Rudder Cables - Part 3

This blog cover the installation/alignment of the rudder and associated cables

Turnbuckle

It was decided to use  AN155S Barrels / AN161 22S - AN161 22L  forks matching the overall length of the factory supplied S/S turnbuckles.

Push Rods
The original factory front ball joints supplied for the nose leg were found not durable in service and were replaced with plain rod end bearings . A 5 mm thick tube spacer was required to allow the rod end to clear the front attachment at full deflection. 

Note: The spacer was required to duplicate the original ball joint geometry and are now supplied with the kit

Stainless steel bolts were manufactured to ensure that only shank bare on all rod ends when installed with an  area washer fitted to prevent the ball joint escaping in the event of complete mechanical failure.

System Adjustment
The rudder fin was locked into its neutral position by using two aluminum channels fixed to the stab with automotive trim tape and foam wedges to lock it position.

The co-pilot pedals were locked in position with lengths of 16 mm curtain rod inserted into the pedals mounting allowing the cable to be adjusted and locking the rudder into its correct position. With the initial adjustment completed and the cables having a light tension, both aluminium channels were removed.

Note: A series of holes were drilled to achieve the correct location of the pedals in combination with packers at the end of the rod, wedged against the bulkhead. 

Sharpened bolts were used for quick install and release of the assembly during setup.

Pedal locks
White tube is 16 mm curtain rod

The pilot's pedals are fixed by the connecting rods relative to the copilots pedals, checking revealed that the previous work to set the centers was correct and both pedals are in a near vertical position with the cranks adjusted to the vertical position.

To align the nose gear a length 1'' x 1/4'' aluminum bar was mounted parallel to the nose wheel attachment and adjusted until parallel to the main spar using a measuring tape [not fun one up]. 

 

Nose wheel alignment gauge

The connecting rods that had been fabricated in house allowed only a few millimeters of adjustment so it was decided to remove both rods - shorten them by 12 mm, weld, strip, paint, primed and then repainted.

The cranks position were adjusted with the nose wheel location set as described above.

Pedal-Crank reference
marked for ease of
reassembly

I had chosen to drill the crank/pedals at this point and drilling in situ had disaster written all over it. 

With the the pedals and cranks aligned the position of the vertical bolt hole was marked through the crank onto the pedal shaft with a scriber. 

The pedals were removed, drilled and after dressing, Loctite no-sieze was applied and the pedals reassembled.

Both connecting rods were attached, bolts torqued as required then lock-wired.

Rudder wiggled
by the pedals

Note: Thread lock had been applied to the rod end retaining bolts on the previous installation, not a good idea as it penetrated the rod end and created a lot of extra time removing those bolts.

System movement was checked for free movement by hand - all seemed OK.

The cable will be tensioned once I can source a cable tension meter then lockwired to the video before closing the skin. Most likely the nose wheel will require a final tweak before testing.

Comment
Preferred aircraft graded turnbuckles.

The system is functionally complete requiring only final adjustments and lockwiring of turnbuckle