AF66 CDG-LAX diverts - uncontained engine failure over Atlantic
Stumpy, I been wondering the same thing - was there a fan module change or similar maintenance done recently that wasn't done properly...
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number0009, infieldg & tricityb,
Thanks for the new photos, they help in understanding where the fracture of the shaft occurred. What can cause this, besides a material defect in the shaft, is the bearing starting to fail. The fan loses its center of rotation and begins to chew into the outer casing about the time the shaft fails and what you see in the photos is the end result. This is speculation on my part, but it is a viable scenario of events.
Loose rivets,
The fractured portion of the part you see is a piece the stub (short) fan shaft as it tapers to meet the LPT shaft, not an attachment to the shaft...
Thanks for the new photos, they help in understanding where the fracture of the shaft occurred. What can cause this, besides a material defect in the shaft, is the bearing starting to fail. The fan loses its center of rotation and begins to chew into the outer casing about the time the shaft fails and what you see in the photos is the end result. This is speculation on my part, but it is a viable scenario of events.
Loose rivets,
I can't believe that fractured part is the only attachment to the shaft. Surely there's a supportive ring/hub that's missing that's normally further forward?
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This is the GP7200 bolted ring that attatches fan - hub - IP Drum, where all the fasteners have disappeared.
OPen the below image and you can clearly see the fan hub retention nuts and Allen bolts through to IP Drum.
I would hazard that on AF66 the Allen bolts are still there but I can clearly see several sheared fan hub bolts.
Hydrogen Embrittlement, maybe?
OPen the below image and you can clearly see the fan hub retention nuts and Allen bolts through to IP Drum.
I would hazard that on AF66 the Allen bolts are still there but I can clearly see several sheared fan hub bolts.
Hydrogen Embrittlement, maybe?
Last edited by Stumpy Grinder; 3rd Oct 2017 at 03:46.
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CVR. Is it available?
Thinking of QF32. They could not shut down one engine so the CVR kept running. The CVR of the incident was overwritten because CVR only records 30 minutes.
As I recall, AF66 kept pax on aircraft for quite some time after landing. Does the CVR keep running when only the APU is running? If so, what is the likelihood of the CVR not being of any use to the investigation? i.e. overwritten while on ground.
As I recall, AF66 kept pax on aircraft for quite some time after landing. Does the CVR keep running when only the APU is running? If so, what is the likelihood of the CVR not being of any use to the investigation? i.e. overwritten while on ground.
Considering how much TV a hard drive can hold, nowadays it would be very easy to have forward and rearward looking cameras with hours of storage time.
Two cameras on the tail plane tips looking forward would capture a lot of possible inflight events.
Two cameras on the tail plane tips looking forward would capture a lot of possible inflight events.
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The incident occurred 2 hours before the plane was on the ground; the lead-up to it (a good 20 minutes of shifting headings) could only be on the CVR if it had been turned off in the air. If the crew wanted a potential evacuation procedure to be recorded on the CVR and only turned it off after the plane was confirmed safe, the event itself won't be on it. The FDR is going to be much more useful, I bet.
RE the comments about stopping the CVR in flight ..I don't think an SOP of pulling the CVR recorder in flight is a good thing at all. With the benefit of hindsight doing so might have been in the current AF investigation but what about a hypothetical incident which unlike this one doesn't end well, and unfortunately ends up with a crumpled heap of metal under the approach or off the overrun.
Let's say an engine goes pop as it did in this case, the issue is contained OK initially and a decision is made to pull the CVR.....since the CVR was stopped we now have a well preserved record from the cruise of a thump, somebody calling for a severe damage separation checklist, a bit of T-DODAR....and then nothing....no record of any subsequent analysis done by the crew, any reassessments during the descent, any descent/approach briefing, any conversation/comments made during the approach.
There certainly seems to value in increasing the CVR recording time, and in any event a lot will be gleaned from the flight data recorder....but pulling recorder CBs in flight?
Let's say an engine goes pop as it did in this case, the issue is contained OK initially and a decision is made to pull the CVR.....since the CVR was stopped we now have a well preserved record from the cruise of a thump, somebody calling for a severe damage separation checklist, a bit of T-DODAR....and then nothing....no record of any subsequent analysis done by the crew, any reassessments during the descent, any descent/approach briefing, any conversation/comments made during the approach.
There certainly seems to value in increasing the CVR recording time, and in any event a lot will be gleaned from the flight data recorder....but pulling recorder CBs in flight?
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From the Twitter image linked by tricityb in post #175, it appears that 8 bolt holes are obstructed (bolts sheared off?) while 16 holes appear empty. The largest sector of empty bolt holes spans 120 degrees.
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It's bolts first for me, if it had been hub then the fan would have lost its drive and slowed down.
So it's a fan - IP drum bolt failure leading to an unloading and extreme imblance of the LP/IP system causing overspeed and subsequent fan hub failure before the LP Turb entangles.
We shall see...........disastrous for GP powered A380s, less so if it's a maintenance error (wrong bolts, insuficient torque, wrong anti-seize, rogue parts etc).
So it's a fan - IP drum bolt failure leading to an unloading and extreme imblance of the LP/IP system causing overspeed and subsequent fan hub failure before the LP Turb entangles.
We shall see...........disastrous for GP powered A380s, less so if it's a maintenance error (wrong bolts, insuficient torque, wrong anti-seize, rogue parts etc).
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The section you have indicated does not rotate ...