@paperhanger
i'm quite sure the section rotates. anyway what do you suppose you would attach with that many bolts except the fan?

Why not record the cockpit sound for many more hours on a conventional recorder able to record hours of conversation (possibly video also) a robust HD might survive a crash but such a device might be useful for investigating incidents such as this where the plane lands

The CVR recording times compared to changing technology have been a joke for years. However, they are finally changing and 20 hour CVRs will become norm on new aircraft... but not until after 2020 (ish).

The length of time recorded on a CVR has less to do with technology than privacy.
Didn't the pilot unions insist on 30 minutes?

For US-registered aircraft, 14 CFR 121.359 has required 2-hour recording since 2012. Most Airbus (certainly A380) also have 2-hour recorders. QF32 had a 2-hour recorder but the recording of the actual incident was still overwritten because it took so long to suppress engine #1.

It's easy to say "look at my new toy MP3 recorder that can record 10 years of audio". Your MP3 recorder isn't required to be certified under stringent regulations (which are there for a purpose) including being able to survive crash, fire, submersion at high pressure, etc., and emerge with readable memory. What's more, MP3 is very compressed; I don't know, but I expect CVR recordings aren't compressed because compression could fail and make the recording unreadable. Uncompressed audio needs a lot more memory.

Having said that, the blame culture in many airlines, even among pilots, creates pressure to limit recording time and make recordings erasable. Even here on what's supposed to be a professional pilots' forum, the lynch mob was out for those CA pilots after their famous go-around at SFO almost before their engines had stopped. Fix that blame culture and you go a long way to making long-period CVRs acceptable.

I'm guessing the point some are making is that for incidents such as the AF dversion we are on about here there's no need for a robust system...then again it would still have to interface with the aircraft's audio system so there would be certification issues.

However fundamentaly we increasingly live in a society where many seem to think the number one priority in any situation is to have a recording, or access of a recording, of an event. I assume the idea is this can then be used for a variety of purposes ( monetary, regulatory, increasing hits on social media outlets). Frankly I'm not keen on moving much beyond where we are now.......guarantee privacy, fix the blame culture, then it will be easier to make long period DVRs acceptable.

trying to attach another diagram of the front of this engine

History tells us different....

https://en.wikipedia.org/wiki/Contin...ss_Flight_2574

thank you for that wow :)

so the central bit of ripped metal is indeed all that is holding the fan AND the low pressure compressor stages.
didn't expect that.

Pax2908's drawing shows exactly what was argued earlier. The LP compressor hub flange is fixed to the rear of the fan disc and is in fact only supported by the fan disc. When the fan separates from its shaft one would expect the LP compressor hub (together with its 5 stages of compressor blades) to be thorn out of the engine but instead the compressor hub mounting flange separated quite nicely, despite the many fastening bolts.

True and even with engines mistakes have been made. But engines are very critical parts so no margin for such errors, very strict procedures and inspections. Also there's a lot of electronics monitoring the performance of the engine, I would think that "half of the bolts missing" would cause a lot of vibrations and make all the alarms go of when they do a test run of the engine. But indeed never say never...

Fasteners gone from the LPC inner support structure/rings also.

Failure was not likely caused by a few unnoticed missing fasteners during assembly/inspection.

Photo link:
http://www.pprune.org/attachments/ru...lantic-one.jpg
......

Even aerospace has been know to miss a bolt or two:

https://upload.wikimedia.org/wikiped...7_accident.jpg

More details at:
https://en.wikipedia.org/wiki/NOAA-19

This type of "mishap" is sometimes caused by interrupted or resequenced work.

Sorry, seems my understanding of the diagram was wrong, but if this is where the LPC was attached to the fan I would still hope that they broke off by design.

Depends on your definition of "a lot". An hour of uncompressed CD quality stereo audio is 527 MB. My current iPhone holds 64 GB of storage, that's equivalent 124 hours of uncompressed stereo CD quality audio. The memory requirements are trivial in this day and age. Solid state digital CVRs exist and are certified, all you need to do is stick more memory inside them.

#9 in "your" photo I think one sees clearly two types of holes, there are 24 which seem "empty" (no fasteners there, I suppose these only are there to clear the 24 fasteners that belong only to the fan section, see also the photo showing the engine in the shop with only 6 fan blades on); and then there are 3*24 holes which ~all seem to show an end of the fastener still inside ... so indeed would seem as a clean break (perhaps as per design).

pax2908,

Thanks, see that every 4th hole is used for the fan/LPC attachment most appear darker as if a larger dia.

Main point of photo link was to show what appear to be the missing or sheared fasteners of the inner compressor rings which would have all holes filled when assembled.
......

Big pity, I read earlier, that the forward facing camera doesn't cover the outboard engines. Had it been otherwise, it might have made an eminently watchable engineering training video for decades afterwards!

Earlier in the thread some postulated that the majority of the missing lump would likely have flown off safely forward and down.

I have my doubts that any of it took that route.

Looking at the cleaner breaks at the bottom half of the remains, and the rent upward pylon fixings and the leading edge dents, my guess is that the fan in the fancase let go first at the bottom and folded up and then ripped off top-last over the top of the wing - if you blinked you missed it no doubt!

Now we know why they make you close the cabin shades in cruise. ;)

Well, I am expecting that the fan went whichever way it felt like, and possibly whole. The close fit in the front cowling structure will have seen pretty much instant wrenching of that whole assembly from the main pod when the fan moved laterally enough to chew into it on its way out. :ooh:
Thanks for the diagram pax2908.:ok: