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New problems with A300 rudders

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New problems with A300 rudders

Old 28th Mar 2006, 14:20
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Gautteng,

4 or 5 years ago boeing did just that with a a very high cycle 747. They used it to verify their ageing aircraft program. Infact parts of the aircraft can be seen in the boeing factory tour. Atleast they could a few years ago.l


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Wino
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Old 28th Mar 2006, 17:57
  #22 (permalink)  
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Learn from the Marine experience - no thanks...

There is not much that the marine industry can offer regarding composite knowledge. Sure, the marine sector makes good R&D contributions regarding materials and manufacturing processes but as a previous poster mentioned, this is not the challenge.

Forget anything that is done for whacky one-off racing yachts; when you are considering a product that will be used with high frequency for a long service duration, you need to look at the commercial marine sector for such products - and there is very little there that would advance the aircraft industry.

For a composite (FRP) ship or boat, the design gets certification to do a certain task for 25 years and thus remain insurable within acceptable statistical limits. The design factors used in the stress analysis are in a different league to the aircraft industry (design it then double the size in case someone drops a hammer on it). Product testing is governed by the intended loading conditions (i.e. combination of speed and sea state) and as a result almost impossible to accurately predict.

In service, the marine product gets unpredictably bashed between two fluids, one of a relatively very high density (water) and one of a very low density (air). You simply cannot take an FRP ship or boat and talk about 'loading cycles' to the structural engineers in the same way you can with a plane. The stress cycle of a boat going between two ports is not so predictable in the same way as an aircraft going between two airports.

The marine FRP inspections are relatively crude and mainly manual. Access to do this, when compared to an aircraft, is simple. Analysis result is either it (the composite) has delaminated or it has not, whether due to moisture or trauma. No one in the marine industry can tell you that this bit of composite can survive X number more loading cycles before catastrophic failure, let alone define the macro loading cycle with sufficient accuracy.

Given all the above, the marine engineering community is hardly well positioned to deliver anything of real significance.
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Old 28th Mar 2006, 20:37
  #23 (permalink)  
 
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Airbus denies A300 tail issues and ignores new inspection recommendations.

From the Transportation Safety Board of Canada:

"Airbus inspections of some rudders on its planes aren't frequent enough to identify problems with the aircraft"

The agency recommended more inspections after probing an incident involving an Airbus A310-300 flown by Air Transat, which lost its rudder March 6, 2005, after departing from Cuba.

The investigation "suggests that the current inspection program for Airbus composite rudders might not ensure the timely detection of defects," the Transportation Safety Board said in a statement."
This advisory comes shortly after the NTSB's urgent advisory on Friday to the FAA for an improved inspection regime for about 400 Airbus aircraft including a check for skydrol-contaminated structures.

The "urgent" recommendation by the NTSB stemmed from a Nov. 27, 2005, incident involving a rudder on an Airbus A300-600 operated by FedEx. The rudder was damaged during routine maintenance and sent to the manufacturing facility for an assessment of damage.

During the inspection, a "substantial area" of separation was found between the inner skin of the composite rudder surface and its honeycomb core, along with hydraulic fluid, which can lead to progressive separation and compromise the rudder strength, the agency said.

"Tests on the damaged rudder also revealed that disbonding damage could spread during flight," the NTSB said in a statement issued Friday.
The NTSB recommended that the FAA establish a "repetitive inspection interval" on Airbus planes without modified rudders "well below" the current standard of every 2,500 flights.
Meanwhile, Airbus denies any problems with their recommended inspection interval for these aircraft and says they will not change the maintenance schedule:

"We are still confident in our inspection schedule that we recommended to operators earlier this month," Airbus spokeswoman Mary Anne Greczyn said Monday.

"While the NTSB is recommending an expedited inspection of the relevant rudders, Airbus remains confident in the operating safety of these aircraft and our original recommendations for inspection," Greczyn said.
Later last year after the un-commanded rudder excursion was demonstrated by FedEx maintenance on one of their A300s, Airbus prudently recommended further inspections of the laminate without regulatory prodding.

