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
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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