Wing Installation - Part 4

This blog covers the installation of wing aileron and push rods.

Overview
The ailerons on the Tucano are operated by a series 7/8''  OD aluminium push-rods mounted on a series of rockers arms fixed to the rear spar with all holes and nut-plates factory installed.

Push-rods
The push-rods were all fabricated using the factory supplied tube, inserts and rod ends.
At installation of the rockers and aileron bell cranks had their location marked onto the face of the spar while in the neutral position, 60 mm was deduced from the center distance allowing the rod end and bush to be installed at the factory preferred starting length.

Note: The length of 30 mm is measured from the rod end center to the rear of the flange of the insert

The factory inserts were all little tight when trial fitted into the tube so it was decided to turn a whisker of metal off in the lathe using a  AN4 bolt as a mandrel to hold the insert for machining.

Turning inserts to create slip fit in tube

With the inserts prepared the tubes were cut to length, inserts riveted using four [4]  x 4 mm x 8 pop rivets. There is a recess machined in the rear of the insert  which are drilled into placing the center-line of the rivet center-line 2 mm from that point.

Note: Before assembly the inserts were primed as was the inside of the face of the tube

With the tubes fully primed a AN4 shear nut was installed in reverse onto the rod end and adjusted to place the rod end center 30 mm from the rear of the insets flange.

Note: To allow the nut to be used it was first installed in the correct direction, removed, rotated and reinstalled as described

Ailerons
The ailerons with this kit were supplied finished except for the front fairing. To install the fairing this had to be de-riveted and trimmed for installation. The rivets were removed and the edges trimmed using the factory supplied cutting guide and the Ofla knife. After trimming the edge was trimmed and sanded smooth with well watered 400 grit wet / dry paper.

Preparing aileron skins
Trimming aileron skin in place

The aluminium used is very thin, soft and will buckle or tear with little or no effort. The plans call for 3/32'' rivets but this kit had been tacked with 1/8'' rivets so it was decided to use these to allow the original rivets to be matched.

After trimming the fairing edge to overlap the skin was looking a little untidy and it was not all my fault so as per the elevator it was decided to install the edge under the structural skin.

To ensure a watertight seal it was decided this time to use a silicon bead under the main skin to ensure no water can enter in service. It was decided to use Selleys Solar Flex black silicon which is paintable, slow drying allowing time to clean up.

The structural edge had to be trimmed in position which was accomplished with the Ofla knife , protective strips and a file with a safety edge. With the edges ready the fairing was inserted and a handful of clecos installed. 

With the parts ready a tape edge was run along to collect the excess that will squeeze out. The temporary clecos were removed and a bead of silicon added using a handgun and then the edge was fully clecoed and finally the edge worked with the thumb to assist in squeezing out excess silicon. With the edge ready every second cleco was removed and riveted the remainder removed and riveted. Finally tape was removed and the edge cleaned up with thinners and lots of disposable hand towels.

The final task was to rivet the fairing and this is when problems occurred. All original holes were clecoed with 1/8'' clecos then the remainder fixed with 3/32'' clecos as required. At this point is was noted that the alignment was not good at a number of the holes.

"Let a sleeping dogs lie, it might 
not end up very pretty"

All the 1/8 holes were riveted and the plan was to enlarged all the holes with a #30 drill. Being a half a hole out is just a big problem and I managed to tear two of the holes as this material has no stiffness and the hole steered the drilling. 

Not happy but it is not fixable and as this is a fairing but it reflects on the person drilling the holes and the torn holes were riveted using a large head rivets as a cover up. To attempt to make this perfect would only create a bigger mess.

Assembly
With the components ready,  rockers, doubler plates were installed to the factory plans with the push rods. After all adjustments were completed the hinges were fitted onto the ailerons using AN3 bolts fitted into nut-plates.

The ailerons were installed remembering to insert washers between the face of the bearings and ailerons brackets, next the coupling, rod end bearings were assembled connecting the ailerons to the push-rods. The system was adjusted by eye into alignment, this will have to be finally trimmed later through the inspection hatches. 


A foul with the outboard hinge on the fairing had to be rectified and was modifyed to match the opening on the opposite side.

Aerilon issues

Note: The aileron mounting brackets were aligned with the flap installation and riveted to the main spar with pop rivets to fix their location with another small problem with the middle rocker rivet nut requiring modification [wrong rivet nut installed at factory]

Comment
The aileron fairing was a disappointment as the holes were poorly matched drilled and need extreme care during the whole installation process which was not recognised by the builder early enough.