I wonder why they are resisting now ?

And when will we be seeing enhanced preventative maintenance procedures on aircraft like the 777 and many others ?
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Old 28th Mar 2006, 20:55
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This sounds similar to the degredation of the foam core of certain types of propeller blades, when engine oil from the prop hub seeped into the area between the metal spar and the core...caused the loss of at least one Brasilia and a couple of the ATR's in our fleet were found to have weakened blades as well.

I guess petroleum products and glassfibre/composites really don't mix well after curing!

TT
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Old 28th Mar 2006, 20:59
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Given all the above, the marine engineering community is hardly well positioned to deliver anything of real significance (about strength of composites in aircraft).
Points well made, Tallsandwich.

By way of footnote, I would add:

a) With most nautical craft, excepting a few military vessels, it is relatively difficult and exceptional to be able to push them - deliberately or accidentally - up to and beyond the engineered design strength limits.

With aircraft, however, driving the airframe, engines, and systems up to and beyond design limits is possible during each and every operational use of the machine, as well as sometimes during ground handling and maintenance.

b) An important consideration relating to questions about service life of composite components vs traditional metal, wood, and other mfg techniques is that composites are typically "created" in place, with strength and durability reliant on invisible qualities derived from that creation. Like barrels of wine, each unit has some hard-to-quantify variability when made that creates unknown implications for its ultimate competence in service.

Lacking informative means to assess the future durability of composite materials incorporated in individual assembled units and units in the field, we seem to be operating in an uncomfortably dark zone of adverse possibilities. While this standard may be acceptable in military use, where composites have provided distinguished service, a much more conservative approach seems warranted in Civil Aviation, for use by the general public.
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Old 29th Mar 2006, 06:52
  #26 (permalink)  
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I guess petroleum products and glassfibre/composites really don't mix well after curing!
TT - These problems can be easily overcome if they are forseen - take a look at this FRP ship - with diesel in it's FRP tanks.

Sure no one expects a propeller to be immersed in a hyrdocardon product as they do with a bulk fuel tank, but as a propeller blade is situated right next to a fuel tank and an engine....it could be argued that this contamination should have been forseen.
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Old 30th Mar 2006, 04:47
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Danger

VA Pilot 2004: You beat me to the info, at least on Pprune.

A US newspaper today published a long article on the topic and said that "FEDEX is Airbus' largest customer in the world".
What is revealing to me is that the Air Transat aircraft lost 95
% of the rudder (!) and this happened ONE YEAR AGO this month.
Is the FAA still not yet requiring US companies to make this inspection?

How much more important is the cost factor in the FAA's cost versus benefit equation?
Let's not forget the FAA's total disregard of the (documented with foreign airlines) ATR-42's unpredictable flight characteristics in certain icing conditions (aileron "snatch"), until...a smashed plane with smashed bodies in Roselawn, Indiana.

How different are the composite materials in newer Airbus A-319/320 and Boeing 787s? The problem is apparently not caused by hydraulic fluid, by itself.

Last edited by Ignition Override; 31st Mar 2006 at 03:42.
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Old 30th Mar 2006, 05:40
  #28 (permalink)  
 
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Link to NTSB urgent release regarding this:NTSB Airbus A300 Rudder

Ignition Override, you know, along with FedEx and American Airlines (the only US carriers operating this aircraft), shouldn't the remaining A300/A310 fleet be examined ?

This is not a minor issue since the A300 series has only one rudder surface. I strongly feel that Airbus needs to issue another AOT right away. The FAA is also a bit of an enigma, isn't it ?

I have an idea that the composites used in the A320 and 787 haven't changed that much since the A300 was built. Boeing claims to be using a more sophisticated monitoring system on the 787, but what about the triple 7 ?

Let us all hope that some intrepid maintenance engineers are already looking carefully at the aging composites in our collective fleets.
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Old 1st Apr 2006, 21:48
  #29 (permalink)  
 
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The AD issued 30/03/06:
http://www.airweb.faa.gov/Regulatory...D?OpenDocument
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