Airbus rudder AD

[Morgans]

Did anyone catch this on avflash?

Quote: it now appears airlines operating A300 and A310 aircraft will be
compelled to conduct thorough inspections of the planes' composite rudders.
France's civil aviation regulator has issued an Emergency Airworthiness
Directive calling for the one-time visual and tap-test inspection to be
completed within 550 hours or before June 18. it now appears airlines
operating A300 and A310 aircraft will be compelled to conduct thorough
inspections of the planes' composite rudders. France's civil aviation
regulator has issued an Emergency Airworthiness Directive calling for the
one-time visual and tap-test inspection to be completed within 550 hours or
before June 18. End quote.

A tap test? Is this is the best they can do to find possible flaws on
multimillion dollar aircraft, carrying thousands of people around? Surely
there is a better way!
--
Jim in NC

[Colin W Kingsbury]

"Morgans" > wrote in message
...
> Did anyone catch this on avflash?
>
<SNIP>
>
> A tap test? Is this is the best they can do to find possible flaws on
> multimillion dollar aircraft, carrying thousands of people around? Surely
> there is a better way!

I have a couple of feelings on the issue. First, the A300/310 is hardly new,
with plenty of airframes flying for 10-20 years with all kinds of operators,
and this is the first we see of it. So my initial instinct is to think that
there is something beyond design at work here. I'm not a materials engineer
but it seems that the "composites are new and we don't fully understand
them" argument is growing a little long in the tooth. There are Long-EZs
that have been flying for quite some time and those were amateur-built. But
what the heck do I know?

What I do know is that there is a little something called the A380 in which
France has quite a vested interest that is full of composite parts and they
don't want to panic the sheep, er, public. And given that the 787 is also a
plastic airplane, for once Boeing wouldn't want to see any mud flung either.

-cwk.

[Matt Whiting]

Colin W Kingsbury wrote:

> "Morgans" > wrote in message
> ...
>
>>Did anyone catch this on avflash?
>>
>
> <SNIP>
>
>>A tap test? Is this is the best they can do to find possible flaws on
>>multimillion dollar aircraft, carrying thousands of people around? Surely
>>there is a better way!
>
>
> I have a couple of feelings on the issue. First, the A300/310 is hardly new,
> with plenty of airframes flying for 10-20 years with all kinds of operators,
> and this is the first we see of it. So my initial instinct is to think that
> there is something beyond design at work here. I'm not a materials engineer
> but it seems that the "composites are new and we don't fully understand
> them" argument is growing a little long in the tooth. There are Long-EZs
> that have been flying for quite some time and those were amateur-built. But
> what the heck do I know?

True, but we don't have 50 years of experience with composites in
service. Who knows what their deterioration/age related failure modes
may be? Remember, it took a couple of fatal accidents to begin to
understand fatigue and corrosion issues in aluminum...


Matt

[Helen Woods]

And who was it insulting me earlier on this list for not wanting to fly
plastic airplanes???

[Morgans]

"Matt Whiting" > wrote

>
> True, but we don't have 50 years of experience with composites in
> service. Who knows what their deterioration/age related failure modes
> may be? Remember, it took a couple of fatal accidents to begin to
> understand fatigue and corrosion issues in aluminum...
>
>
> Matt

My outrage is not whether the composites have a problem, but the method with
which they are to determine if there is a problem.

With some question (there must be a concern, hence an AD) there HAS to be a
better way than a tap test. It does nothing for my confidence.
--
Jim in NC

[Stefan]

Morgans wrote:

> there HAS to be a better way than a tap test.

Actually, no. Like it or not, but there are situations where the human
eye, ear and feel is still the most accurate method, if carefully done
by a skilled person, of course. (This is just a generic remark. I am no
specialist in composites at all and haven't the slightest clue what
problem airbus might or might not have.)

Stefan

[jsmith]

The "tap test", as used on fiberglass homebuilts, is used to detect
voids (air bubbles) in the epoxy/glass matrix. One usually uses a
Quarter to gently tap the surface. If there are any voids, the
difference in sound will be noticeable.

