Not quite sure what happened - this got lost.
----- Original Message -----
From: "Carl Pattinson" <carl@flyers.freeserve.co.uk>
Sent: Tuesday, July 17, 2007 6:23 PM
Subject: Re: Europa-List: Europa Tailplane - Adequate Design?
> >
>> 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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