Hi Jeff,
I think we are basically in agreement. But pre-drilling the holes in my view
is absolutely essential.
If you make a tiny mistake in drilling after the installation you will have
to start all over again, and you won't have a 100% accurate reference for
the holes and angle.
Regards,
Karl
>From: Jeff B <topglock@cox.net>
>Reply-To: europa-list@matronics.com
>To: europa-list@matronics.com
>Subject: Re: Europa-List: Europa Tailplane - Mod 73
>Date: Sun, 15 Jul 2007 16:25:18 -0500
>
>
>Karl,
>
>The particulars on aligning and drilling the pip pin holes should not be a
>big problem. It may be as simple as marking cross hairs on the surface of
>the tailplane or, building a template using a plastic tube and end plate,
>simulating the drive plate, should allow you to get a precise enough
>measurement to drill the holes. If you've built in a drain hole, as
>provided for in the instructions, the lower hole should be a breeze. At
>any rate, I see it as a doable mod and one that should provide a much
>stronger tailplane.
>
>Jeff
>
>Karl Heindl wrote:
>>
>>
>>Jeff,
>>
>>I think that the TP5 and TP6 can be removed with heat without cutting any
>>holes. Also, it would be easier to pre-drill the pip-pin holes, as you
>>can then do a trial fit before bonding. To get the position exactly right
>>I would attach a template (using double-sided tape) with a 1/4 inch hole
>>over the top of the recess, first lining up all 3 holes with a 1/4 inch
>>shaft or bolt, before removing the TP6. Just one of my crazy ideas.
>>
>>Karl
>>
>>
>>
>>
>>
>>>From: Rman <topglock@cox.net>
>>>Reply-To: europa-list@matronics.com
>>>To: europa-list@matronics.com
>>>Subject: Re: Europa-List: Europa Tailplane - Mod 73
>>>Date: Sun, 15 Jul 2007 13:25:12 -0500
>>>
>>>
>>>All,
>>>
>>>I've read, with great interest, all the suggestions and discussion. I'm
>>>no engineer, but I have a pretty good idea of what I would do, should I
>>>find any evidence of disbonding of the tailplane bushings. And, I
>>>believe it could be done with very little cosmetic damage to the
>>>tailplane. I like the solid tube idea and would build off of that.
>>>Basically, a tube, of the appropriate length, with two 1/4", round, metal
>>>rods welded fore and aft, on centerline. The rods wouldn't have to run
>>>the full length of the tube, but it certainly wouldn't hurt. The purpose
>>>of the rods would be to further stabilize the tube and prevent it from
>>>twisting.
>>>
>>>Should the original bushings become disbonded, it should be a fairly
>>>simple task to remove the old bushing (even if it required opening the
>>>wingtip), remove the inner bushing and modify the foam and ribs, to
>>>accomodate the new shape of the tube. Inserting the new tube would be as
>>>simple as applying a thin coat of Redux to the tube and inner walls of
>>>the foam, plugging the outboard end of the new tube and pushing the
>>>assembly in. The new tube would then be drilled to accept the standard
>>>pip pins. Adding covers to the pip pin access holes would further remove
>>>the possibility of a pin becoming dislodged.
>>>
>>>Seems to me that the new assembly would be extremely strong and should
>>>remove any further chance of the tailplanes pulling away from the drive
>>>pins.
>>>
>>>So, am I way off base, of does this idea hold water?
>>>
>>>Jeff - Baby Blue
>>>300 hours and finishing up her 2nd annual...
>>>
>>>Karl Heindl wrote:
>>>>
>>>>
>>>>
>>>>
>>>>Nigel,
>>>>
>>>>I understand all that and your mod should have been made standard a long
>>>>time ago. But what about older Europas ? We hear reports about disbonded
>>>>TP6s but we don't hear how they were repaired. I really would like to
>>>>know. A suitable retrofit mod should also have been made available as
>>>>soon as this problem was known.
>>>>I still say that there is no way the tailplane can move if the pip pin
>>>>head is firmly against solid material on the inboard side. You say there
>>>>is always a gap, but that gap is filled with floxed epoxy, and the head
>>>>is inside a close fitting plastic pipe in my case. I think another
>>>>builder recently told us about a similar mod he made. The remaining
>>>>space around the pipe is also filled with epoxy. Of course all these
>>>>solutions are based on theory and only a lab test could verify the
>>>>claims.
