Hi Nigel
Yes, thank you for the additional detail. Bt you still don't say HOW the TP4
is to be cleaned out. And you say that the mass balance arm has to be
disconnected. That means having to crawl into the tail section and
performing all kinds of difficult tasks. My balance arm is very tight and
that was easy to do with the top off. I don't really want to touch it. I am
also not rushing into mod 70.
And as Mark and others have remarked: we don't really know anything about
the accident. Except, that a wing landed on the road, the main fuselage in a
field, that at least one tailplane came off initially, and a pip pin was
bent 90 degrees. Obviously something started the chain of events from the
tail somewhere. There may or may not have been any flutter. I guess we'll
find out a bit more in a week or so.
I like the idea of doing away with the mass balance arm, and weighting the
tailplanes internally, at least for new kits.
Karl
>From: "Nigel Graham" <nigel_graham@btconnect.com>
>Reply-To: europa-list@matronics.com
>To: <europa-list@matronics.com>
>Subject: RE: Europa-List: Tailplane flutter
>Date: Mon, 25 Jun 2007 13:59:25 +0100
>
><nigel_graham@btconnect.com>
>
>Hi Karl,
>
>You're clearly thinking this through!
>
>My description was only an abstract to give an idea of the concept.
>The detailed proposals handle preparation insertion and bonding.
>
>Here is a description for those of you with an enquiring mind - I will not
>take offence if the rest of you skip this!
>
>TP4 has to be de-greased and de-burred inside prior to insertion. The discs
>have a scribe line on one side to indicate the orientation of the cross
>drill (facilitating alignment). You were on the money with regard to the
>insertion tool. A 6.0mm threaded bar (with two lock nuts) screws into a
>central hole in the disc. This allows the discs to be inserted into TP4 and
>rotated into correct alignment - two from one side and two from the other.
>
>The discs have a shallow groove centrally around the circumference. Once in
>position, bearing grade anaerobic adhesive (Loctite) is introduced through
>one of the TP4 holes and the discs rotated to distribute the adhesive. This
>ensures concentricity and accommodates any small variance of inside
>diameter.
>An AN4 bolt can be temporally inserted to locate the disc in the correct
>position and the thread bar removed. In this way, all four discs are placed
>and bonded. The 6mm holes also serve to cross vent the tube and provide a
>method (via spray tube) of introducing the anti-corrosion treatment of your
>choice (ACF50, WD40, Shell "Ensis" fluid, granny's beef dripping) into TP4.
>
>Once bonded, the tail can be re-assembled. The bolts have to be inserted
>from the rear to guarantee clearance with the rear bulkhead. This will
>involve rotating the TP4 assy up through 90 degrees to allow the bolts to
>be
>inserted from underneath. (The counter balance arm needs to be removed
>first). It does have the advantage that the castellated nuts and split pins
>can be inserted from the front of TP4 and not tucked behind as in the TP14
>assembly instructions.
>
>Hope this answers some of you (good) questions.
>
>Nigel (The other one)
>
>-----Original Message-----
>From: owner-europa-list-server@matronics.com
>[mailto:owner-europa-list-server@matronics.com]On Behalf Of Karl Heindl
>Sent: 25 June 2007 12:30
>To: europa-list@matronics.com
>Subject: RE: Europa-List: Tailplane flutter
>
>
>Hi Nigel,
>
>My main concern with this mod would be the insertion of the (predrilled)
>15mm discs into a tube with anti-corrosion paint on the inside. Would there
>be a suitable reamer to get it absolutely smooth, also to remove any burr
>from the enlarged holes. Then how do you aim to position the discs so that
>all the holes line up ? Maybe a threaded hole in the centre for attaching a
>long rod temporarily just for the lineup ?
>
>Karl
>
>
> >From: "Nigel Graham" <nigel_graham@btconnect.com>
> >Reply-To: europa-list@matronics.com
> >To: <europa-list@matronics.com>
> >Subject: RE: Europa-List: Tailplane flutter
> >Date: Mon, 25 Jun 2007 11:29:20 +0100
> >
> ><nigel_graham@btconnect.com>
> >
> >Hi Graham,
> >
> >FYI - I am working with Ian Rickard at the moment to document exactly
>what
> >I
> >did and present this to the PFA.
> >
> >To enlighten those of you not familiar with this mod:
> >A long time ago I identified the inherent shortfall with the TP14 method
>of
> >securing the drive arms to the torque tube. Merely replacing these pins
> >with
> >oversized pins would not in my opinion, cure the problem - only delay the
> >next re-occurrence once play developed.
> >
> >I developed a simple arrangement (KISS technology) that positively clamps
> >the drive arms (TP9 and TP12) onto the torque tube by replacing all four
> >TP14 pins with 1/4" x 2.125" AN bolts.
> >To support the torque tube and prevent it distorting, 15mm wide
> >cross-drilled discs are inserted into TP4 at each of the four stations.
> >To spread the clamping load over a larger surface, "saddle blocks"
> >(profiled
> >to mate with the OD of TP9 and TP12) are fitted under the bolt head and
> >castellated nut.
> >
> >The beauty of clamping is that it introduces a torque damper into the
>drive
> >system - eliminating the shock "chattering" that wears the standard TP14
> >pins and elongates the holes - and it can be retrofitted to tubes with
>worn
> >holes.
> >
> >Nigel (The other one) Graham
> >
> >
> >-----Original Message-----
> >From: owner-europa-list-server@matronics.com
> >[mailto:owner-europa-list-server@matronics.com]On Behalf Of Graham
> >Singleton
> >Sent: 25 June 2007 00:25
> >To: europa-list@matronics.com
> >Subject: Re: Europa-List: Tailplane flutter
> >
> >
> ><grahamsingleton@btinternet.com>
> >
> >Carl
> >The torque tube is chrome plated 4130 I believe, stainless isn't strong
> >enough.
> >You may have spotted the weakest link in the chain, if the TP9 & 12 had
> >more bearing area the slop problem might go away. Wouldn't be much
> >weight penalty either.
> >OTH clamp bolting as Nigel Graham did years ago might be the best answer.
> >Graham
> >
> >
> >
> >
> >
>
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