Hi! Mark./Fred
MARK. I reckon you've made a good observation. Let's face it there is a
substantial load needed on the control stick at about 18" lever to activate
the mass balance weight without the tailplanes fitted, so the weight and
leverage has to go somewhere and the pins /TP12's are at a very small lever
arm so the weight must be quite high.. the elongation of the TP12 holes is
definitely wear not a tear and the amount is so small, it's just the ratio
multiplication to the trailing edge that makes for the measurement there
substantial. What is your perception of the published maximum opposing
travel between both trailing edges?
Andy Draper would have me say he is "revisiting the problem and calculations
are being done for 3/8" oversize pins to replace the original pins."
In the meantime I'm progressing with my clamp because with ZERO movement
there'll be NO wear EVER in that location OR on the TP9. However I have
spent 4 hours with mole grips pulling the one size oversize pins out (that's
how tight they were reamed!) since I had to dismantle it all to shorten the
TP10 Nylon bushes for my clamp to have more "land" of the TP12's to be
gripped. Incidentally
I also decided that since I now have it all apart I'm upsizing to 5/16"ths
as well. BUT I do expect this will be the LAST time it needs to come apart.
No out of balance start up on the 3300 Jabiru, Fred. and not that much grass
field work but probably twice as many landings (bounces!) as the records
show!!!!!
FRED, it hasn't been suggested to apply the loctite to the pins but the TP12
drive plate/bushes to the torque tube TP4, that's why I'm suggesting
problems with heat to release it again could have an effect on the Redux
used to position the Bronze bearings. Only 153 hours on G-PTAG yet. How many
hours on yours?
Regards
Bob Harrison G-PTAG
-----Original Message-----
From: owner-europa@post.aviators.net
europa-builder@ntlworld.com
Subject: Re: Tailplanes
----- Original Message -----
From: "Fred Fillinger" <fillinger@ameritech.net>
Subject: Re: Tailplanes
> Bob Harrison wrote:
> >
> > Hi! Barry.
> > I also tried the ring of loctite on the outside (carefully because you
will
> > have a "bad hair day" if it gets in the main bush,) and only one side
> > ,however keep it/them checked because it could still come loose without
the
> > bulb, mine did ,been there done that...... also remember that the
phosphor
> > bronze bush is a very effecient heat conductor through to the Redux
holding
> > them in place.
> > So ever slowly the numbers of people that have this problem is creeping
up,
> > I was begining to think it applied to only a few!
> >
>
> Is it more than a few? The original inquiry, and my response, were
> from builders with zero hours yet, and at least mine are fine!
>
> I wonder, though, if both pins have been Loctited, how does one
> introduce heat through the torque tube on the first tailplane to be
> removed?
>
> Is there a consensus as to the cause of eventual looseness?
> Rotational force against the pin in cruise should be zero, without any
> pressure on the stick. Maybe some turbulent air and helical prop wash
> on the stabs, but is that enough to distort the steel to make the hole
> larger? Aerobatics then?
Is this true when you consider the mass balance weight? The fact that the
stick doesn't need anyone holding it and the plane stays level, suggests to
me that there must be a force on the pin to counter balance the mass balance
weight. This would then make me think that any slight movement on the
tailplane (due to the air), would put quite a lot of force on the pin,
especially if flutter isn't induced.
Cheers,
Mark.
________________________________
Mark Jackson - 07050 645590
europa-builder@ntlworld.com
http://harley.pcl.ox.ac.uk/~mark/Europa
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