Bits and Pieces No 1

The time had arrived to complete an number of tasks to allow the others to proceed and it required a full weekend to bring them completion.

Tail Wiring

The cores were installed in 10 mm loom tube to provide power for the tail light and red strobe. The cables bundles are fixed to the frame using 10 mm nylon saddle clamps and 3 mm large head pop rivets.

Cable runs at rear off fuselage

In reading the notes for the rear tail light an additional core to allow a strobe function was missed and it was decided to add this feature. This required two [2] 20 gauge core to be added and the existing 18 gauge core to be removed, this simple task took 3 solid hours - why?

The cable was installed in the fuselage, fixed and all work had to be preformed at the rear from a floor trolley and from bulkhead to bulkhead on the fuselage side. It only reinforces my opinion that wiring is not a job to be done when the construction ends for a whole heap of reasons but the best is the bulk time it adds to the task.

Cable runs starboard side longeron

The loom tubes were installed in the starboard upper longeron, these were secured with self adhesive pads and cable ties. To ensure that all was to be safe when the cover is fitted and all access lost, foam pads were fitted and secured with cable ties [removed when cover was installed]. 

The pads apply light pressure to the loom tubes holding them in their correct location when the skin is installed.

Fourth loom tube

Three tubes filled the available  area in the longeron so the cables to the tail was added as a internal fourth run fixed to the inside of the fuselage. 

The tube was fixed with 10 mm nylon clamps fixed by M3 x 9.6 mm pop rivets and washers to ensure the pop rivet fully expanded.

Two plug's were installed at the rear to allow the fin and elevators to be electrically disconnected for painting or heavy maintenance.

Trial Assembly of starboard covers [note inlet for cockpit air]

With the wiring complete and side covers clecoed on the next task was to install the roll bar. This had been previously trial fitted and upper mounting holes drilled in the longeron. There were no issues found with the lower factory mounting holes in the fuselage and were fixed with AN3-6A bolts with area washers installed on the inside face of the upper longeron to provide increased rip out strength. 

A tapered packer was required at the port side between the upper roll bar mount and top longeron to fill a gap between the upper mount on the roll bar and longeron.

Roll bar installed

With the roll bar installed the side panels can be fixed to the fuselage using the factory drilled holes. The bolt heads were located to the inside to allow ongoing inspection.

Port Side Roll Bar attachment
Information on this co-pilot air system - click here

Rear hinge

Canopy Hinges
Additional rivets were added to both the front and rear hinges as noted on photos supplied of the current factory aircraft. The location of the initial hole was covered in a previous blog - Part 2.

A packer was installed to match the skin mounting angle to prevent distortion of the longeron flange.  

Two new 4 mm holes were added and secured with aluminium rivets.

Front hinge

Note: Drilling the stainless steel bracket requiring WD40 and a [sharp] 2 mm pilot drill then enlarged to 3.5 then 4 mm. All holes drilled using a battery drill to avoid burning the drill tip.

The front hinge was secured using the single hole drilled at installation [Click link above]

A stainless steel 4 mm pop rivet was used to provide improved rip out resistance over an aluminium rivet.

Packers

Packers
Packers were installed between the side skins and the firewall to improve the profile of the assembly when riveted. 

This was done on both sides with the port requiring a larger packer set

Rudder Pedals - Part 3

Set out second bearing location

The set-out was squared from the inside face of the longeron, with the location of the first pedal assembly determined as outline in Part 2.

The first set of rear pedals were assembled and fixed to the connecting rod. The pedal was positioned in a vertical position while ensuring the front pedal were in their correct position. Once the correct location was determined the location of each mounting point was marked and M5 riv-nuts installed [refer note below]

Rear Pedals set out

The position of the first pedal was transferred to the opposite side using the longeron as the set-out again and the same technique applied to locate the other axis.

Insert - refer builder note below

Both pedals were fully assembled and installed with M6 X 75 Unbrako cap head screws to secure the bearing blocks. All bolt threads were cut to project 2 - 3 thread from the end of the -nut to save weight. 

