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SWA1380 - diversion to KPHL after engine event

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SWA1380 - diversion to KPHL after engine event

Old 19th Apr 2018, 17:02
  #261 (permalink)  
 
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For some reason, I don't think Southwest pilots have to worry too much about ICAO R/T procedures.
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Old 19th Apr 2018, 17:03
  #262 (permalink)  
 
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Originally Posted by aliwyatt View Post
It can be seen that a minor amendment to the certification requirement may relieve the interference of multiple aural alerts expressed by "Good Business Sense"


"b. Multiple Aural Alerts
(1) Aural alerts should be prioritised so that only one aural alert is presented at a time. If more than one
aural alert needs to be presented at a time, each alert must be clearly distinguishable and intelligible by the flight
crew (CS 25.1322(a)(2)).
(2) When aural alerts are provided, an active aural alert should finish before another aural alert begins.
However, active aural alerts must be interrupted by alerts from higher urgency levels if the delay to annunciate the
higher-priority alert impacts the timely response of the flight crew (CS 25.1301(a)). If the condition that triggered the
interrupted alert is still active, that alert may be repeated once the higher-urgency alert is completed. If more than
one aural alert requires immediate awareness and the interrupted alert(s) affects the safe operation of the
aeroplane, an effective alternative means of presenting the alert to the flight crew must be provided to meet the
requirements of CS 25.1322(a)(1) and (a)(2)."
That sounds well and good for someone writing a spec. But now imagine you have several high urgency aural alerts. The effect is one continual stream of aural alerts and their visual counterparts just as your piloting skills are being tested by the failures the alerts are repeating to you. It is a human factors nightmare.
The aural sense is actually the first to be suppressed when under stress, so all the aural alerts may do is increase the stress to a level at which they are ineffective.
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Old 19th Apr 2018, 17:36
  #263 (permalink)  
 
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Originally Posted by megan View Post
Sure, I listen to the brief.

There was mention on another forum that the oxygen from these masks tends to stink and that this might be a reason for the masks just covering the mouth. It was also mentioned that because FAs never place the mask physically on their face it can appear to passengers that it just needs to be put over the mouth.


For those that bother to read the emergency card it's obviously quite clear how the mask should be positioned but sadly we know that not everyone does that. Without personal experience I can't comment on whether or the oxygen smells and if so how much. Anyone have personal experience they can share?
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Old 19th Apr 2018, 17:58
  #264 (permalink)  
 
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Smelly O2

>>> . . .whether or the oxygen smells. . .

The oxygen doesn't smell, but it is released from an "oxygen sponge" of (mostly) sodium chlorate in a chemical reaction that heats the NaCl03. The system creates a lot of heat (circa 250įC) in the overhead and things often smell like burning. . . things.

Google "chemical oxygen generator."
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Old 19th Apr 2018, 18:43
  #265 (permalink)  
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If you think the masks issue is being laboured in here, not it has reached mainstream Southwest Airlines emergency sparks on-board safety warnings - BBC News

You can be sure that no briefing is going to warn about the burning smell! Perhaps, during an emergency descent, when reassuring pax, the CC might explain WHY the sudden reduction in altitude and that any other smell you can detect = Don't Panic!
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Old 19th Apr 2018, 19:06
  #266 (permalink)  
 
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If you think the masks issue is being laboured in here, not it has reached mainstream Southwest Airlines emergency sparks on-board safety warnings - BBC News
That article was posted earlier but has been deleted.

Edited to say that the biggest inaccuracy - about masks being useful in a fire has now been edited out of the BBC article.
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Old 19th Apr 2018, 19:25
  #267 (permalink)  
 
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I would think that loss of a fan blade under these conditions would suggest a chaotic exit for the blade mass... I have no difficulty imagining the blade in any or all of several postures post separation from the disc. The dove tail (pine tree) would be susceptible to “rocking” in normal use, forward in Thrust, and backward in windmill. I doubt the dove tail failed evenly in an instant, it would be unlikely the joint let go evenly across its attachment joint. If the failure originated in the rear of the joint, the blade would immediately try to unpeel forward causing the tip to migrate well ahead of the fan’s plane, perhaps explaining the lack of evidence of major contact damage to the blades bracketing it?

