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View Full Version : JAL B772 at Okinawa - Dec 4th 2020


Zeffy
5th Dec 2020, 01:20
Incident: JAL B772 at Okinawa on Dec 4th 2020, engine shut down in flight after uncontained failure, parts of engine cowl dropped (http://avherald.com/h?article=4e011c3a&opt=0)

https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/750x563/jal_b772_ja8978_okinawa_201204_1_b54f6d0a3bf38dd79a5415ddc48 38fd1ea02b067.jpg

WillFlyForCheese
5th Dec 2020, 01:49
Uncontained failure? Any chance that cover became dislodged/open when the fan blade broke loose and simply departed the aircraft? It almost looks too clean to be an uncontained failure.

Dave Therhino
5th Dec 2020, 03:16
It was not an uncontained failure. It was a contained fan blade failure. It caused the fan cowl doors to fail, which isn't supposed to happen.

tdracer
5th Dec 2020, 05:10
Yea, but better than the inlet coming off...
Refresh my memory - what engines does JAL have on their 777-200s?
I'm sure I knew at one time, but like the say, the memory is the second thing to go - I forget what was first :E

KelvinD
5th Dec 2020, 05:51
They have GE & PW engines. This one had the PW4084

DaveReidUK
5th Dec 2020, 07:44
Dave Therhino

Indeed. "Uncontained" has a specific meaning in the context of engine failures. It doesn't include fan blade (or even turbine blade) parts ejected out of the front or back of the engine.

Sloppy reporting, or maybe lost in translation.

lomapaseo
5th Dec 2020, 12:04
More like simplified reporting presuming details to follow days later.

Engines are certified contained without the coverings around them that are supplied by the installer. The first concern is whether high energy parts were ejected to threaten other aircraft systems.

It's up to the investigation to determine this and who fixes what as necessary

No surprise that soft stuff like kevlar belts surrounding a fan blade might deflect into any nacelle coverings. (same thing happens in body armour ouch!)

Whinging Tinny
5th Dec 2020, 14:54
This will give you a better idea of the damage caused:

https://www.youtube.com/watch?v=0LxlwUFjJG8

Austrian Simon
8th Dec 2020, 11:13
DaveReidUK

The JTSB have just confirmed debris penetrated the engine casing (in other words, debris exited the engine radially, the very definition of an uncontained engine failure).

Sloppy reporting, eh?

DaveReidUK
8th Dec 2020, 14:05
I stand by my comment.

Clue: SWA1380 wasn't an "uncontained engine failure" either, despite the fact that some sources continue to report it as such. :ugh:

Accident: Southwest B737 near Philadelphia on Apr 17th 2018, uncontained engine failure takes out passenger window (https://avherald.com/h?article=4b7725fb&opt=0)

lomapaseo
8th Dec 2020, 15:12
Austrian Simon

Can you provide the wording from the investigation? e.g were other aircraft systems penetrated by engine debris? Obviously the details about the engine-pod fan cowls are probably still being evaluated

Austrian Simon
8th Dec 2020, 16:11
DaveReidUK

It is interesting to note, that you immediately jump to another occurrence in trying to evade this very clear statement by the JTSB, that they are investigating a "situation similiar to damage to an engine (when debris penetrates the case of the engine)". Such a tactics is an immediate admission that you are out of arguments and your statement/assumption was wrong.

In your yearlong crusade you overlook the obvious: WN-1380 was an uncontained failure, too, despite the fan containment ring not having been penetrated though having suffered a breach. Even though the NTSB was very careful in their wording and never described the event as contained or uncontained engine failure, their analysis makes clear, blade fragments exited radially before the containment ring at WN-1380 causing significant damage to the engine inlet, when they wrote:"One difference was that the fan blade fragments that went forward of the fan case and into the inlet during the accident FBO event had a different trajectory (a larger exit angle) and traveled beyond the containment shield. Another difference was that the inlet damage caused by these fan blade fragments was significantly greater than the amount of damage that was defined at the time of inlet certification."

A very similiar event to WN-1380 with almost identical damage to engine containment ring and inlet, WN-3472 of Aug 27th 2016, was clearly called an "uncontained engine failure" by the NTSB. In addition, FAA and EASA both called that event of 2016 an uncontained release of debris in their resulting airworthiness directives stating: "An occurrence was reported of fan blade failure on a CFM56-7B engine. The released fan blade was initially contained by the engine case, but there was subsequent uncontained forward release of debris and separation of the inlet cowl."

