Air Transat loses A310 rudder inflight
The Reverend
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I'm not familiar with the test schedule of aircraft composites but would imagine that extensive immersion tests would have been carried out prior to certification and release of the materials.
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Ignition Override,
That type of thinking is not out of bounds, just come up with a sound justification.
I cannot speak of the 7E7/787 program, on the 7J7/777 project the most critical environment expected in airline service in areas away from local heat sources the thermal analysis predicted a maximum inflight temperature of 71°C and a minimum temperature of -54°C. The effect of moisture on the material systems applied in the empenage (the 777 has a carbon-fiber-reinforced plastic (CFRP) horizontal and vertical stabilisers, elevators, and rudder) and determined that it is highly unlikely that a moisture content of 1.1 % by weight will be exceeded in service.
FAR and JAR 25.571 and FAA Advisory Circular 20-107A, composite aircraft structure, and the JAA, ACJ 25.603, composite aircraft structure (acceptable means of compliance) describe two primary damage tolerance requirements... damage growth characterisation and residual strength capability. As in the case of static strength damage tolerance certification is based on analysis supported by tests at element, subcomponent, and component levels.
Considering the applied strains, a "no-growth" approach was selected for the 777 empenage similar to that used for the 737 graphite-epoxy horizontal stabilizer. This philosophy states that any damage that is visually undetectable is not critical. Structures with this type of damage must be capable of carrying ultimate load for the operational life of the airplane. For the tests saw cuts were made to the front and rear spar to demonstrate the capability to sustain continued safe-flight loads as per FAR/JAR 25.571e.
No growth behavior was exhibited in numerous subcomponent tests and two full scale cyclic load tests, the 7J7 horizontal stabiliser and the preproduction 777 horizontal stabiliser. I During test theyh were deliberatly damaged so that visible damage was inflicted on the test article that underwent repeated loading (representive of flight loads), and underwent inspections of the damaged sites for growth during the test sequence.
The end result of the tests it was found that manufacturing anomalies allowed per the process specifications will not grow for the equivalent of more than two design service lives. Visible damage due to foreign-object impact will not grow for the duration of two inspection intervals. The structure can sustain specified residual strength loads with damage that can reasonably be expected in service. The structure can sustain specified static loads ("continued safe flight loads") after incurring in-flight discrete-source damage.
Further information on the certification of composites and material and process specifications can be found in the FAR/JARs
25.603 Control of materials
25.605 Fabrication methods
25.613 Material strength properties
25.615 Design properties
25.619 Special factors
25.305 Strength and deformation
25.307 Proof of structure
25.571 Fatigue evaluation, residual strength, discrete source damage
25.581 Lightning protection
25.609 Protection of structure
The technology employed by Airbus when designing the A310 is similar to that used today. There are two main difference in the use of composites today, the resins available, and the software.
The resins now available are toughened more and generally less dense, meaning that service life for parts increases and it is lighter, for example the 777 rudder design life is 40000 flights of 1,5 hours duration, 25000 flights of 3 hours duration, or 10000 flights of 9 hours duration. Older aircraft with earlier resins have lower design lives and heavier parts, meaning cost more to maintain, and less payload.
Improved software allows for improved geometry, improved automatic manufacturing, optimized lay-up of carbon-fiber-reinforced plastic direction, and improved analysis like of woven composite materials. Meaning stronger and lighter parts.
From my understanding the 787 can be ordered with either stick of yoke. Why anyone would want to go 14 hours with something between their legs is beyond me. Worked for the F16.
Advanced diagnostic techniques for composites are available and are used at the manufacturing quality assurance stage. For example I remember seeing some color ultrasonic scans of a part that was hand manufactured consisting of several layers of carbon fiber material layered in different geometries. The part was rejected as the scan clearly showed the outline of a human hand, apparently of the technicians forgot to wear a glove when laying up one sheet of material and the fat from their hand prevented the two associated layers to bond showing up as a void.
The AD that has been raised is to establish if there is any statistical basis that the structural integrity is inadequate fleet wide, it a precautionary AD and a prudent course of action as it will either establish or diminish the integrity of the part with higher and lower cycles and hours than both AA587 and TS961.The aim of this Emergency Airworthiness Directive (EAD) is to check the structural integrity of the rudder and its attachment by means of a one time inspection (general visual inspection, detailed visual inspection and tap test inspection), as a precautionary action.
That type of thinking is not out of bounds, just come up with a sound justification.