> Morgans wrote:
>> there HAS to be a better way than a tap test.

> Stefan wrote:
> Actually, no. Like it or not, but there are situations where the human
> eye, ear and feel is still the most accurate method, if carefully done
> by a skilled person, of course. (This is just a generic remark. I am no
> specialist in composites at all and haven't the slightest clue what
> problem airbus might or might not have.)

[George Patterson]

jsmith wrote:
>
> The "tap test", as used on fiberglass homebuilts, is used to detect
> voids (air bubbles) in the epoxy/glass matrix. One usually uses a
> Quarter to gently tap the surface. If there are any voids, the
> difference in sound will be noticeable.

How long do you think it will take to do this on an Airbus rudder?

George Patterson
I prefer Heaven for climate but Hell for company.

[C J Campbell]

"Helen Woods" > wrote in message
...
> And who was it insulting me earlier on this list for not wanting to fly
> plastic airplanes???

You were insulted for being completely ignorant of glass cockpits and making
utterly false and ridiculous statements about them, not plastic airplanes.
Near as I can tell you haven't learned much since then.

[C J Campbell]

"Morgans" > wrote in message
...
..
>
> A tap test? Is this is the best they can do to find possible flaws on
> multimillion dollar aircraft, carrying thousands of people around?

What is that? They whack it with a hammer to see if it breaks? What about
cracks and damage caused by the test?

[Dave S]

George Patterson wrote:
>
> jsmith wrote:
>
>>The "tap test", as used on fiberglass homebuilts, is used to detect
>>voids (air bubbles) in the epoxy/glass matrix. One usually uses a
>>Quarter to gently tap the surface. If there are any voids, the
>>difference in sound will be noticeable.
>
>
> How long do you think it will take to do this on an Airbus rudder?
>
> George Patterson
> I prefer Heaven for climate but Hell for company.


Use a Half Dollar then... and pack a lunch..

Dave

[Montblack]

("C J Campbell" wrote)
>> A tap test? Is this is the best they can do to find possible flaws on
>> multimillion dollar aircraft, carrying thousands of people around?
>
> What is that? They whack it with a hammer to see if it breaks? What about
> cracks and damage caused by the test?


I read that composites don't show cracks, instead they have weak 'air
pocket' spots that can't be seen during inspections. These pockets of air
bubles(?) are caused by heat/cold to the composite structures over time.

Think early British Comet jets - we're learning as we go I guess.

Whack, whack, whack ...she's good to go.


Montblack - sorry no link

[Paul Tomblin]

In a previous article, "Montblack" > said:
>I read that composites don't show cracks, instead they have weak 'air
>pocket' spots that can't be seen during inspections. These pockets of air
>bubles(?) are caused by heat/cold to the composite structures over time.

My father, who was the Chief of Non-Metallic Materials at deHavilland
Canada said that this is bunk. Once the composite is made and given the
initial inspection, there is no way in hell they could delaminate like
that.


--
Paul Tomblin > http://xcski.com/blogs/pt/
We're the technical experts. We were hired so that management could
ignore our recommendations and tell us how to do our jobs.
-- Mike Andrews

[Matt Whiting]

Morgans wrote:
> "Matt Whiting" > wrote
>
>
>>True, but we don't have 50 years of experience with composites in
>>service. Who knows what their deterioration/age related failure modes
>>may be? Remember, it took a couple of fatal accidents to begin to
>>understand fatigue and corrosion issues in aluminum...
>>
>>
>>Matt
>
>
> My outrage is not whether the composites have a problem, but the method with
> which they are to determine if there is a problem.
>
> With some question (there must be a concern, hence an AD) there HAS to be a
> better way than a tap test. It does nothing for my confidence.

Sometimes the simple tests really are the best. Visual inspection by
human eyes is still used for a lot of things even though it is well
known to have lots of problems (variability among humans being one of
the biggest).