In the EAD 2018-09-51 (tel:2018-09-51) following the 2018 engine failure the FAA wrote 3 days after the accident:

"This emergency AD was prompted by a recent event in which a Boeing Model 737-700 airplane powered by CFM56-7B model engines experienced an engine failure due to a fractured fan blade, resulting in the engine inlet cowl disintegrating. Debris penetrated the fuselage causing a loss of pressurization and prompting an emergency descent. Although the airplane landed safely, there was one passenger fatality. Fan blade failure due to cracking, if not addressed, could result in an engine in-flight shutdown (IFSD), uncontained release of debris, damage to the engine, damage to the airplane, and possible airplane decompression."

lomapaseo
8th Dec 2020, 18:51
Austrian Simon

I await your answer to my request above.

As always the importance of an investigation is the recommendations for corrective actions whether they be at the design level, maintenance, training. or operation levels. Semantics is only important when searching for codified regulatory material.

DaveReidUK
8th Dec 2020, 19:04
Austrian Simon

On the contrary, simply pointing out that it wouldn't be the first time you have mis-categorised an engine failure as "uncontained".

You are a great journalist, Simon, when it comes to reporting facts, so I'd suggest that you content yourself with that, until such time as you can report on the findings of the investigation.

If you're determined to subject the incident to "analysis" in the meantime, you might want to reflect on the fact that the media coverage shows the engine from pretty well every angle.

If a blade, or part of one, was ejected radially, it appears to have managed to do so without making any discernable hole in the nacelle. The statement that you quote from the JTSB doesn't support your assertion that it was an uncontained failure.

Austrian Simon
8th Dec 2020, 19:22
lomapaseo

I actually included that information in my earlier post (and in the article): The JTSB reported they investigate a "situation similiar to damage to an engine (when debris penetrates the case of the engine)". They did not specify any more details yet, it is just the notification of investigation being opened.

lomapaseo
9th Dec 2020, 03:12
OK that makes sense, there is a lot to see here and assess.

Dave Therhino
10th Dec 2020, 04:07
The recent 777 event, Southwest 1380, and Southwest 3472 all were not uncontained failures as defined by industry and the regulatory authorities. The initial NTSB press releases for 3472 incorrectly used the term "uncontained" (as does Wikipedia), but if you read the subsequent NTSB accident report for 1380 in the section on previous incidents they state the fan blade in the 3472 event did not breach the containment ring or the debris shield that was part of the inlet inner wall structure, and they do not use the term "uncontained" in that later summary of the 3472 event.

https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1903.pdf
(see page 60)

DaveReidUK
10th Dec 2020, 08:55
The recent 777 event, Southwest 1380, and Southwest 3472 all were not uncontained failures as defined by industry and the regulatory authorities.

Yes, the generally accepted definition is contained in FAA Advisory Circular AC 33-5: Turbine Engine Rotor Blade Containment/Durability (https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_33-5.pdf), dating from 1990:

"Contained means that no fragments are released through the engine structure, but fragments may be ejected out the engine air inlet or exhaust."

(note the specific reference to blades)

Recommended reading for all. :O

Austrian Simon
10th Dec 2020, 18:15
Actually, WN-3472 (Aug 24th 2016) final report states the engine failure was uncontained (looks like this final report has escaped my attention so far) :

http://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/93897/pdf

Quote: "Defining Event: Uncontained engine failure"

This is not being used for WN-1380 (Apr 17th 2018), the NTSB does not state in that final report, whether the engine failure was contained or uncontained at all.

However the investigation's powerplant group spent a whole lot of time and many, many, many pages in their report about those definitions/interpretations in the FAA regulations and advisory circulars:

FAR Section 33.19:

FAR Section 33.19 requires the engine manufacturer (CFM in this case) “…design of the compressor and turbine rotor cases must provide for the containment of damage from rotor blade failure.’’ Although not stated specifically, historically this has been interpreted that engine debris cannot penetrate and pass radially through any of the engine cases, but debris can exit axially out the front or back of the engine. FAR Section 33.19 also addresses engine debris exiting out the front and back of the engine by requiring that “… Energy levels and trajectories of fragments resulting from rotor blade failure that lie outside the compressor and turbine rotor cases must be defined.”

AC 33-5:

According to AC 33-5 ‘contained’ was defined to mean “that no fragments are released through the engine structure, but fragments may be ejected out of the engine air inlet or exhaust” and defined ‘engine structure’ to mean “the engine structure surrounding the main rotors and extending from the forward-most case flange through the rear most flange, as defined by the type design”.

