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
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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