Modifications - refer disclaimer
The rod end mounts for the rear pedals were trimmed 20 mm to open up clearance to the side of the seats - this was a personal decision. 

Builder Notes
Accurate installation of the riv-nuts is critical as the bearing blocks offer no clearance. Each hole was drilled 5 mm then bolted. The next hole is drilled at the opposite block, bolted and then repeated at each location, then all the bolts were removed and riv-nuts installed. This was important as as each bolt is installed any clearance is lost.

A error was made and that hole had to be drilled oversize, plated, drilled a riv-nut installed then the cavity was filled with Loctite aluminium epoxy and dressed smooth

The other item is that the bearing blocks should be kept as matched sets, this builder failed to do this and dose know better. It can be sorted out BUT creates a Chinese puzzle with decreasing options as the parts are used up = lost time.

Factory procedure - recommended

Rudder Cables - Part 1

As part of the installation you have to manufacture the rudder cables for the aircraft. This task can be undertaken in an approved workshop or the builder manufacture them. This builder chose the latter but there are a couple of items that had to be purchased to undertake this task. 

To understand the skills required please review the E.A.A. Video line below or speak to your project supervisor.

A Economy Nico Press Swaging Tool No 2 Swage shown below and a go-no-go gauge were selected.

Nico Press Swaging Tool

The kit for the rudder includes all the components to manufacture the cables to suit the aircraft. The pulleys and bushes were installed in Part 1 with the cable to be threaded from the copilot pedals to the exit at the rear fin post. 

Cable kit

This builder cut supplied cable in half, leaving the tape in position until swagging was undertaken . 

Cable End Assembly

Note: 1/8'' cable requires 2 fittings at each termination with each swage to be crimped three [3] times.

See EAA video's below

Rudder Attachment

Shackle

Brass bushes are supplied to be assembled through the thimble then secured to the rudder horn with a AN3 drilled bolt, castellated nut and split pin. 

Modification: MS200-15F4 shackle's are to be fitted with an AN3 bolt, castellated nut and split pin.

     Cutting Cables 

   Swaging Cables

   Fitting Split Pins

Trim Tab - Part 5

The tab clevis attachment requires a stiffener - a three [3] sided tray was folded with two sides trimmed to match the rib profile, The front edge was match drilled using the front edge of the tab. Two [2] angles were folded to tie the side webs to the front of the tab skin. All rivets used on the lower skin were 1/8'' counter sunk to allow the faring not to foul in operation on a dome rivet.

  

Tab clevis reinforcing plate

Stiffener was cut from the scrap material from the trim tab folding. 

The cover plate was slotted to allow the full operation of the MAC trim motor. It had to be wide enough to allow the clevis to clear the cover.

Trim motor cover

The final assembly with the faring cover for the tab and motor fitted. The cover for the motor was the prototype for the rear light of the rudder. This was machined from a 3D model in China but was not suitable for the task but has found a new home.

The inboard rib had a 1/2'' hole drilled on the same center as one of the lighting holes in the attachment plate for the shaft that connects both elevators. The loom for the trim motor exits through this opening to connect with a six [6] pin plug located under the rudder fin. Access  will be gained by removing the fuselage fairing. The hinge pivot was secured using a scrap piece of hinge pop riveted to the rib.

The threaded rod has a crank to allow connection to the tab clevis attachment to allow full stroke of the motor without fouling the tab spar.

Inboard rib details

Final task is to attached the tab clevis and test the assembly and at this time no problems are foreseen - famous last words ! 

Trim Tab - Part 4

The next task is to fabricate the braces for the stiffener installed in Part 5. A MAC trim is capable of a 40 lbs of thrust and the thrust is transferred to the rear spar via the ribs as per the factory installation.

A motor mount Z profile was folded from 0.025'' 2024-T3 aluminum - 60 mm wide with 10 mm flanges. Two lighting holes were created because a suitable flaring tool was on hand.

Z frame trim mount

Two angle mounts were fabricated and fitted at each end after a series of trial fittings ensuring that the second rib was maintained in its correct location relative to the mounting holes in the skin. Brackets were fixed with 3 x 1/8'' pop rivets to the face of the Z as shown above.

