737 Engine comes of wing in Cape Town
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I am told the JT8D weighs 4 tonnes with cowlings and accessory gearbox, etc. That, along with the drag of a seized engine, make it a useful though unintentional jettison. Notwithstanding, it remains undisirable.
Any clever boys and girls got some ideas on the pro's of a 4 tonne instant jettison with gear stuck down (A hyd lost) vs a retracted gear, engine seizure scenario?
This aircraft is (thankfully not WAS) ex LH with smaller -15A engines. Sea level. Max pax with approx 10 tonnes fuel. Looks rainy (cool day), so assume max TO thrust. Bear in mind that with the engine (seized) remaining on scenario, the drag of the gear is still a factor in initial climbout until retracted.
Calling all mathematicians and aeronautical engineers
Impressive flying display, in anyones eyes, well done
.
Any clever boys and girls got some ideas on the pro's of a 4 tonne instant jettison with gear stuck down (A hyd lost) vs a retracted gear, engine seizure scenario?
This aircraft is (thankfully not WAS) ex LH with smaller -15A engines. Sea level. Max pax with approx 10 tonnes fuel. Looks rainy (cool day), so assume max TO thrust. Bear in mind that with the engine (seized) remaining on scenario, the drag of the gear is still a factor in initial climbout until retracted.
Calling all mathematicians and aeronautical engineers
Impressive flying display, in anyones eyes, well done
.
Last edited by fly nice; 9th Nov 2007 at 20:12.
The assumption for now seems to be that the transverse gyroscopic forces of a catastrophic seizure could have accounted for the separation...
I've never heard of such a force description in all my school years.
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I drove the -200 for a number of years and it was routine to have a reverser open on the 6th month checks. It took a lot of rudder until you got the engine shut down, a bit more so than just an engine failure, of course.
A few things added to the drill. 1) if you had your hands in the wrong place when the reverser opened, you got a good shot as the throttle slammed to idle. Not fun. 2) the event was usually introduced shortly after getting airborne and V2 engine problems require much better footwork on the rudder than a simple V1 failure. 3) after shutting down the engine it was pretty much just another single engine approach except slightly higher power settings due to the drag.
At 'my house' a friend of mine had an engine separate coming out of PHL just after takeoff. No problem. Again, just another single engine approach.
The little -200 would trim up very nicely for such an approach and the only problem was not trying to hold the airplane off for a smooth touchdown as with flaps 15, it would float forever.
FWIW, the 727 also tossed a few engines. The bolts holding the engine on the pylon are not that thick and are designed to fail with a 'catastrophic seizure' as some others have noted. Better to have the engine leave the airplane than have the gyroscopic forces tear up fuselage or wing (in the 737s case).
A few things added to the drill. 1) if you had your hands in the wrong place when the reverser opened, you got a good shot as the throttle slammed to idle. Not fun. 2) the event was usually introduced shortly after getting airborne and V2 engine problems require much better footwork on the rudder than a simple V1 failure. 3) after shutting down the engine it was pretty much just another single engine approach except slightly higher power settings due to the drag.
At 'my house' a friend of mine had an engine separate coming out of PHL just after takeoff. No problem. Again, just another single engine approach.
The little -200 would trim up very nicely for such an approach and the only problem was not trying to hold the airplane off for a smooth touchdown as with flaps 15, it would float forever.
FWIW, the 727 also tossed a few engines. The bolts holding the engine on the pylon are not that thick and are designed to fail with a 'catastrophic seizure' as some others have noted. Better to have the engine leave the airplane than have the gyroscopic forces tear up fuselage or wing (in the 737s case).
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Originally Posted by IGh
The best summary of the varying design concepts is found in the early 1990's -- some of the reporting may be available on the "web". The _Seattle Times_ had some excellent reviews of the competing design concepts -- Boeing's vs Airbus'.
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Flight CE 723 was discontinued following an incident yesterday soon after take off from Cape Town International Airport.
What a joke - the flight was discontinued - a nice way of saying that their was no way that the crew could continue to Johannesburg, even though I wanted them to!!!
Bricknell says this is the first major incident that the airline has experienced since taking to the skies 12 years ago.
I seem to remember a BAC 111 losing an engine from JNB to GRJ, and the crew electing to continue to GRJ on one engine!!! No press to give Vernie a hard time then and he got away with it!! A picture of a missing toilet servicing cap does not make for good reading - not enough blood and guts, oops, sorry, just blood!!
He (Vernon) says the airline industry is the most regulated sector in the world in terms of safety, training and aircraft maintenance.
