamically efficient.
The side effect of that is how much further they can glide from the same
starting point (less drag). Its hard to find numbers that aren't speculation
but it seems like 1980s era designs (eg 767) are around 15:1 and current
generation are around 20:1.

Wikipedia even has a page about flights that required gliding:
[http://en.wikipedia.org/wiki/List_of_airline_flights_that_re...](http://en.wikipedia.org/wiki/List_of_airline_flights_that_required_gliding)

------
sbierwagen
As every Boeing employee reliably complains, every time a story like this
comes out, Boeing doesn't make the engines. They're GE engines. It's a GE
problem. They're just mounted to a Boeing plane.

When Bridgestone makes bad tires that fall apart while driving, the headlines
are not "tires on Ford car explode, kill family", it's "Bridgestone tires
burst into flame, kill busload of orphans".

And, as andrewcooke points out, not every 787 flies with GE engines, since
Rolls Royce is also a vendor.

~~~
bobbles
If those bridgestone tyres happened to be the ones that came WITH the car as
you purchased it, there would likely be strong backlash against Ford.

~~~
gvb
They did.
[http://en.wikipedia.org/wiki/Firestone_and_Ford_tire_controv...](http://en.wikipedia.org/wiki/Firestone_and_Ford_tire_controversy)

------
alphasierra
For those of you not following these events closely: the 747-8 and the 787
(both new) both utilize a very similar engine from GE (the GEnx).

The GEnx 1B (787) failed in July this year and kicked off an investigation
that is trying to determine if there is an engineering or manufacturing
problem in the parts that connect two shaft pieces together to form the main
shaft in the engine.

The GEnx 2B (747-8) failed in early September this year and the initial
investigation is not complete.

This memo confirms that the 747-8 and the 787 failures are _NOT_ related.

That being said, the NTSB wants to pull the ETOPS certificate from the -1B
engines which would effectively ground the majority of the 787 fleet (the 787
is optimized for long flights which would be majority over water/out of
gliding range and the GEnx has the widest install base on the 787).

The FAA has indicated that they will take a watching brief for the time being.

------
omegant
That's a big failure for engines that have been ground tested only. I can't
understand how they didn't check (I mean fresh engines just off reasembly line
for inspection) them before. This is more or less normal with new models but
maybe not this way.

------
photorized
What's unsettling is that the failure is in the inherently reliable component
(shaft).

------
lmg643
another reason not to fly on the 787 until it's been in use for several
years...

~~~
marklabedz
Its not just the 787 that uses these engines.

EDIT: ...and not all 787s use these engines.

------
jjm
Sounds kind of crazy to not test engines under real world conditions. What I
mean is not be able to test it under conditions found during actual work
(found in the air) prior to release.