Matt

[dave]

Montblack - you said exactly what I was thinking - British Comets.

Dave
68 7ECA


Montblack wrote:
> ("C J Campbell" wrote)
>
>>> A tap test? Is this is the best they can do to find possible flaws on
>>> multimillion dollar aircraft, carrying thousands of people around?
>>
>>
>> What is that? They whack it with a hammer to see if it breaks? What about
>> cracks and damage caused by the test?
>
>
>
> I read that composites don't show cracks, instead they have weak 'air
> pocket' spots that can't be seen during inspections. These pockets of
> air bubles(?) are caused by heat/cold to the composite structures over
> time.
>
> Think early British Comet jets - we're learning as we go I guess.
>
> Whack, whack, whack ...she's good to go.
>
>
> Montblack - sorry no link

[Wallace Berry]

> True, but we don't have 50 years of experience with composites in
> service. Who knows what their deterioration/age related failure modes
> may be? Remember, it took a couple of fatal accidents to begin to
> understand fatigue and corrosion issues in aluminum...
>
>
> Matt

Composite materials are pretty well understood by now. The Airbus
problems are not going to be found to be inherent in the materials, but
ones of design and quality control.

My fiberglass glider (Glasflugel H301) has been in service for 41 years.
It has not even been refinished. Most people think it is nearly new when
they see it. The fiberglass has not delaminated anywhere on it, Although
the gelcoat is clearly deteriorating and it will need refinishing soon.
The bird flies regularly. I usually put at least 100 hours/year on it,
more if the weather permits. I flew it over 200 miles this past weekend.
It gets pretty rough treatment compared to most planes. Landing in rough
fields, continuous hard pullups into thermals, often making 2 g turns to
center tight thermal cores, extreme turbulence while mountain flying,
etc. Those wings have flexed through a lot of cycles. That model has
only about 8 AD's (in the US) on it. All concern the metal parts.

Lest you think I'm a 'glass chauvinist, I also have a rag, tube, and
stick airplane (Stits SA-6), and a half share of a 1958 Cessna 175.

--
Take out the airplane for reply

[Montblack]

("Wallace Berry" wrote)
<snip>
> My fiberglass glider (Glasflugel H301) has been in service for 41 years.
> It has not even been refinished. Most people think it is nearly new when
> they see it. The fiberglass has not delaminated anywhere on it, Although
> the gelcoat is clearly deteriorating and it will need refinishing soon.
> The bird flies regularly. I usually put at least 100 hours/year on it,
> more if the weather permits. I flew it over 200 miles this past weekend.
> It gets pretty rough treatment compared to most planes. Landing in rough
> fields, continuous hard pullups into thermals, often making 2 g turns to
> center tight thermal cores, extreme turbulence while mountain flying,
> etc. Those wings have flexed through a lot of cycles. That model has
> only about 8 AD's (in the US) on it. All concern the metal parts.


I wonder if OAT is a common denominator missing here?

I thought it was (FL350) cold cycles they were looking at?


Montblack

[Blueskies]

"Matt Whiting" > wrote in message ...
> Sometimes the simple tests really are the best. Visual inspection by human eyes is still used for a lot of things
> even though it is well known to have lots of problems (variability among humans being one of the biggest).
>
> Matt

But once someone knows what they are looking for it is very hard to beat...

[Don Tuite]

On Thu, 24 Mar 2005 01:07:28 GMT, "Blueskies"
> wrote:

>
>"Matt Whiting" > wrote in message ...
>> Sometimes the simple tests really are the best. Visual inspection by human eyes is still used for a lot of things
>> even though it is well known to have lots of problems (variability among humans being one of the biggest).
>>
>> Matt
>
>But once someone knows what they are looking for it is very hard to beat...
>
Way back in my aerospace days, the guy at the next desk had a casting
he used as an ashtray. (I said this was way back.) The casting had a
tiny crack, and right across the middle of the crack was the QC
inspector's stamp.

