>
> Carl, I think it's not correct to say that time has found the design to be
> inadequate.
William,
I cant think of another way of summarising the "problem" other than to say
that the TP6 installation has proved inadequate. What is certain is that if
we knew then what we knew now the design would have been substantially
different.
IMHO the attachent of the TP6 sleeve to the structure isnt as robust as it
could be and like several others I had concerns at the time over the manner
in which it was bonded to the tailplane. Many builders took steps to improve
the adhesion of the ring to the surrounding structure. In my case I scored
the ring with a hacksaw at 45 degrees around the circumference. Whilst I
never understod the implications of this component becoming disbonded I just
felt from an engineering standpoint that it wasnt very good.
In all other respects I agree totally with everything you said. The fact
that David Corbett found all the TP6 attachments rock solid is encouraging.
As I have said elsewhere I suspect that 99% of our aircraft are safe in this
respect but even a 1% failure rate is unaccepable.
Also thanks for explaining Williams pip pin setup - I wasnt aware it was so
different.
Like you I intend to continue to enjoy flying my Europa and have every
confidence in the aircraft.
Regards
Carl
>William's plane in one critically important respect was not
> built to design. He did not have a standard pip pin recess, but instead a
> hole rather like the undersurface drain hole, down which he fished with a
> sort of crochet hook to get the pin out
> William was intelligent, thoughtful and meticulous and also had
> more aeronautical engineering experience than nearly all of us, but the
> redesign of that area meant that he had no sensible way of checking the
> security of TP6 bonding, and also that there was nothing but foam to stop
> the tail plane migrating once a TP6 did disbond. Also he regularly
> dismantled his plane, so possibly was at greater risk of the TP6 becoming
> disbonded by repeated impact on the end of the torque tube.
> Like many of those who have contributed I felt considerable unease
> until I had an explanation for the known events: that is that the tail
> elements broke up/off while he was in level flight at 1000 ft and 100 kts
> or
> thereabouts, when it appears that there had been no problems with him
> having
> previously done his renewal test flying including a Vne dive. Flutter
> starting out of the blue a t such a speed made no sense when we know much
> of
> the fleet has varying degrees of slop yet regularly survive Vne
> dives.However the loosening of a TP6 with uncoupling of the tailplane
> drive
> pins is an entirely plausible explanation for the events as so far known,
> and makes me feel entirely comfortable with my plane again.
> As far as the solution goes I also disagree that it is a mere
> 'sticking plaster'. If the pip pin recess is as designed we can readily
> check the position and any movement of the TP6. To have shifted the tail
> plane laterally in relation to the pinned TP6 would entail tearing the pip
> pin through a visible fibreglass lay up and would have needed
> considerable
> force. To pull a TP6 disbonded from the rib through the upper lay up and
> the
> new underside lay up would, I strongly suspect, take several hundred
> pounds
> force - yet there are no strong lateral forces naturally occurring on the
> tail plane. On doing mod 73 I found my TP6 to be rock solid in the rib on
> each side, as indeed David Corbett reported for the three he has done.
> I for one will continue to enjoy flying my plane with the same
> confidence it has always given me (which is more than the confidence I
> have
> felt in various certified planes I have flown over the same period).
> Regards, David Joyce, G-XSDJ
>
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