Re: BROKEN SPAR


JohntenHave <Jtenhave@...>
 

Guys,

this is a very disturbing report and needs to be investigated
properly.

May I suggest that as an absolute minimum and with immediate effect
everyone with LS-1 canards who has arbitrarily increased their gross
weights reduce the limits to the published limits. The highest
stress that the spar sees will occur with a mauw heavy landing (
Anyone prepared to bet they will not have a MAUW EFATO one day?)

Ideally, do not fly until more is known, Less ideally, fly one up
and fly conservatively. (airracers, listen up!) If you are immortal
or wish to become so, ignore this completely. The only exception
could be Jim Patillo but the integrity of his unmodified spar is
possibly still in question.

James' experience is consistent with a spar that had partially failed
prior to the last landing, had sufficient residual strength to cope
with the distributed loads of normal flight but when subjected to the
same load applied to the mains, (i.e. a point load on the end of a
cantilever) failed completely.

When Jim P's spar failure was detected it was as a result of really
diligent examination in an area which was not the easiest to see.
Unless one had a really heavy landing and heard something the chances
of picking up the surface indications where he found them are very
low. He did a great job finding it.

The nature of carbon failure is that (for symmetrical section spars
such as that used in the Q 200) it will fail in compression first
when the spar is loaded in a manner such as that employed for the
initial testing. Compression failures can be less obvious than
tensile failures in carbon.

James,

firstly I am glad that you are still with us. Secondly, you have
done the Q community a great service by letting everyone know what
happened to you. Well done!

May I suggest that you measure carefully from the center of the spar
to where the failure occurred. Jim's spar failed at BL12 from memory.
If your failure is located in the same place you may be flying
another spar which failed during test but was either not detected or
not discarded. Take as many photos as you can.

If it is a similar failure, an inspection procedure will have to be
developed - and I have given some thought to appropriate NDT methods.

Some options:

The simplest may be a magnified visual examination, the next may be
a stethescope on the suspected site with a loading designed to flex
the area, if facilities permit, an ultrasound examination of the
suspected area and the most complex may be a boroscopic or hi res
video internal examination from the outboard end.

For those who are still building, or about to begin Q-200s, do what
ever is required to thoroughly examine the inside and outside of the
spars for any signs of damage. The stock spars are very thin and
damage intolerant.

Either way, this is two primary structure failures too many and two
very lucky escapes. The chances of a latent fatal waiting to happen
are too high to ignore. Stated bluntly, Q-200s are inherently risky
aircraft to operate in their present state. The risk needs to be
reduced.

I suggest that in the medium term, the least that should be done is
to statically load test each aircraft to a load sufficient to verify
structural integrity within the desired flight envelope.

An alternate strategy (conservative) is to assume that every spar has
the flaw and design a repair scheme that applies a suitable repair to
the site of both spars. Jim has documented his repair very well and
it would not be twice the work to repair both spars at the same time.

A third approach (most conservative) would be to declare all canards
with existing carbon spars suspect and decide to build new ones with
replacement spars.

If I can be of help, James, let me know.


John ten Have
SAAA Tech Councillor

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

snipped for bandwidth (not for content!)


Mike,
SPAR

Hello Group,

I had a landing accident at Chino on April 21 which resulted in
a
broken
spar.

This was in a Q2 with the LS-1 canard. It broke just inside the
fuselage on
the right side in the area that Jim Patillo has repaired on his
airplane.

The landing was smooth and the right canard did not impact
anything. I
swerved right, then left, then right and the spar broke. When
the
aircraft
settled to the ground, it ground looped to the right 200 degrees.

The NTSB and the FAA is investigating. I asked the FAA accident
investigator if they would take any action regarding the
airplane
type and
he said that seeing as it is experimental, it is up to the
owner/builders to
take some action. There probably will be an NTSB accident
report
as there
was substantial damage to the airplane. I was not injured.

The airplane does not have the wheel alinement.

If you want to comment on this, please send mail to me as well
as
to the
list as I am not getting mail from the list. Telephone calls
are
also O.K.

James Postma
Steilacoom, Washington
(253) 584-1182 9:00 to 8:00 PDT


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