#3 Rib mount 

The cover plate was now slotted to accept the trim motor link.

Trail fit of MAC drive

The motor center line was located on the face of the Z and the first two mounting holes were marked with a felt pen - both holes were drilled and the motor mounted with cleco's then refitted, position checked and the rear holes marked.

On this install the rear two holes were moved up to provide improved access from the available opening.


All holes were fitted with 3 mm riv-nut's at the motors mounting points then refitted to determine the best angle to suit the available opening. 

The #3 rib the center hole was drilled, clecoed and repeated at the other side using one of the mounting holes for the new rib foot. Once the most suitable angle was determined using the trim motor the other holes were drilled and pop riveted.

Mounting Z Bracket at #3 rib

The motor was re-installed using four [4] M3 x 12 pan head screws then the stainless steel clevis attachment was fitted to the tab with 1/8'' pop rivets.

Trim Tab - Hitting a Wall

OH NO.!

At this point the builder stood back to admire his work and OMG the trailing edge of the tab was clearly not in line with the elevator skin. 

A loud crash of a builder hitting the wall was to be heard. After contacting the factory a series of photos's were received for guidance. 

I had swapped the inboard and the adjacent rib with the other frame's due to a mix up in the skin labeling as both had been cut and it was felt that this would allow me to proceed with both elevators. In trying to fix the problem by swapping the affected ribs it may have had unintended  consequences during the process of assembly .

Note: The frames are symmetrical so there is NO port or starboard until the tab is cut and positioned, its the relationship between the skin and frame that counts at assembly.

What to do

When you create a problem like this, how do you fix it is the $64 question. 

After a examination of the frame it was decided to remove the #2 rib, behold most of the misalignment was released. The next decision was to re-manufacture the trim tab spar as it was only fixed with clecos and it would allow me to start with a clean slate.

A fixed reference was created using a 1.5 meter length of 25 x 25 x 1.5 aluminium angle clamped to the elevator for all of the assembly tasks. One of the big differences between the factory and my procedure is the availability of jigs. The frame is a moving feast for most of the assembly period and this may have amplified any errors made.

A aluminium packer was installed at the underside of the outboard rib [#1] to improved fit to the new spar [see photo insert above]. The new spars were folded from 0.030'' aluminium [what was available] with the overall width matching the first full rib #3 and a second spar was folded with the overall width reduce 3 mm to clear the inside face of the first. 

First spar begin inserted - final assembly see insert

The procedure followed the previous blog on the original installation except that I started with the top spar to make alignment a little easier.

The front spar was cleoed at two places to allow a re-position if required. Next the lower spar was fitted to the underside of the first spar and cleoced at two places.

The spars were refitted and adjusted until the angle between the spar faces and the skins were are in alignment. The final tasks was to fix the two using 5/32 rivets pitched at 30 mm using the jig supplied to mark the spar.

Second Spar added with the first fixing

Riveting Tab Spar

The second rib had its mounting removed and was installed as a floating rib attached to the skin only. 

As this had created most of the previous error it was felt that it should not  exert force during re-assembly.

Tab Assembly

The original tab assembly was refitted and aligned using the angle as a guide and once satisfied the a cleco was installed at the inside rib. As the hinge was already drilled, alignment of the next hole required the used of a tab clecoed to the rear spar that allowed the hinge to be opened up, positioned and a hole match drilled. The tab was refitted and the whole alignment checked again - once satisfied two 5/32 rivets were installed.

Checking alignment of tab

The whole assembly was carefully checked and once satisfied the top spar's were match drilled from the skin's and clecoed to ensure that no unwanted movement occurred and then the trim tab hinge was matched drilled and pop riveted.

Once fully satisfied the top skin was pop riveted to the tab spar and the ribs except at the last rib and main spar to allow the D nose to be fitted later. The reason was two fold, one to make the final work to install the tab motor easier and secondly to CLAMP the frame up with the rivets

This time I was glad to see the finished product.