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United B777 engine failure

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United B777 engine failure

Old 24th Feb 2021, 14:54
  #221 (permalink)  
 
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DaveReidUK

Probably because that's the part description as per the drawing as well as what's in the engine/overhaul manual.

The PW4000 series is a 2 spool engine with a fan (LPC 1) and 4, 5, 6 or 7 additional LPC stages depending on model:




Historically LPC blades have been labelled with the fan being number 1. Not sure if that's the case with modern high bypass ratio engines, but it makes sense.
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Old 24th Feb 2021, 17:09
  #222 (permalink)  
 
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The confidence of the flying public always is a background factor, at least, in how safety incidents are handled. In this time of repressed demand for air travel, and aftermath of debacles with Boeing MAX (and other bad news about another type), perception of the traveling public can be interesting thing to watch, to an SLF/atty anyway.

So reading a good solid reporting piece in the Wall Street Journal today, by-line of Alison Sider, with headline, "Probes of Faulty Jet Engine Intensify" yields some confidence that despite other sources of less reliable repute, there is some good reporting out there. Article covers relation of past incidents to the current one, as well as good laypeople's explanation of some of the operational or design characteristics involved.
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Old 24th Feb 2021, 17:42
  #223 (permalink)  
 
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iranu

"Historically LPC blades have been labelled with the fan being number 1. Not sure if that's the case with modern high bypass ratio engines, but it makes sense."

Correct - I asked the FAA earlier today and this was the response:

"1st-stage LPC compressor blade" is what P&W uses to refer to their fan blade. I am required to use the nomenclature P&W uses in their engine manual (EM) and service bulletins (SB) for all ADs that are written. This is mainly because the maintenance personnel will use the EM and SB to accomplish the AD. Using fan blade in the AD would cause confusion.
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Old 24th Feb 2021, 18:31
  #224 (permalink)  
 
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This seems to be the fifth time this has occured.

see,

https://en.wikipedia.org/wiki/Pratt_%26_Whitney_PW4000
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Old 24th Feb 2021, 18:46
  #225 (permalink)  
 
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Two of those five incidents were not fan failures, so it's not clear what you mean by "the fifth time this has occurred".
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Old 24th Feb 2021, 19:21
  #226 (permalink)  
 
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Perhaps even 3 are cause for concern.

see:
1) left engine, PW4098-112 engine suffered an uncontained failure

2) 45 minutes before landing, suffered a fan blade failure, which caused much of the inlet and cowl to separate from the engine.

3) left hand engine (PW4074) failed and its access doors ripped of
also see "The ministry reported one of the fan blades of the left hand engine was damaged at the root". from the source https://avherald.com/h?article=4e011c3a

4) On February 20, 2021, a Boeing 777-200 with PW4077-112 engines performing United Airlines Flight 328 from Denver to Honolulu suffered a fan blade failure shortly after takeoff

5) engine failure above the village of Meerssen, shortly after taking off from Maastricht Aachen Airport on the way to John F. Kennedy International Airport. Falling turbine blades lightly injured two persons on the ground.
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Old 24th Feb 2021, 20:51
  #227 (permalink)  
 
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Compressor stage numbering:-
In pre-bypass days, RR would sometimes stick a 0 stage on the front, and even a 00 stage in front of that.
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Old 25th Feb 2021, 02:47
  #228 (permalink)  
 
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Originally Posted by N707ZS
If the parts land on your property are they still the property of the airline.
If memory serves me correctly, this is may be a weird and ancient corner of real estate law: If fruit from your neighbor's tree falls onto your property, you can't eat it, but then again you aren't obligated to let your neighbor onto the property to retrieve it, either.
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Old 25th Feb 2021, 13:51
  #229 (permalink)  
 
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Boeing Moved to Replace 777 Engine Covers Before Recent Failures - Wall Street Journal:

First few paragraphs of article (by-line Andrew Tangel and Alison Sider):
_________________
Boeing was planning to strengthen protective engine covers on its 777 jets months before a pair of recent serious failures, including one near Denver last weekend, according to an internal Federal Aviation Administration document.

The plane maker and regulator had been discussing potential fixes even longer—for about two years, according to people familiar with the matter. The talks began after two failures in 2018, one on a 777 operated by United Airlines Holdings Inc. and the other on a Southwest Airlines Co. 737.

Because potential modifications to 777 external engine covers, commonly known as cowlings, had various shortcomings, “Boeing has decided to redesign the fan cowl instead of trying to modify existing fan cowls to address both the structural strength concerns” and moisture issues, according to the internal FAA document reviewed by The Wall Street Journal.