Don

[Blueskies]

"Don Tuite" > wrote in message ...
> Way back in my aerospace days, the guy at the next desk had a casting
> he used as an ashtray. (I said this was way back.) The casting had a
> tiny crack, and right across the middle of the crack was the QC
> inspector's stamp.
>
> Don

Which begs the question...were they certifying the crack or were they certifying the part?

[Dave]

Ummm.............. I must respectively differ..

My company also does some marine surveying, ( inspecting
pleasure boats in insuring and pre-buy situations).

Ans , yes, I have seen many examples of this "delamination" of
composiets... :(

....many cause factors, osmosis being the most common, poor
quality control/contamination during layup are others....

Dave

On Wed, 23 Mar 2005 03:02:04 +0000 (UTC),
(Paul Tomblin) wrote:

>In a previous article, "Montblack" > said:
>>I read that composites don't show cracks, instead they have weak 'air
>>pocket' spots that can't be seen during inspections. These pockets of air
>>bubles(?) are caused by heat/cold to the composite structures over time.
>
>My father, who was the Chief of Non-Metallic Materials at deHavilland
>Canada said that this is bunk. Once the composite is made and given the
>initial inspection, there is no way in hell they could delaminate like
>that.

[Don Tuite]

But isn;t that just gelcoat delam. Cosmetic, and it occurs by osmotic
pressure on parts of the hull submerged in salt water?

On Wed, 23 Mar 2005 23:07:09 -0400, Dave
> wrote:

>Ummm.............. I must respectively differ..
>
> My company also does some marine surveying, ( inspecting
>pleasure boats in insuring and pre-buy situations).
>
> Ans , yes, I have seen many examples of this "delamination" of
>composiets... :(
>
> ....many cause factors, osmosis being the most common, poor
>quality control/contamination during layup are others....
>
> Dave
>
>On Wed, 23 Mar 2005 03:02:04 +0000 (UTC),
>(Paul Tomblin) wrote:
>
>>In a previous article, "Montblack" > said:
>>>I read that composites don't show cracks, instead they have weak 'air
>>>pocket' spots that can't be seen during inspections. These pockets of air
>>>bubles(?) are caused by heat/cold to the composite structures over time.
>>
>>My father, who was the Chief of Non-Metallic Materials at deHavilland
>>Canada said that this is bunk. Once the composite is made and given the
>>initial inspection, there is no way in hell they could delaminate like
>>that.

[Stefan]

Dave wrote:

> ....many cause factors, osmosis being the most common

This would have to be a pretty wet climate for osmosis to happen on an
airplane...

Stefan

[Paul Tomblin]

In a previous article, Dave > said:
> Ans , yes, I have seen many examples of this "delamination" of
>composiets... :(

It would be easier to understand or give credence to your points if you
knew how to spell or punctuate.

> ....many cause factors, osmosis being the most common, poor
>quality control/contamination during layup are others....

Osmosis happens to things immersed in salt water, which hopefully isn't
the case with aircraft rudders. And the "poor quality
control/contamination during layup" are why I specified that these things
would be caught in the initial inspection. Aircraft parts are subject to
a lot more quality control and tougher inspections that your boats.

Anyway, I suspect you are seeing cosmetic flaws in the gelcoat, not full
on structural failures.


--
Paul Tomblin > http://xcski.com/blogs/pt/
I've never understood why women douse themselves with things that are alleged
to smell of roses/tulips/freesias. What exactly are they trying to attract?
Bees? -- Tanuki

[Colin W Kingsbury]

"Paul Tomblin" > wrote in message
...
> In a previous article, Dave > said:
> > Ans , yes, I have seen many examples of this "delamination" of
> >composiets... :(
>
> It would be easier to understand or give credence to your points if you
> knew how to spell or punctuate.
>
> > ....many cause factors, osmosis being the most common, poor
> >quality control/contamination during layup are others....
>
> Osmosis happens to things immersed in salt water, which hopefully isn't
> the case with aircraft rudders. And the "poor quality
> control/contamination during layup" are why I specified that these things
> would be caught in the initial inspection. Aircraft parts are subject to
> a lot more quality control and tougher inspections that your boats.