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I'd be interested in the opinions of the professionals here about an article from Independent Online in SA. It seems well written without the normal sensationalisms that are often (rightly) castigated here.
http://www.int.iol.co.za/index.php?s...3801406C807260
http://www.int.iol.co.za/index.php?s...3801406C807260
This bit is great:
Right.
But that's not what happened, according to the source who examined the damaged wing on Thursday.
"I'm not a structural engineer, but I examined the damaged wing up close and it was very clear that one of the pylon's struts - about the thickness of your arm - had sheared clean through, as if cleft with an axe," said the source.
"It appears as if once the strut had sheared, it tore the right-hand side bolt clean out of the wing, then the whole engine detached itself.
"The strut that sheared was the one closest to the fuselage.
"I don't know if there was a latent crack there or something (else) that had not been picked up during inspection."
"I'm not a structural engineer, but I examined the damaged wing up close and it was very clear that one of the pylon's struts - about the thickness of your arm - had sheared clean through, as if cleft with an axe," said the source.
"It appears as if once the strut had sheared, it tore the right-hand side bolt clean out of the wing, then the whole engine detached itself.
"The strut that sheared was the one closest to the fuselage.
"I don't know if there was a latent crack there or something (else) that had not been picked up during inspection."
I'd be interested in the opinions of the professionals here about an article from Independent Online in SA. It seems well written without the normal sensationalisms that are often (rightly) castigated here.
http://www.int.iol.co.za/index.php?s...3801406C807260
http://www.int.iol.co.za/index.php?s...3801406C807260
From the clear pictures I have seen of the engine fan there is no significant damage.
Engineers do not know what loads will break the mount, they only know that at a prescribed load level it won't break (there is a difference)
I'm not a fan of concentrating on the obvious damage to a dual mount link and ascribing it as primary with a wave of the typewriter as fatigue. It is entirely possible it is secondary to the other side as primary.
So what did happen on the other side??
Yes the design is relatively failsafe as it protects the wing box while allowing the engine to fall away resulting in less thrust, less drag and a redundant hydraulic system left to fly the aircraft
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Here's a link to an article that IGh mentioned:
http://archives.seattletimes.nwsourc...&date=19930109
http://archives.seattletimes.nwsourc...&date=19930109
http://archives.seattletimes.nwsourc...&date=19930109
"We have no fuse pins," said a high-ranking Airbus engineer. "In other words, we have designed it so that (the engine and strut) will stay attached to the wings in all circumstances."
"We have no fuse pins," said a high-ranking Airbus engineer. "In other words, we have designed it so that (the engine and strut) will stay attached to the wings in all circumstances."
Airbus only knows what has happened so far not that they can stay attached in all circumstances including in the air due to any engine failure.
How well did they survive in Quito A340? How well did they stay attached on The A300 in AA587?
How well will they survive with about 5 fan blades missing?
The FAA spokesman said it correctly both Boeing and Airbus mounts are "safe enough" else they wouldn't both be flying today.
It's best not to claim "not me" in the midst of public agony about the other guy.
I'll admit that the degree of redundant load paths could be different, but in the case of the B747 experience, cited in the article, indeterminate multiple load paths are not desireable or easy to fix when you can't simply figure out what will break it in the first place.
So what makes all this public discussion to get Byron Acohido and his typewriter energized? Does he really have an end point? Does he feel that the recent B737 was another disaster in the making like his rudder teatise?
Last edited by lomapaseo; 12th Nov 2007 at 20:40.
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More pics of the aircraft and engine.
It's a Norwegian forum...so just scroll down to find the pics.
http://www.flightsim.no/ubbthreads/u...169#Post373169
It's a Norwegian forum...so just scroll down to find the pics.
http://www.flightsim.no/ubbthreads/u...169#Post373169
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According to the African forum the SACAA have issued an AD grounding all 737-200's in South Africa, pending examination.I believe that NW operate 12 of them.
That's going to hurt.
That's going to hurt.
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Sr. Lomapaseo,
I do not think that the article is misleading at all. There are just 2 different design concepts for taking care of the longitudinal and transversal loads during normal operation:
Boeing accepts that an engine might leave the wing with no redundancy if an attachment bolt fails. They claim that they designed it in a way that it does not damage the fuel tanks inside the wing during separation. The pictures on the Norwegian website show that the concept worked. The flip side is that they rely on competent maintenance teams to check in short intervals regularly the bolts and replace them with (costly) genuine OEM parts, if they detect any flaws.