AC 20-128:

For the purposes of airplane evaluations in accordance with this AC, uncontained failure of a turbine engine is any failure which results in the escape of rotor fragments from the engine or APU that could result in a hazard. Rotor failures which are of a concern are those where released fragments have sufficient energy to create a hazard to the airplane.

I am still investigating and engaged in a background research over this discussion to clarify the real definition of contained and uncontained on regulatory level (seeing those three different conflicting interpretations). The question now is: why is the one occurrence rated uncontained, and the other very similair event not categorized in that respect?

Applying the historical definition based on FAR 33.19 the engine failure of WN-1380 needs to be categorized as uncontained just like WN-3472. Applying AC 20-128 or AC 33-5 neither event is uncontained.

Checkboard
10th Dec 2020, 20:45
Although not stated specifically, historically this has been interpreted that engine debris cannot penetrate and pass radially through any of the engine cases, but debris can exit axially out the front or back of the engine.
Of course the point of all this is that blades exiting radially threaten the cabin, the fuel tanks and the hydraulic and electric control runs in the wings.

Bits of engine exiting forward or backward don't. They fall behind the aircraft in flight.

That's why the distinction is important.

DaveReidUK
10th Dec 2020, 21:47
The initial NTSB press releases for 3472 incorrectly used the term "uncontained" (as does Wikipedia), but if you read the subsequent NTSB accident report for 1380 in the section on previous incidents they state the fan blade in the 3472 event did not breach the containment ring or the debris shield that was part of the inlet inner wall structure, and they do not use the term "uncontained" in that later summary of the 3472 event.

Not only is it referred to in the later SWA1380 report, but it's also stated explicitly in the SWA3472 Final Report that Simon kindly supplied a link to (above):

"The fan case had no through-hole penetrations and showed no evidence of an uncontainment [sic]". (P16)

armagnac2010
10th Dec 2020, 21:51
Please be carefull in comparing engine and aircraft certification material. They serve different purposes and might be inconsistent if taken out of their context.

At engine level, uncontained failure is typically associated with casing performation. The engine certification cannot assess installation effects. On this basis, SWA is not an uncontained engine failure, from the strict engine point of view.

At aircraft level, not so. EASA AMC 20-128A and FAA AC 20-128A, which are identical, provide an engine failure model, based upon historical data, which includes fan blade fragments with a spread angle reaching up to 15 of the nominal rotation plan (9.e). Typically, this addresses fan blades released forward of the fan containment system, exactly as in the case of SWA1380. The SWA1380 event is an uncontained failure engine failure. .

And bearing in mind that from a safety point of view, what really matters is the aircraft and not the engine, it is fair to conclude we can consider the event as uncontained engine failure.

lomapaseo
11th Dec 2020, 01:26
DaveReidUK

Yes, and I participated in drafting the AC in both the engine and airframe regs. I wrote the strawman summary words and the lawyers and wordsmithers altered them to their satisfaction. I take no other ownership other than the intent to clarify and improve safety of flight. I still feel they guide the investigator's findings in creating specific areas under continued airworthiness against which to write recommendations..

I can tell you that the doers don't have a problem in applying corrective action against the design intent. Thus I see no benefit in continuing this wordsmith debate

jolihokistix
11th Dec 2020, 04:52
Having read through all the posts so far, it seems that each reference to 'fragments' is confusingly ambiguous, at times meaning engine fragments, at others fan/rotor blade fragments, but it is often open to interpretation, i.e. not made clear which is meant.

DaveReidUK
11th Dec 2020, 06:58
Not really. The 13 references to "fragments" in the thread so far (prior to your post) all make it clear that they refer to blade/rotor fragments, i.e. the rotating components of an engine. I can't see any ambiguity.

Thus I see no benefit in continuing this wordsmith debate

Yes, I think we've got to the stage (npi) where we're stretching semantics beyond its elastic limit - one is reminded of Humpty Dumpty's (https://www.goodreads.com/quotes/12608-when-i-use-a-word-humpty-dumpty-said-in-rather) famous saying. :O

Getting back on topic to the subject of the thread, it now seems clear that there's no evidence so far to support the proposition that any part of the two damaged fan blades on the JAL 777 exited by penetrating the fan case.

Whinging Tinny
11th Dec 2020, 14:59
Austrian Simon

Please show me and everyone else where in the JSTB report stating they have opened an investigation, they say the words you posted in brackets.

Also, look up the definition of penetration.

I'd suggest you don't use an automatic translator, copy and paste especially with a language like Japanese as well.
Do you feel free to post your reply in Japanese if you wish.