Usenet grammar pedants should beware of preposition-object agreement in
their glass houses ;)

> Anyway, I suspect you are seeing cosmetic flaws in the gelcoat, not full
> on structural failures.

In many older boats, osmotic blistering is going beneath the gelcoat,
sometimes several layers deep. However, I tend to agree that we are talking
apples and oranges here. The worst blistering is found on boats going back
into the 60s and 70s, and drops off with each passing year as manufacturers
understood layup better. Airbus started using composites in the early 80s,
by which time we were starting to get a decent feel for best practices in
manufacturing.

-cwk.

[Ben Smith]

> Way back in my aerospace days, the guy at the next desk had a casting
> he used as an ashtray. (I said this was way back.)

<Drifting OT to talk about the days of smoking in the workplace>

When I worked as a computer operator not long ago, the master console
keyboards were the same ones used by many generations of operators before
me. They were all stained yellow from the cigarette smoke. My supervisor
(who was working there back then) was talking about the 'good ole days' when
they had an ashtray next to every keyboard. :)

[jsmith]

The "industrial" version of this is an ultrasonic probe which is passed
over the surface. (Sort of like the OB/GYN's ultrasound device).

> jsmith wrote:
>>The "tap test", as used on fiberglass homebuilts, is used to detect
>>voids (air bubbles) in the epoxy/glass matrix. One usually uses a
>>Quarter to gently tap the surface. If there are any voids, the
>>difference in sound will be noticeable.

> George Patterson wrote:
> How long do you think it will take to do this on an Airbus rudder?

[Dave]

Unfortuntely, no.....

To often, it goes very deep, and has caused entire hulls to be
replaced or otherwise discarded... :(

Repairs are very expensive, usually requiring grinding out the
affected area, thorough drying, reinstalling the glass laminations and
resurfacing/finishing etc.

It can happen in salt, brackish and fresh water, and is worse where
there is a freeze/thaw cycle in areas that have freezing temps during
layup...

I have discovered it in vessels that have only been operated in
fresh water.

I see less of it now, manufacturing techniques/quality control has
generally improved. There was a bad stretch during the '70's
and'80's...

Other cases have been topside cracks that have allowed water to
penetrate into an unsaturated laminate (usually at a corner of a
structure) freeze and open the delamination further.This can also
become a structural issue.. :(

Cheers!

Dave

On Thu, 24 Mar 2005 05:38:19 GMT, Don Tuite
> wrote:

>But isn;t that just gelcoat delam. Cosmetic, and it occurs by osmotic
>pressure on parts of the hull submerged in salt water?



>
>On Wed, 23 Mar 2005 23:07:09 -0400, Dave
> wrote:
>
>>Ummm.............. I must respectively differ..
>>
>> My company also does some marine surveying, ( inspecting
>>pleasure boats in insuring and pre-buy situations).
>>
>> Ans , yes, I have seen many examples of this "delamination" of
>>composiets... :(
>>
>> ....many cause factors, osmosis being the most common, poor
>>quality control/contamination during layup are others....
>>
>> Dave
>>
>>On Wed, 23 Mar 2005 03:02:04 +0000 (UTC),
>>(Paul Tomblin) wrote:
>>
>>>In a previous article, "Montblack" > said:
>>>>I read that composites don't show cracks, instead they have weak 'air
>>>>pocket' spots that can't be seen during inspections. These pockets of air
>>>>bubles(?) are caused by heat/cold to the composite structures over time.
>>>
>>>My father, who was the Chief of Non-Metallic Materials at deHavilland
>>>Canada said that this is bunk. Once the composite is made and given the
>>>initial inspection, there is no way in hell they could delaminate like
>>>that.

[Dave]

Yes, it would have to be VERY wet! :)

Stress cracks, or gel coat cracks penetrated by rain/melting snow and
freezing during winter would be interesting though...

Cheers!