I cannot speak of the 7E7/787 program, on the 7J7/777 project the most critical environment expected in airline service in areas away from local heat sources the thermal analysis predicted a maximum inflight temperature of 71°C and a minimum temperature of -54°C. The effect of moisture on the material systems applied in the empenage (the 777 has a carbon-fiber-reinforced plastic (CFRP) horizontal and vertical stabilisers, elevators, and rudder) and determined that it is highly unlikely that a moisture content of 1.1 % by weight will be exceeded in service.
FAR and JAR 25.571 and FAA Advisory Circular 20-107A, composite aircraft structure, and the JAA, ACJ 25.603, composite aircraft structure (acceptable means of compliance) describe two primary damage tolerance requirements... damage growth characterisation and residual strength capability. As in the case of static strength damage tolerance certification is based on analysis supported by tests at element, subcomponent, and component levels.
Considering the applied strains, a "no-growth" approach was selected for the 777 empenage similar to that used for the 737 graphite-epoxy horizontal stabilizer. This philosophy states that any damage that is visually undetectable is not critical. Structures with this type of damage must be capable of carrying ultimate load for the operational life of the airplane. For the tests saw cuts were made to the front and rear spar to demonstrate the capability to sustain continued safe-flight loads as per FAR/JAR 25.571e.
No growth behavior was exhibited in numerous subcomponent tests and two full scale cyclic load tests, the 7J7 horizontal stabiliser and the preproduction 777 horizontal stabiliser. I During test theyh were deliberatly damaged so that visible damage was inflicted on the test article that underwent repeated loading (representive of flight loads), and underwent inspections of the damaged sites for growth during the test sequence.
The end result of the tests it was found that manufacturing anomalies allowed per the process specifications will not grow for the equivalent of more than two design service lives. Visible damage due to foreign-object impact will not grow for the duration of two inspection intervals. The structure can sustain specified residual strength loads with damage that can reasonably be expected in service. The structure can sustain specified static loads ("continued safe flight loads") after incurring in-flight discrete-source damage.
Further information on the certification of composites and material and process specifications can be found in the FAR/JARs
25.603 Control of materials
25.605 Fabrication methods
25.613 Material strength properties
25.615 Design properties
25.619 Special factors
25.305 Strength and deformation
25.307 Proof of structure
25.571 Fatigue evaluation, residual strength, discrete source damage
25.581 Lightning protection
25.609 Protection of structure
The technology employed by Airbus when designing the A310 is similar to that used today. There are two main difference in the use of composites today, the resins available, and the software.
The resins now available are toughened more and generally less dense, meaning that service life for parts increases and it is lighter, for example the 777 rudder design life is 40000 flights of 1,5 hours duration, 25000 flights of 3 hours duration, or 10000 flights of 9 hours duration. Older aircraft with earlier resins have lower design lives and heavier parts, meaning cost more to maintain, and less payload.
Improved software allows for improved geometry, improved automatic manufacturing, optimized lay-up of carbon-fiber-reinforced plastic direction, and improved analysis like of woven composite materials. Meaning stronger and lighter parts.
From my understanding the 787 can be ordered with either stick of yoke. Why anyone would want to go 14 hours with something between their legs is beyond me. Worked for the F16.
Advanced diagnostic techniques for composites are available and are used at the manufacturing quality assurance stage. For example I remember seeing some color ultrasonic scans of a part that was hand manufactured consisting of several layers of carbon fiber material layered in different geometries. The part was rejected as the scan clearly showed the outline of a human hand, apparently of the technicians forgot to wear a glove when laying up one sheet of material and the fat from their hand prevented the two associated layers to bond showing up as a void.
The AD that has been raised is to establish if there is any statistical basis that the structural integrity is inadequate fleet wide, it a precautionary AD and a prudent course of action as it will either establish or diminish the integrity of the part with higher and lower cycles and hours than both AA587 and TS961.The aim of this Emergency Airworthiness Directive (EAD) is to check the structural integrity of the rudder and its attachment by means of a one time inspection (general visual inspection, detailed visual inspection and tap test inspection), as a precautionary action.
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..it is highly unlikely that a moisture content of 1.1 % by weight will be exceeded in service.
For that much water to get into a composite part aren't we talking about water getting into voids? I mean, I can't see that much water being in the resin when the part is being made!
If we are talking about water penetration into voids or hollow parts why would there be such a precise expectation as to how much that would be limited to?
Any experts out there know where this figure comes from?
DOVE
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ZEKE:
Quote:
... for example the 777 rudder design life is 40000 flights of 1,5 hours duration, 25000 flights of 3 hours duration, or 10000 flights of 9 hours duration. ...