Airbus on the other hand makes it under all circumstances a permanent attachment by designing redundancy in.
Both concepts are approved by the authorities on both sides of the pond, so there is not a good and a bad one, also proven by millions of incident free flights.
Your hint at the Iberia Quito incident is misleading indeed. It prooves that the Airbus concept can withstand also design loads outside of the operating enveloppe. Please note that both engines are still on wing, although at some strange unpreferred angles.
Comparing both design concepts I personally do not want to leave especially Quito in a 777 dumping one engine on the runway.
Frank
I do not think that the article is misleading at all. There are just 2 different design concepts for taking care of the longitudinal and transversal loads during normal operation:
Boeing accepts that an engine might leave the wing with no redundancy if an attachment bolt fails. They claim that they designed it in a way that it does not damage the fuel tanks inside the wing during separation. The pictures on the Norwegian website show that the concept worked. The flip side is that they rely on competent maintenance teams to check in short intervals regularly the bolts and replace them with (costly) genuine OEM parts, if they detect any flaws.
Airbus on the other hand makes it under all circumstances a permanent attachment by designing redundancy in.
Both concepts are approved by the authorities on both sides of the pond, so there is not a good and a bad one, also proven by millions of incident free flights.
Your hint at the Iberia Quito incident is misleading indeed. It prooves that the Airbus concept can withstand also design loads outside of the operating enveloppe. Please note that both engines are still on wing, although at some strange unpreferred angles.
Comparing both design concepts I personally do not want to leave especially Quito in a 777 dumping one engine on the runway.
Frank
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Tech log entry
Would an entry of "right engine missing" be appropriate for maintenance in this case or something more elaborate like "suspect bolts and nuts not adhering to aircraft skin anymore"?
Sr. Lomapaseo,
I do not think that the article is misleading at all. There are just 2 different design concepts for taking care of the longitudinal and transversal loads during normal operation:
Boeing accepts that an engine might leave the wing with no redundancy if an attachment bolt fails. They claim that they designed it in a way that it does not damage the fuel tanks inside the wing during separation. The pictures on the Norwegian website show that the concept worked. The flip side is that they rely on competent maintenance teams to check in short intervals regularly the bolts and replace them with (costly) genuine OEM parts, if they detect any flaws.
Airbus on the other hand makes it under all circumstances a permanent attachment by designing redundancy in.
Both concepts are approved by the authorities on both sides of the pond, so there is not a good and a bad one, also proven by millions of incident free flights.
Your hint at the Iberia Quito incident is misleading indeed. It prooves that the Airbus concept can withstand also design loads outside of the operating enveloppe. Please note that both engines are still on wing, although at some strange unpreferred angles.
Comparing both design concepts I personally do not want to leave especially Quito in a 777 dumping one engine on the runway.
Frank
I do not think that the article is misleading at all. There are just 2 different design concepts for taking care of the longitudinal and transversal loads during normal operation:
Boeing accepts that an engine might leave the wing with no redundancy if an attachment bolt fails. They claim that they designed it in a way that it does not damage the fuel tanks inside the wing during separation. The pictures on the Norwegian website show that the concept worked. The flip side is that they rely on competent maintenance teams to check in short intervals regularly the bolts and replace them with (costly) genuine OEM parts, if they detect any flaws.
Airbus on the other hand makes it under all circumstances a permanent attachment by designing redundancy in.
Both concepts are approved by the authorities on both sides of the pond, so there is not a good and a bad one, also proven by millions of incident free flights.
Your hint at the Iberia Quito incident is misleading indeed. It prooves that the Airbus concept can withstand also design loads outside of the operating enveloppe. Please note that both engines are still on wing, although at some strange unpreferred angles.
Comparing both design concepts I personally do not want to leave especially Quito in a 777 dumping one engine on the runway.
Frank
My major point had to do with this side of the discussion
Airbus on the other hand makes it under all circumstances a permanent attachment by designing redundancy in.
And I am not a supporter of redundancy in an engine mount when you break a wing box and still have retained the engine in an abnormality.
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Tech Log Entry
Well the Engineers hate Pilots making the diagnosis so you'd have to just give the symptoms:
"Moderate right yaw observed shortly after takeoff. On subsequent walkaround, F/O noted more headroom than usual whilst checking right wing underside"
Great effort guys.
"Moderate right yaw observed shortly after takeoff. On subsequent walkaround, F/O noted more headroom than usual whilst checking right wing underside"
Great effort guys.