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.
>>>>
>>>>
>>>> -
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>> _________________________________________________________________
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>>> http://liveearth.uk.msn.com
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>
> _________________________________________________________________
> Watch all 9 Live Earth concerts live on MSN. http://liveearth.uk.msn.com
>
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