Austrian Simon
11th Dec 2020, 16:24
The original is at: Investigation Notification JA8978 (https://jtsb.mlit.go.jp/jtsb/aircraft/detail2.php?id=2285)

If you doubt the translation of that note's type of occurrence, here is the English translation by the JTSB themselves out of older already completed accident reports, with exactly the same Japanese categorization ("発動機の破損(破片が当該発動機のケースを貫通した場合に限る。)に準ずる事態"): "Damage of engine (limited to such a case where fragments penetrated the casing of subject engine)"

BTW, the JTSB uses the word penetration as the part going through the hole, as several already released English final reports make clear.

DaveReidUK
11th Dec 2020, 18:37
Full text of the JTSB Accident/Incident Categorization under which this event will be investigated:

https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/1113x68/jtsb_categorizations_2_361dcfd5d32723ed7488c059b94501b6b8628 0e4.jpg

(per Ordinance for Enforcement of the Civil Aeronautics Act, Article 166-4 (https://vdocuments.net/chapter-2-aircraft-accident-and-serious-incident-fifteen-investigation-reports.html))

Clearly this categorization encompasses both contained and uncontained failures.

While it's certainly true that recent JTSB engine failure investigations covered by this categorization relate to uncontained failures, that has no bearing on the JAL event - which clearly wasn't, as the investigation report will show in due course.

Austrian Simon
11th Dec 2020, 20:35
Only problem being, that in the actual classification of the occurrence there is no mention of the major damage inside the engine but ONLY the mention of fragments penetrated the casing of the subject engine. You quoted the generic regulativ that mentions all possible types under Article 166-4:

Article 166-4 of the Ordinance for Enforcement of the Civil Aeronautics Act (The case prescribed in the Ordinances of the Ministry of Land, Infrastructure. Transport and Tourism under Article 76-2 of the Civil Aeronautics Act)

1. Take-off from a closed runway or a runway being used by other aircraft or aborted take-off
2. Landing on a closed runway or a runway being used by other aircraft or attempt of landing
3. Overrun, undershoot and deviation from a runway (limited to when an aircraft is disabled to perform taxiing)
4. Case where emergency evacuation was conducted with the use for emergency evacuation slide
5. Case where aircraft crew executed an emergency operation during navigation in order to avoid crash into water or contact on the ground
6. Damage of engine (limited to such a case where fragments penetrated the casing of subject engine or a major damage occurred inside the engine)
7. Continued halt or loss of power or thrust (except when the cngine(s) arc stopped with an attempt of assuming the engine(s) of a motor glider) of engines (in the case of multiple engines, 2 or more engines) in flight
8. Case where any of aircraft propeller, rotary wing, landing gear, rudder, elevator, aileron or flap is damaged and thus flight of the subject aircraft could be continued
9. Multiple malfunctions in one or more systems equipped on aircraft impeding the safe flight of aircraft
10. Occurrence of fire or smoke inside an aircraft and occurrence of fire within an engine fire-prevention area
11. Abnormal decompression inside an aircraft
12. Shortage of fuel requiring urgent measures
13. Case where aircraft operation is impeded by an encounter with air disturbance or other abnormal weather conditions, failure in aircraft equipment, or a flight at a speed exceeding the airspeed limit, limited payload factor limit operating altitude limit
14. Case where aircraft crew became unable to perform services normally due to injury or disease
15. Case where parts dropped from aircraft collided with one or more persons
16. Case equivalent to those listed in the preceding items

As I said, the JTSB themselves translate the exact same Japanese text (in the classification of this occurrence of JA8978) as: "Damage of engine (limited to such a case where fragments penetrated the casing of subject engine)" and do not cite the other option of major engine damage.

Apples and Bananas ...

Again, the Japanese text you quoted: "六 発動機の破損(破片が当該発動機のケースを貫通し、又は発動機の内部において大規模な破損が生じた場合に限る。) translates to: "Damage to the engine (limited to cases where the fragment penetrates the case of the engine or a large-scale damage occurs inside the engine)
The text of the occurrence in comparison: "発動機の破損(破片が当該発動機のケースを貫通した場合に限る。)に準ずる事態" which translates to: " Situations equivalent to damage to the engine (when debris penetrates the case of the engine)" and the JTSB translates this exact phrase: "Damage of engine (limited to such a case where fragments penetrated the casing of subject engine)"

Pilot DAR
12th Dec 2020, 17:52
Posters, please play the ball, not the player....