Wouldn't the blade accelerate forward, rapidly, as a reaction to loss of attachment? (Newton #3)? Contacting the containing ring (likely it’s first point of contact) it would react violently to interruption of its linear escape, and likely start to wobble intensely? From the reasonably crisp remnants of the cowl, it looks like the blade lingered, radially, at least long enough to trim the honeycomb back to solid metal (Kevlar?).

It would be most interesting to see what remains of the disc pine tree? My conclusion is that the blade left the axis of the engine’s shaft rapidly, but retained some radial trail. How far forward of the engine’s inlet did it extend before traveling aft?
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Old 19th Apr 2018, 20:22
  #268 (permalink)  
 
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There is now a rapid inspection regime. The CFM56 has been in volume production for some 35 years now, so I wonder why it is only now that an event which requires a campaign check has come to light.

Rubber jungle is not only accompanied by the smell from the oxygen generators. I've more than once seen pax describe to the media that the masks were "old and dusty". Nobody had explained that the "dust" is actually french chalk, which engineers pack them with to minimise any snagging on deployment.
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Old 19th Apr 2018, 20:36
  #269 (permalink)  
 
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There is now a rapid inspection regime. The CFM56 has been in volume production for some 35 years now, so I wonder why it is only now that an event which requires a campaign check has come to light.
There are differences between the fans of the different marks of the CFM56 (the 737 NG is the -7, previous 737s were -3, the A320 is -5, and those used to re-engine KC-135s and DC-8s were the -2). Furthermore, according to one write-up, the event engine had 40,000 cycles, 10,000 since overhaul (I'm a bit suspicious - 40k cycles would be a huge amount - I wonder if that's hours not cycles). At any rate it's a very high time engine, so it seems likely that we're looking at a wear-out mode - which may be unique to the CFM56-7 model.
At any rate the FAA has some explaining to do regarding why it's been sitting on a planned fan blade inspection AD for 8 months...
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Old 19th Apr 2018, 20:38
  #270 (permalink)  
 
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No aviator or engineer (as will be obvious...), but the discussions on the trajectory of the errant blade & the differences between static testing & real world blade loss are quite interesting.

On a static test stand the engine will be consuming air that has a density of 1.22 Kg/M3, at FL320 its about 0.41 Kg/M3 - assuming that the engine consumes the same volume at the intake regardless of altitude, does density not play a part in the forces acting upon the fan & if it does would this not make a forward blade trajectory more likely at altitude as there is less mass of air forcing the blade rearwards?

If there is any truth in that, the fact that the static engine is operating in still air & the flying engine operating in a 400kn+ airflow must also play a part - possibly to the extent that it completely cancels the above idea & then some.

Please excuse if this is utter nonsense
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Old 19th Apr 2018, 20:39
  #271 (permalink)  
 
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Switch to a discrete frequency? ATC can't just invent a frequency. How about 121.5 mHz? You know, the International Distress Frequency? Perhaps the air traffic controller didn't even have that frequency at his/her disposal. "Silence, Mayday" could have been imposed, where all non-essential traffic shut up. Clearly these ideas have become obsolete.
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Old 19th Apr 2018, 21:04
  #272 (permalink)  
 
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Originally Posted by Concours77 View Post
... If the failure originated in the rear of the joint, the blade would immediately try to unpeel forward causing the tip to migrate well ahead of the fanís plane, perhaps explaining the lack of evidence of major contact damage to the blades bracketing it?
...
I believe in one of the NTSB briefings it was said that the crack was at the rear and would not have been possible to see on a visual inspection from the front (I think it was in Q&A and that was the question). At some point after separation we know the blade itself fractured into at least two pieces - because the NTSB have the root half but not the rest - but what caused that we can only guess. I doubt it was impact with the rest of the fan because (as you say) what we've seen shows surprisingly little damage there.
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Old 19th Apr 2018, 21:04
  #273 (permalink)  

