Re: Rudders and brakes (breaks)

[mhadley1@juno.com]

On Fri, 1 May 1998 11:16:51 -0700 "Al Gietzen" <alventures@email.msn.com>
writes:
>
>Shouldn't we be alarmed that rudder cable breaks have been occurring in
>Velocitys for years, and when still secure them the same way.
>
>Doesn't the fact that needing full rudder when landing in turbulence 
>or crosswind could also result in a firmly applied brake and a resultant

>broken gear leg mean that a design change is needed?
>
>Alarmed,
>Al Gietzen  RGE
>
Dear Al,

While it is true "landing in turbulence or crosswind could result in a
firmly applied brake and a resultant broken gear leg" does NOT in and of
itself imply there is a poor design in they system. You can easily rip
the gear off a Cessna in a turbulent or excessive crosswind landing. 

As far as the "firmly applied brake" goes, that could be attributed to
lack of experience (feel) knowing where the rudder stops and the brake
starts...or even panic. I can only say that N81VA gets beat up, bounced,
and landed worse on a more regular basis than any one of your aircraft is
going to get exposed to. After 12 years and 2000+ hours, the gear is
still on and in tack. Nothing like real time field testing! 

As far as the rudder horn to cable connection, this situation could use
some scrutiny. The cable begins to break strands when  the rudder is
moving in and out without the pedal being depressed. This occurs whenever
there are gusty winds on the ramp and there is no rudder locks in place.
Pressing the pedals creates enough tension on the line so that the cable
/ nico press joint stays in-line. When the rudder is deflected without
tension on the cable, it tries to push the cable back into the nylaflow,
which is kind of like pushing a rope up a hill, and it invariably flexes
the cable right at the nico press. A couple of hundred, probably
thousands of time of this, and the strands begin to break.

Al, it's almost 2AM...and I have a brainstorm, maybe a brain fart....  A
simple slip joint at the rudder horn!   Manufacture a fork on the end of
the horn. Drill a 3/32" hole in the center on the shank of a 1/4" clevis
pin, being sure to debur and radius the edges of the drilled hole.
Install the 1/4" clevis pin through some oilyte bushings pressed into the
top and bottom 'fork',  liberally lubricating and placing a thin washer
under the head of the clevis pin and a thin washer and cotter pin at the
bottom of the clevis pin. Run the 1/16" cable through the hole in the
shank, double back through a nico press (or ball) and  attach the nico
press or ball firmly.

When we apply pedal, the nico press (or ball) is seated against the
clevis pin and pulls the horn in. If the rudder is moved without pedal
input, the cable is free to slide through the hole while the pivoting
action of the pin reduces the amount of flex the cable sees at any
localized point.    Is it late? Or did I just have an idea?

Now then, before anybody jumps off the dock, what kind of wear and tear
are we going to get on the cable while it is sliding back and forth in
the clevis pin? Or vice versa? (Stainless steel cable vs. carbon steel
clevis pin.) What happens if the clevis binds or freezes and does not
rotate? I can't see where or how we would have to worry about the cable
breaking at the nico press or ball end, though. 

Talk to me folks...does any body want to give this a show?

Sleepless in Palm Bay

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