Re: Old Timers and repair options


JohntenHave <Jtenhave@...>
 

Jim,

let me put aside your bullying and address the issues you raise.

I too believe there may be a problem but with a lot more emperical
data on this airframe/spar than you posess. We pilots flying
LS1s'are
living in the environment, you are viewing it from a distance.
Agreed! So what? I do not have to face the possibility that my
aircraft may be unsafe, and that it may be expensive to fix, or that
I may have been operating it in a manner which endangered my pax. I
have no face saving implications colouring my comments, Jim.

You
make the coment "at least half of your spar "is sound so far", you
don't know that so don't make that statement.

That is is the issue Jim, WE do not know for sure, either way. You
have repaired one side with a repair that we discussed (perhaps you
have forgotten your phone call to me discussing the way forward?) A
repair scheme that I endorsed after I sought expert advice upon it
on your behalf (perhaps you have forgotten?) so there is a
reasonable degree of confidence that the repaired side is fine. My
question is this : what about the other side? What if it has a
latent flaw which is progressing at a slower rate because it is
located in a slightly less vulnerable orientation?

In retrospect I should have recommended you repair the other side at
the same time.


The point is I didn't "overload" my airframe before I had a
failure.
The airframe never saw loads above those published during those
initial hours and I was very sensitive to the loads on my plane,
CG
and otherwise during the flight test phases. It's never had a hard
landing or even been sideways on the runway.
In a way this is even more disturbing, if it failed after only
seeing moderate loads - but that is typical of fatigue failures or
progressing defects - nothing, nothing, nothing, failure. Right up
to the last nothing, all indications are that the airframe is sound
unless someone looks in the right place for the right thing.

Since that time several
of us have flown regulary with higher gross weights. Bob Farnam,
Bob
Malechek, Phil Lankford with a "K", myself and others.
Hmmm, how many nothings have been used up then, do you think? Maybe
there is no flaw in their airframe? But what if they have the same
flaw as you had but have yet to discover it? What would responsible
advice be to such owners? Mine is this - sit it on the ground until
you know for sure what you have. At the very least stick to the
design limits.

If you cannot answer the question "how much margin did the designer
build into this design?" There is no logical or safe basis for
exceeding the limits.


Why haven't
more of those airframes failed?
See above.

I suspect the reason you haven't heard from any "old timers" is
they
have been paying attention and checking their spars and don't even
want to enter this kind of exchange with someone who "isn't
involved"
directly.
Maybe, and more power to them if they are. If this discussion
serves only to prompt that action we have advanced the cause of Q-
200 flight safety.

Isn't it interesting you are now raising and making a big
deal out of these concerns two years after I made them public.
The game has changed Jim. This is not primarily about your airframe.
It can no longer be dismissed as an isolated incident. you are
right, It is interesting and very serious. No amount of bravado
will change that.

Where
were you then when Bob Farnam and I came up with the fix for the
spar? Where were you when I did the initial flight testing?
you have a conveniently short memory Jim.

Where
were you when I wrote the article to alert others to the possible
problem?
I suspect that I was on the sidelines happy that your event and the
fix was being documented in some manner.


What has prompted you to come out on this subject again??
Come on Jim, James Postma's report means this is a possible fleet
problem.



That said, You've raised concerns that are valid and people are
listening. For that I thank you. Now if you're so capable come up
with a plan of assessment that is simple and can be done
reasonably
easy and I don't mean static loading it til you really do
overstress
the frame!

Jim, as I have taken some time to explain, the problem is not simple
to assess in a manner which picks up all the defect options and
without requiring a significant repair effort. Why are you afraid of
static loading Jim? Is it because it may yield a result no one wants?

Advice?

Based upon the assumption that James spar has failed in the same
place and due to the same mechanism as yours...

Right now for uninstalled spars I suggest four things, inspect
carefully. Reinforce the area with an equivalent strength doubler,
replace them with know good spars or install them assuming a defect
and extend the central splice beyond the site of the defect.

For installed spars I have provided the inspection options in a
previous post. If a defect is found : two options, repair and the
simplest is to simply extend the center splice doublers at full
strength beyond BL 12 left and right and then taper as per plans.

Less simply, you could excavate down to the carbon, apply a carbon
uni doubler and then repair the splice at 1" per layer. This is not
trivial because nobody knows for sure what materials have been used
or what the exact layup schedule is. A burn test is unhelpful.

For installed spars with no defect found, there is not enough
information yet to give informed advice.

regards

John

(cheerfully unbullied!)










Jim

"JohntenHave" <Jtenhave@m...> wrote:
Well Jim,

As OJ once said, "I will have stab at this one"

You get marks for optimism! That said, yours is one of the
failed
airframes which has been subsequently repaired. At least half of
your
canard spar is sound - so far! Here is the question you should
ask,
then answer, Jim.

"What would responsible advice be to someone who had an
identical
failure to yours but had yet to detect it?"

In the absence of positive proof to the contrary, there is a real
risk
that there are more of these spars out there. I agree that this
is
an
issue of uncertainty but that is the nature of the beast.

In no particular order I suggest that the silence (and I agree,
it
is
deafening)could be due to:

a. the fact I am completely wrong in interpreting two primary
structural failures in a fleet of (how many?) flying airframes
as
flight critical safety issues which would ground civilian
fleets.
(anyone want to put bet with their life?)

b. Different risk perceptions between engineers and pilots.

c. Lack of understanding of failure consequences.

d. Failure to admit that the Q-200 airframe is not as safe as
previously assumed.

e. The problem is not correctly understood.

f. The SMS*

g. don't give a damn

You make a good point about high hour airframes but let me
qualify
it.

500 hrs + may mean that they have inadvertently verified their
spars
as sound OR they may not have overloaded their airframes as you
have
done and the residual structure may still be holding. It may
also
be
that their flaws are located in an area closer to the neutral
axis
and
therefore the defect is progressing at a slower rate. It may
also
be
that the failure mechanism in James's airframe differs from
yours,
but
that will be cold comfort as a new Q 200 speed record is set in
the
vertical.....

What does this mean? It might mean this is just too hard so
let's
not
look and maybe it will go away. It might mean that the Q-200 is
a
high
risk airframe to fly but owners do not want the face the hard
facts.

This can be fixed guys, but before it is fixed the problem needs
to
be
acknowledged, defined, the cause verified and repair schemes
developed.

In the meantime it is terribly unwise to overload this airframe,
the
faith you place in it is not justified.

Regards

John

* Stunned Mullet Syndrome



--- In Q-LIST@..., "Jim Patillo"
<logistics_engineering@m...> wrote:

Its kind of interesting that none "not one of the guys" with
over
500
hours on the LS1 spar clock have spoken up. What does this
mean?

Jim P. Heading for
Watsonville Airshow this Weekend!

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