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For some reason, I don't think Southwest pilots have to worry too much about ICAO R/T procedures.
Agreed, but I believe some American airlines do fly into the UK? I could be wrong, of course.
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Old 19th Apr 2018, 21:35
  #274 (permalink)  
 
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WTF!!!....frikken ambulance chasers at it already...

https://www.usatoday.com/story/news/...eal/531537002/

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Old 19th Apr 2018, 22:13
  #275 (permalink)  
 
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I believe in one of the NTSB briefings it was said that the crack was at the rear and would not have been possible to see on a visual inspection from the front (I think it was in Q&A and that was the question).
Actually, what he said was that the crack was found to be in the interior of the blade. This was in Sumwalt's briefing yesterday afternoon (post 250), at about the 20:00 min mark. He rolled up a piece of paper and pointed inside the tube to show that it wasn't something that would be spotted in a simple visual inspection.
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Old 19th Apr 2018, 23:29
  #276 (permalink)  
 
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Originally Posted by RodH View Post
Why did the Capt. not simply give a mayday call as it was most appropriate.
Because she felt it was not needed. If you listen to the ATC recordings, she stayed exactly within the limits of her authority without getting "trigger happy".

She initiated her descent and subsequently informed the controller (aviate, navigate, communicate). By doing that she used her authority provided by 14 CFR 91.3b, and exactly by that rule: she only deviated from her previous clearance to the extent necessary (emergency descent).

She then asked for directions to the nearest suitable airport. At that point, the controller was perfectly aware of the situation and there really was no need to explicitly declare an emergency.

But, even so: if needed a controller can "declare an emergency" for you. In reality it was not needed, since no rules needed to be breached. If, for example, she had to fly through restricted airspace to get to the runway, then explicitly declaring an emergency may have made sense. But even in that case: no FAA official is going to question her actions.

You declare an emergency to get the attention you need. If you already have the attention, it's just a waste of brain cycles and precious communication time.
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Old 20th Apr 2018, 00:08
  #277 (permalink)  
 
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Originally Posted by tdracer View Post
There are differences between the fans of the different marks of the CFM56 (the 737 NG is the -7, previous 737s were -3, the A320 is -5, and those used to re-engine KC-135s and DC-8s were the -2). Furthermore, according to one write-up, the event engine had 40,000 cycles, 10,000 since overhaul (I'm a bit suspicious - 40k cycles would be a huge amount - I wonder if that's hours not cycles). At any rate it's a very high time engine, so it seems likely that we're looking at a wear-out mode - which may be unique to the CFM56-7 model.
At any rate the FAA has some explaining to do regarding why it's been sitting on a planned fan blade inspection AD for 8 months...
It appears the fan blades can be removed from the disc without greatly dismantling the engine while on the wing, can the blades be crack checked this way.
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Old 20th Apr 2018, 00:53
  #278 (permalink)  
 
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Originally Posted by ph-sbe View Post

You declare an emergency to get the attention you need. If you already have the attention, it's just a waste of brain cycles and precious communication time.
Disagree. Two engine inop approach on 727 for example.
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Old 20th Apr 2018, 01:11
  #279 (permalink)  
 
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Originally Posted by Matt48 View Post
It appears the fan blades can be removed from the disc without greatly dismantling the engine while on the wing, can the blades be crack checked this way.
Short answer is YES. There are some minor complications - for example you want to number the blades and put them all back in the exact same position (otherwise you'll foul up the fan balance), but the fan blades can be readily removed, inspected (probably eddy current), and replaced in a few hours.
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Old 20th Apr 2018, 01:38
  #280 (permalink)  
 
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Thanks TDR. !
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