Quite an uncontained engine failure
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This is a clear case of inner barrel of nose cowl (usually carbon fiber) failure. I have seen such a failure on RR engine. It occurs during takeoff thrust when the engine suction is highest. Once a small portion liberates from inner barrel, within no time the rest of the inner barrel and outer barrel fails due high suction produced by fan. On most aircraft it is a turnaround inspection item, to check inner barrel for any surface damage. Engineers are not supposed to stand or sit on the inner barrel for any maintenance work without a protective mat. This is applicable to most modern engines that have carbon fiber honey comb panels in the intake. Just an observation from my experience. Could be other reasons as well,
Psychophysiological entity
Interesting. In all these years I've not pondered the differential pressure across the sides of the intake.
They were perhaps still in the climb at 30k' before maximum ram air.
Given the 777 gulps a tonne of air a second in the cruise, I'd not be surprised if this wasn't a major factor.
So, all those pretty girls standing in engines for promotional photos have heel protectors?.
They were perhaps still in the climb at 30k' before maximum ram air.
Given the 777 gulps a tonne of air a second in the cruise, I'd not be surprised if this wasn't a major factor.
So, all those pretty girls standing in engines for promotional photos have heel protectors?.
Last edited by Loose rivets; 29th Aug 2016 at 11:35.
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Recent flight on a humid day I was sitting just forward of the intake. It was fascinating to see a low pressure condensation cloud form just in front of- and around the intake. That included a mini-spiral tornado reaching from the ground. Physics is a wonderful subject. I wish I were better at maths.
Did they find any debris on the ground?
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Here is the example of what can happen when intake fails. This one did not disintegrate completely like south west B737. But engine ingested enough debris to cause severe damage. Damage to intake are rare and are usually spotted during turnaround inspection.
http://www.pprune.org/attachment.php...1&d=1472550670
http://www.pprune.org/attachment.php...1&d=1472550670
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My thoughts
I'm thinking a compressor surge as a likely candidate for the cause of the inlet failure. It appears most if not all N1 blades appear intact. No sign of breech in the rotational plane of N1 disc. No visible indication of bird strike. What other force could drive the debris to contact the fuselage and winglet?
sockFAP - "What other force...?" Ram air into the front of the intake. Emphasis on the "RAM."
Like a balloon popping, if the intake loses structural integrity ("comes apart") through fatigue or whatever other fault, the pieces will tend to shoot off in all directions in whatever is the "path of least resistance." With ram air coming in from the front, and a fairly solid chunk of nacelle and engine behind, that path will be mostly sideways.
Think of a plastic or paper cup, mounted at its base onto something solid. Direct a firehose into the open mouth of the cup, and it will fan out sideways as it comes apart.
Like a balloon popping, if the intake loses structural integrity ("comes apart") through fatigue or whatever other fault, the pieces will tend to shoot off in all directions in whatever is the "path of least resistance." With ram air coming in from the front, and a fairly solid chunk of nacelle and engine behind, that path will be mostly sideways.
Think of a plastic or paper cup, mounted at its base onto something solid. Direct a firehose into the open mouth of the cup, and it will fan out sideways as it comes apart.
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hunbet:
(red uniform)
Nope - Fan rotation is opposite of a RR engine. (EDIT
MY BAD! I think my eyeballs have optical reversal!
DaveReidUK below is correct!
In the first picture it is an L1011
Nope - Fan rotation is opposite of a RR engine. (EDIT
MY BAD! I think my eyeballs have optical reversal!DaveReidUK below is correct!
Last edited by barit1; 12th Sep 2016 at 00:50.
What engine? 
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Note the mantion of a fan blade separation
A classic "Chicken and Egg" puzzle. Which came first, the blade separation causing the cowling failure or ..... the cowling failure causing the blade separation?
Investigative Update Provides Initial Findings in Investigation of Uncontained Engine Failure http://www.ntsb.gov/news/press-relea...R20160912.aspx
________________________________________
September 12, 2016
WASHINGTON — As part of its ongoing investigation of an Aug. 27, 2016, uncontained engine failure on Southwest Airlines flight 3472, the National Transportation Safety Board issued an investigative update Monday.
The uncontained engine failure happened on a Boeing 737-700 enroute from New Orleans, Louisiana, to Orlando, Florida. The airplane was diverted to Pensacola International Airport, Pensacola, Florida, and safely landed without further incident.
The investigative update details the NTSB’s initial findings from the examination of the airplane and the engine, and a metallurgical examination.
Initial findings from the examination of the airplane include:
o The left engine inlet separated from the engine during the flight. Debris from the engine inlet damaged the airplane fuselage, wing and empennage,
o A 5-inch by 16-inch hole was found in the left fuselage just above the left wing,
o No fan blade or inlet material was found in the hole and the passenger interior compartment was not penetrated, and
o During the accident sequence, the airplane experienced a cabin depressurization.
o The aircraft maintenance records are being reviewed.
Initial findings from the engine examination include:
o One fan blade separated from the fan disk during the accident flight and
o The root of the separated fan blade remained in the fan hub; however, the remainder of the blade was not recovered.