Will you please be so kind to tell me:
1) What is, more or less, the stress on the root of the rudder of a 747-400 flying with one internal engine, exactly number 2, inoperative, the others running at MCL, and the trim displaced to compensate the yaw?
2) And the stress on the fuselage for the same conditions?
3) And how many flights of 12 hours duration in the above conditions are needed to fulfil the 747-400 rudder design life?
I admire your knowledge and I'm anxious to have your precious answer.
Regards
DOVE
Quote:
... for example the 777 rudder design life is 40000 flights of 1,5 hours duration, 25000 flights of 3 hours duration, or 10000 flights of 9 hours duration. ...
Will you please be so kind to tell me:
1) What is, more or less, the stress on the root of the rudder of a 747-400 flying with one internal engine, exactly number 2, inoperative, the others running at MCL, and the trim displaced to compensate the yaw?
2) And the stress on the fuselage for the same conditions?
3) And how many flights of 12 hours duration in the above conditions are needed to fulfil the 747-400 rudder design life?
I admire your knowledge and I'm anxious to have your precious answer.
Regards
DOVE
UPDATE
http://www.newsday.com/news/local/lo...news-headlines
"American acknowledged Friday that its inspections of two Airbus 300-600s found "minor delamination""..............
Like, just a little pregnant?
Surely, there's someone out there with an ear to the ground....any rumblings?
http://www.newsday.com/news/local/lo...news-headlines
"American acknowledged Friday that its inspections of two Airbus 300-600s found "minor delamination""..............
Like, just a little pregnant?
Surely, there's someone out there with an ear to the ground....any rumblings?
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Talking about "the composite material that made up the rudder and tail of the two planes" is like talking about the metal material that makes up the kitchen wrap foil and the wings.
Although fin and rudder are made from carbon fibre epoxy composites, that is all that is common.
The rudder is made of sandwich material with thin (less than 1 mm) carbon fibre skins on nomex/phenol honeycomb, while the fin is made of integrally rib and stringer stiffened thick (up to more than 10 mm) monolitic carbon fibre shells.
IŽm not 100% shure, but I also think the rudder is made from bidirectional woven fabric prepregs while the fin is made from unidirectional fibre tape prepregs.
Finding "minor delaminations" in composites is like finding dents, loose rivets, small cracks or minor corrosion on metals. It weakens, but not below the tested strength level.
ItŽs a long way from pregnancy to maternity
Although fin and rudder are made from carbon fibre epoxy composites, that is all that is common.
The rudder is made of sandwich material with thin (less than 1 mm) carbon fibre skins on nomex/phenol honeycomb, while the fin is made of integrally rib and stringer stiffened thick (up to more than 10 mm) monolitic carbon fibre shells.
IŽm not 100% shure, but I also think the rudder is made from bidirectional woven fabric prepregs while the fin is made from unidirectional fibre tape prepregs.
Finding "minor delaminations" in composites is like finding dents, loose rivets, small cracks or minor corrosion on metals. It weakens, but not below the tested strength level.
ItŽs a long way from pregnancy to maternity
"....probably not an operational problem...Investigators are also curious about a small square hole and several smaller holes found in the tail section...Maintenance records showed...only some minor work on composite material bonding."
then, the rudder falls off?
http://www.iht.com/articles/2005/03/31/news/rudder.html
(2 pages here)
then, the rudder falls off?
http://www.iht.com/articles/2005/03/31/news/rudder.html
(2 pages here)
The silence on this topic is deafening!!!!!!!!
There has to be someone out there with a reliable info source for something....ANYTHING.....maybe?????????
I'd even stand for a 9 in a 1-10 scale of "reliable" sources!
-how 'bout an 8?
There has to be someone out there with a reliable info source for something....ANYTHING.....maybe?????????
I'd even stand for a 9 in a 1-10 scale of "reliable" sources!
-how 'bout an 8?
Eight Gun Fighter
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(grounded for months waiting for a new tail)
Rebel PPRuNer
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rollingthunder
I imagine given the differences in production rates for 310 over 320 the chances of a fin being "to spare" is rather higher for a 320! God that Beluga's ugly though...
I imagine given the differences in production rates for 310 over 320 the chances of a fin being "to spare" is rather higher for a 320! God that Beluga's ugly though...
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When you made it for the 320 within a few hours this does not mean that everyone makes it so well in that time
I assume that rudder was from XLW where a few A321s destinated for US Airways have not been completed so there was a rudder avaible just by call
Sticking back to the topic, maybe I didn't see it, how about the investigation.