>>>>When my TP5s disbonded from trailering I was kicking myself for not
>>>>having installed a one-piece pipe, but in those early days I was very
>>>>careful to follow the build instructions precisely. I stll think that a
>>>>retrofit of a one-piece sleeve would be more than strong enough to
>>>>prevent any future disbonding, and would be a relatively easy solution
>>>>where the TP6s have already disbonded.
>>>>
>>>>As far as the accident goes, we still don't have any real conclusive
>>>>evidence about the sequence of events. Only a number of theories. Only a
>>>>wind tunnel test would verify the flutter theory, but who is going to
>>>>pay for that ? Eyewitness reports can be very misleading.
>>>>If the wing trailing edge pin came off first, is it possible that the
>>>>pilot was getting set up for landing and deploying flaps and
>>>>undercarriage ?
>>>>
>>>>I also like the other suggested solutions where a lock is put behind the
>>>>TP12
>>>>
>>>>
>>>>Karl
>>>>
>>>>
>>>>>
>>>>>
>>>>>
>>>>>Karl,
>>>>>
>>>>>I have attached below, an excerpt of a long mail I sent to the PFA that
>>>>>describes a sequence of events that could lead to the tailplain moving
>>>>>outboard. Out of interest, there is always a gap between the pip-pin
>>>>>and the
>>>>>face of the rib.
>>>>>
>>>>>This was sent before the current Mod 73 was issued, but you will see
>>>>>why the
>>>>>temporary remedial action has been to reinforce the pip-pin hole.
>>>>>
>>>>>Nigel
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>-------------------------------
>>>>>Excerpt
>>>>>
>>>>>...... The only thing preventing each tailplane moving sideways is a
>>>>>single
>>>>>pip-pin that passes through the TP6 bush and into the TP4 torque tube.
>>>>>(See
>>>>>Fig.5 Chap 4)
>>>>>The design relies on a good bond to hold TP6 in place, however only the
>>>>>protruding outer 12mm (just 8mm on TP5) is required to bond to the
>>>>>tailplane
>>>>>rib that will subsequently be laid-up onto it. Epoxy adhesive does not
>>>>>bond
>>>>>well to stainless steel - so the potential for this bondline to fail is
>>>>>great.
>>>>>This tiny bondline is the only "design" load path to prevent the
>>>>>tailplane
>>>>>moving laterally. If the bond failed, the loose TP6 bush would tend to
>>>>>push
>>>>>its way inboard into the soft blue foam, allowing the tailplane to move
>>>>>outboard. The TP5 bush would offer no resistance since it would simply
>>>>>slide
>>>>>along the TP4 torque tube.
>>>>>
>>>>>In some early Europas, this TP6 bush has de-bonded and it is only the
>>>>>laminations into the "PipPin" access hole that prevent any lateral
>>>>>movement
>>>>>of the tail-plane. This lamination was never intended to be structural.
>>>>>If
>>>>>the aircraft is high-time and habitually operated off rough strips, it
>>>>>is
>>>>>logical to predict that the continual fretting would cause the glass
>>>>>around
>>>>>the pip-pin hole to chafe, opening up the hole to a point where the
>>>>>whole
>>>>>tailplane could slide far enough laterally to allow the tail-pane drive
>>>>>pins
>>>>>(TP12) to disengage from their drive bushes (TP13) - The tailplane
>>>>>would
>>>>>then oscillate violently with catastrophic results.
>>>>>
>>>>>Modification 10672) calls for both the Stainless TP5 and TP6 bushes to
>>>>>be
>>>>>laminated into an epoxy/Bi-Directional Glass tube before inserting this
>>>>>into
>>>>>the tailplane TP2 cores and laminating the ribs. This bonds both bushes
>>>>>over
>>>>>their entire surface area, significantly increasing the bond area and
>>>>>more
>>>>>importantly, physically tying TP5 with TP6 and both the inner and outer
>>>>>ribs
>>>>>together. With this structure, the entire bond surface area and both
>>>>>ribs
>>>>>would have to fail before the tailplane could move sideways.
>>>>>
>>>>>The loadpath is through the mod 10672 and not through the outer skin
>>>>>and
>>>>>pip-pin hole - a significantly better engineering solution.
>>>>>
>>>>>
>>>>>-
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>_________________________________________________________________
>>>>Watch all 9 Live Earth concerts live on MSN.
>>>>http://liveearth.uk.msn.com
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>
>>_________________________________________________________________
>>Watch all 9 Live Earth concerts live on MSN. http://liveearth.uk.msn.com
>>
>>
>>
>>
>>
>>
>>
>
>
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