Dave

..On Thu, 24 Mar 2005 11:58:18 +0100, Stefan >
wrote:

>Dave wrote:
>
>> ....many cause factors, osmosis being the most common
>
>This would have to be a pretty wet climate for osmosis to happen on an
>airplane...
>
>Stefan

[Dave]

On Thu, 24 Mar 2005 14:12:54 +0000 (UTC),
(Paul Tomblin) wrote:

>In a previous article, Dave > said:
>> Ans , yes, I have seen many examples of this "delamination" of
>>composiets... :(
>
>It would be easier to understand or give credence to your points if you
>knew how to spell or punctuate.



Agreed, (I hate laptop keyboards!) Fortunately, I am a better with
survey tools than a keyboard.

I see you have a similar problem...

"and tougher inspections that your boats."

(your paragraph below)


>
>> ....many cause factors, osmosis being the most common, poor
>>quality control/contamination during layup are others....
>
>Osmosis happens to things immersed in salt water, which hopefully isn't
>the case with aircraft rudders. And the "poor quality
>control/contamination during layup" are why I specified that these things
>would be caught in the initial inspection. Aircraft parts are subject to
>a lot more quality control and tougher inspections that your boats.

Osmosis causes problems in salt, brackish and fresh water. If freeze /
thaw cycles are present after ANY moisture penetrates, delamination
will continue, and can cause structural damage in any composite.
>
>Anyway, I suspect you are seeing cosmetic flaws in the gelcoat, not full
>on structural failures.

Unfortunately, no. Entire hulls/boats have been condemmed due to this
problem in severe cases. Most are repairable, although repairs are
very costly. Physical inspection can uncover most problems, but the
x-ray equipment tells the whole story...

And the inspection process for high performance racing hulls rivals
the aircraft testing techniques, including full hull x-ray
inspections...

Thanks for your reply..

Dave

[Dave]

Agreed Colin..

Worst years were during the 70's - 80's,- 10 yr old boats built in
late 60's / early 70's...

....Also in some boats built with the fire retardant resin called
"Heteron" (sp?) during late 70's.....

Agreed...much has been learned about building composites since
then....

Also agreed, apples /oranges here ... however, a crack in a fiberglass
cowl a few yrs ago caused water from melting snow to penetrate the
laminate on an aircraft here. (Stored outside) The freeze/thaw cycle
caused a delamination about the size of an adult hand. It started
around a fastener mount..This was easily spotted through the
transparent inner laminations when viewed from the inside..(once the
cowl was removed) and easily repaired...

Cheers!

Dave


On Thu, 24 Mar 2005 16:28:04 GMT, "Colin W Kingsbury"
> wrote:

>
>"Paul Tomblin" > wrote in message
...
>> In a previous article, Dave > said:
>> > Ans , yes, I have seen many examples of this "delamination" of
>> >composiets... :(
>>
>> It would be easier to understand or give credence to your points if you
>> knew how to spell or punctuate.
>>
>> > ....many cause factors, osmosis being the most common, poor
>> >quality control/contamination during layup are others....
>>
>> Osmosis happens to things immersed in salt water, which hopefully isn't
>> the case with aircraft rudders. And the "poor quality
>> control/contamination during layup" are why I specified that these things
>> would be caught in the initial inspection. Aircraft parts are subject to
>> a lot more quality control and tougher inspections that your boats.
>
>Usenet grammar pedants should beware of preposition-object agreement in
>their glass houses ;)
>
>> Anyway, I suspect you are seeing cosmetic flaws in the gelcoat, not full
>> on structural failures.
>
>In many older boats, osmotic blistering is going beneath the gelcoat,
>sometimes several layers deep. However, I tend to agree that we are talking
>apples and oranges here. The worst blistering is found on boats going back
>into the 60s and 70s, and drops off with each passing year as manufacturers
>understood layup better. Airbus started using composites in the early 80s,
>by which time we were starting to get a decent feel for best practices in
>manufacturing.
>
>-cwk.
>