Is it possible that the acft is stored without tail for further examination of the fuselage, tail-section...?
Regards
I assume that rudder was from XLW where a few A321s destinated for US Airways have not been completed so there was a rudder avaible just by call
Sticking back to the topic, maybe I didn't see it, how about the investigation.
Is it possible that the acft is stored without tail for further examination of the fuselage, tail-section...?
Regards
Union Goon
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At AA, In the ensuing aftermath of 587 they found ANOTHER vertical stab that needed to be replace. They were waiting over a year for it... They were pretty sure that damage had been in the stab for several heavy maintance checks and undiscovered by the Airbus procedures in place (and still recommended) at the time.
There was a lot of damage around the lug, that turned out to be undectable untill the entire stab was removed from the airplane, somthing that Airbus had strenously objected to American doing.
Cheers
Wino
There was a lot of damage around the lug, that turned out to be undectable untill the entire stab was removed from the airplane, somthing that Airbus had strenously objected to American doing.
Cheers
Wino
Too mean to buy a long personal title
Wino: At AA, In the ensuing aftermath of 587 they found ANOTHER vertical stab that needed to be replace. They were waiting over a year for it... They were pretty sure that damage had been in the stab for several heavy maintance checks and undiscovered by the Airbus procedures in place (and still recommended) at the time.
Union Goon
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Yeah, I think so.
It MIGHT have been the one with the autopilot problem however. There was a case where the autopilot didn't declutch from the rudder axis when it disconnected, causing continous violoent and rapid swings back and forth for the balance of the flight. Was a very exciting landing (also in Miami as I recall.)
That lead to the warning to try the opposit side autopilot should that sort of thing happen in the future....
Cheers
Wino
It MIGHT have been the one with the autopilot problem however. There was a case where the autopilot didn't declutch from the rudder axis when it disconnected, causing continous violoent and rapid swings back and forth for the balance of the flight. Was a very exciting landing (also in Miami as I recall.)
That lead to the warning to try the opposit side autopilot should that sort of thing happen in the future....
Cheers
Wino
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hobie
Composite structure can be examined using a number of non destructive inspection methods which provide much more reliable and less error prone results than 'tap testing' surface areas the size of small countries with a coin. Even if the engineer inspects with total discipline he/she will only find damage near the surface.
A better method is X-ray, a technique already widely used for matallic structures. Unfortunately there are few of these techniques available for composite as they tend to be driven by 'in service' experience.
Hopefully this incident will drive the industry to find sound and reliable solutions to a long awaited request from maintenance engineers to be equipped with something more elaborate than percussive interpretation.
Composite structure can be examined using a number of non destructive inspection methods which provide much more reliable and less error prone results than 'tap testing' surface areas the size of small countries with a coin. Even if the engineer inspects with total discipline he/she will only find damage near the surface.
A better method is X-ray, a technique already widely used for matallic structures. Unfortunately there are few of these techniques available for composite as they tend to be driven by 'in service' experience.
Hopefully this incident will drive the industry to find sound and reliable solutions to a long awaited request from maintenance engineers to be equipped with something more elaborate than percussive interpretation.
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darkbarly
x-ray is the least favorable method to detect damage in composite structure. It is OK to find water ingress in honeycomb sandwich, but useless to find delamination in more or less flat panels. You have to use x-ray in the same plane as the delamination to see it, but normally you are just able to apply x-ray perpendicular to the surface. As long as no contamination has filled the delaminated area, you will see nothing. If you are looking for delaminations close to metallic bushings, they will hide the damage due to the high x-ray absorption of metals compared to composite.
Ultrasonic is most effective for inspecting monolithic composite structure for delaminations.
To give a simple statement, you could say : If the damage is large enough to be harmful, it can be found by visual inspection and tap testing. If you need ultrasonic or x-ray to detect it, it is most probably not dangerous at the moment.
x-ray is the least favorable method to detect damage in composite structure. It is OK to find water ingress in honeycomb sandwich, but useless to find delamination in more or less flat panels. You have to use x-ray in the same plane as the delamination to see it, but normally you are just able to apply x-ray perpendicular to the surface. As long as no contamination has filled the delaminated area, you will see nothing. If you are looking for delaminations close to metallic bushings, they will hide the damage due to the high x-ray absorption of metals compared to composite.
Ultrasonic is most effective for inspecting monolithic composite structure for delaminations.
To give a simple statement, you could say : If the damage is large enough to be harmful, it can be found by visual inspection and tap testing. If you need ultrasonic or x-ray to detect it, it is most probably not dangerous at the moment.