Initial findings from the metallurgical examination conducted in the NTSB Materials Laboratory include:
o The fracture surface of the missing blade showed curving crack arrest lines consistent with fatigue crack growth. The fatigue crack region was 1.14-inches long and 0.217-inch deep,
o The center of the fatigue origin area was about 2.1 inches aft of the forward face of the blade root. No surface or material anomalies were noted during an examination of the fatigue crack origin using scanning electron microscopy and energy-dispersive x-ray spectroscopy, and
o The blades are manufactured of a titanium alloy and the root contact face is coated with a copper-nickel-indium alloy.
NTSB Senior Aviation Investigator Tim LeBaron, the Investigator-in-Charge, is leading a team with expertise in the areas of airworthiness, powerplants, and metallurgy. The flight data recorder and the cockpit voice recorder were shipped to the NTSB Recorder Laboratory and the data from each were downloaded.
Parties to the investigation include the Federal Aviation Administration, Southwest Airlines the Southwest Airlines Pilots Association, and CFM International. The French Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile has appointed an accredited representative who is supported by a technical advisor from Safran Aircraft Engines. CFM International is a joint venture between GE Aviation [US] and Safran Aircraft Engines [France].
Future work will include 3-D measurements of the contact areas of all the blades, a non-destructive examination of the blade surfaces for cracks, and a review of the engine maintenance records.
The accident docket, containing factual group reports and other investigation-related material, will be opened at a future date. Additional information will be released as warranted.
Investigative Update Provides Initial Findings in Investigation of Uncontained Engine Failure http://www.ntsb.gov/news/press-relea...R20160912.aspx
________________________________________
September 12, 2016
WASHINGTON — As part of its ongoing investigation of an Aug. 27, 2016, uncontained engine failure on Southwest Airlines flight 3472, the National Transportation Safety Board issued an investigative update Monday.
The uncontained engine failure happened on a Boeing 737-700 enroute from New Orleans, Louisiana, to Orlando, Florida. The airplane was diverted to Pensacola International Airport, Pensacola, Florida, and safely landed without further incident.
The investigative update details the NTSB’s initial findings from the examination of the airplane and the engine, and a metallurgical examination.
Initial findings from the examination of the airplane include:
o The left engine inlet separated from the engine during the flight. Debris from the engine inlet damaged the airplane fuselage, wing and empennage,
o A 5-inch by 16-inch hole was found in the left fuselage just above the left wing,
o No fan blade or inlet material was found in the hole and the passenger interior compartment was not penetrated, and
o During the accident sequence, the airplane experienced a cabin depressurization.
o The aircraft maintenance records are being reviewed.
Initial findings from the engine examination include:
o One fan blade separated from the fan disk during the accident flight and
o The root of the separated fan blade remained in the fan hub; however, the remainder of the blade was not recovered.
Initial findings from the metallurgical examination conducted in the NTSB Materials Laboratory include:
o The fracture surface of the missing blade showed curving crack arrest lines consistent with fatigue crack growth. The fatigue crack region was 1.14-inches long and 0.217-inch deep,
o The center of the fatigue origin area was about 2.1 inches aft of the forward face of the blade root. No surface or material anomalies were noted during an examination of the fatigue crack origin using scanning electron microscopy and energy-dispersive x-ray spectroscopy, and
o The blades are manufactured of a titanium alloy and the root contact face is coated with a copper-nickel-indium alloy.
NTSB Senior Aviation Investigator Tim LeBaron, the Investigator-in-Charge, is leading a team with expertise in the areas of airworthiness, powerplants, and metallurgy. The flight data recorder and the cockpit voice recorder were shipped to the NTSB Recorder Laboratory and the data from each were downloaded.
Parties to the investigation include the Federal Aviation Administration, Southwest Airlines the Southwest Airlines Pilots Association, and CFM International. The French Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile has appointed an accredited representative who is supported by a technical advisor from Safran Aircraft Engines. CFM International is a joint venture between GE Aviation [US] and Safran Aircraft Engines [France].
Future work will include 3-D measurements of the contact areas of all the blades, a non-destructive examination of the blade surfaces for cracks, and a review of the engine maintenance records.
The accident docket, containing factual group reports and other investigation-related material, will be opened at a future date. Additional information will be released as warranted.
Last edited by Longtimer; 12th Sep 2016 at 20:56.
Not much of a puzzle with the scrape marks in the inlet if the fan blade pieces traveled across the fractured edges of the cowl.
It did take quite a bit of time to come out with the fact of a missing blade
The rest of the story reverts now to the engine analysis experts and the inlet designers under engine rundown and windmill conditions.
It did take quite a bit of time to come out with the fact of a missing blade
The rest of the story reverts now to the engine analysis experts and the inlet designers under engine rundown and windmill conditions.
See post #21. Officially it did take some time, however, the info was out there
With some sleuthing of pics you could even make out the hole at the bottom of the nacelle.
What gets fixed and how is of the interest now
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ATC Transcript
(Disclaimer: SLF here)
I'm not sure if it is of interest here, but I found a transcription of the ATC communication during the event on Youtube. It's not based on real ATC tapes, just LiveATC recordings, but I think it's interesting.
https://www.youtube.com/watch?v=3mJCI-NCxoI
What do you think?
I'm not sure if it is of interest here, but I found a transcription of the ATC communication during the event on Youtube. It's not based on real ATC tapes, just LiveATC recordings, but I think it's interesting.
https://www.youtube.com/watch?v=3mJCI-NCxoI
What do you think?