“Boeing will be manufacturing new fan cowls and providing service instructions for operators to remove and replace the fan cowls,” according to the document, part of a routine Aug. 6, 2020, update on efforts under way at the agency’s Seattle-area offices. Boeing and the FAA declined to comment on the engine-cover plan’s status Wednesday.
_____________________

No clue on where or how the internal document emerged.... an interesting set of issues in and about FAA to greet the new Secretary of DOT, methinks.
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Old 25th Feb 2021, 14:14
  #230 (permalink)  
 
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Lomon

Well spoken. The atc controller has also to get all the hospitals on standby based on the number; they do not all create a crater
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Old 25th Feb 2021, 14:32
  #231 (permalink)  
 
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Good Response, ATC aren't asking these questions to make you're life more difficult! Admittedly trying to find the right time to ask these questions is a problem.
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Old 26th Feb 2021, 11:48
  #232 (permalink)  
 
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Some first hand knowledge here. In some cases the suspected owner denies ownership ( few hundred pound piece found in woods, never claimed) Seems to match the maintenance reports that get filed months later of parts missing upon walk-round before next flight
A few cases where new owner demanded significant money for parts that fell before giving them back. Problem solved by immediate confiscation by the likes of the NTSB et.al. Not sure about new owner reusing the parts as long as they meet all air-regulations. One guy simply displayed the parts (fell off a truck0 in his front yard for all to see that he was within his rights.
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Old 26th Feb 2021, 15:56
  #233 (permalink)  
 
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WillowRun 6-3

Are Boeing (or Airbus for that matter) actually responsible for engines manufactured by Pratt and Whitney, Rolls Royce, GE, CFM International etc?
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Old 26th Feb 2021, 16:18
  #234 (permalink)  
 
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best to define your interpretation of "responsible"
Each side is responsible to the regulator for meeting their side of providing safety

come to think of it I've never heard of an engine getting grounded, but only the plane

TD ought to be able to add some wisdom here
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Old 26th Feb 2021, 16:46
  #235 (permalink)  
 
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It depends. The engines are the responsibility of the engine manufacturer, but the actual cowling (nacelle) can either be done by the airframer, outsourced, or sourced from the engine manufacturer.
On the 777, Boeing did most of the nacelle in-house for all three engine types. On the 787, nearly all the nacelle was outsourced (which didn't go very well). On the 747-8, the nacelle was something of a joint venture between Boeing and GE (Middle River).
But the specific mater in hand - the PW4000/112" engine as installed on the 777 - Boeing did the nacelle.
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Old 26th Feb 2021, 16:53
  #236 (permalink)  
 
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Boeing owns the type design and was the pt 25 certification applicant. The type design includes installation of the particular engine. So Boeing certainly has responsibility from nose to tail and wingtip to wingtip. The engine manufacturer also had its engine type design certified under cognizant regulations and also has responsibility.
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Old 26th Feb 2021, 17:54
  #237 (permalink)  
 
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So the media are into their usual frenzy I see. Headlines everywhere about a B777 emergency landing at Moscow due to an "engine sensor problem".

They sort of mention halfway down their articles that it was a GE engine mind you.
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Old 26th Feb 2021, 19:12
  #238 (permalink)  
 
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3D printed parts

I recently watched with interest an item showing very high tolerance metal parts being formed by a "3D Printer" that did away with the the injection mould method that was used on these hollow fan blades that failed in this thread discussion.

Are there any engineers that can comment on this process that could or are being used in the aerospace industry, and may be attending the AM Industry Summit below?


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Old 26th Feb 2021, 19:52
  #239 (permalink)  
 
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Can't comment on these kinds of parts in Aerospace industry but Porsche are using this 3D printing technique.
They have been re-manufacturing parts that have been out of stock for a long time and for which the original tooling is worn out.
Such parts include clutch-operating levers and even pistons for their top sport models using, IIRC 'adaptive-laser-fusion' tech both of which would be high-stress parts, so I can't see why fan blades would be too far of a stretch .
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Old 26th Feb 2021, 20:34
  #240 (permalink)  
 
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From the NTSB Powerplants Group Chairman's Factual Report, UAL 1175, https://data.ntsb.gov/Docket/?NTSBNumber=DCA18IA092

"The PW4000 112-inch fan blade has a hollow core airfoil. The blade is made from two titanium-alloy flat plates that have the airfoil’s external and internal features machined out. The airfoil halves then undergo dimensional and material inspections prior to being bonded together. The bonded halves undergo further machining and another material inspection prior to being formed into the fan blade’s final shape. After the blade is formed into the final shape, the blade’s root is machined as are the leading and trailing edges and the blade tip. The blade then undergoes a visual and another material inspection before undergoing several surface finish treatments. The blade then undergoes a dimensional inspection and a final inspection."

Not a very good or complete description , but apparently diffusion bonded and superplastic formed.
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