Wiring Fuselage - Part 2

Starboard cable runs

Exit to flap controller and hydraulic pump

All wiring to operate the flaps, hydraulic pump, trim interface have been built into the starboard upper longeron. 

Refer Wiring Fuselage - Part 1.

The loom tube has proven to be the neatest and quickest way to install wire bundles that I have tried.

The tube that carrying the power for the flap drive has had pull wire installed if there is a need add an extra core's once the skins are on. All other tubes are full.

All loom tubes are secured to the face of the longeron using self adhesive pads and cable ties pitched at approx. 200 mm. .

The number of tubes was limited to three [3] due to the a pinch point located at the change of direction in the longeron.

All exit points located on the lower flange cut back to the overall width of the top flange. 

After dressing the edges are covered with rubber channel fixed with contact.

Exit to trim interface

Cable exit at firewall

Cockpit Painting - Part 2

What dose the picture at the side say - it has to be painted to proceed.

Rudder Pedal

As the only upholstery in a Tucano is paint therefore it's important that the painting be undertaken at the correct point to allow assembly to proceed. If left to late it requires masking and removal of installed hardware so with the side panels finished and work piling up it was decided that it's time.

The real choice was the color. My initial thoughts were to use Wayttyl SLS primer in the pale grey coated with acrylic gloss. This in fact was the combination that was used on the sticks with good results but the RS Warbird cockpit with RAF camouflage scheme just kept screaming "pick me!" and I had to listen.

The die was cast.

RS Warbirds custom cockpit

A number products were tried but the only color that was close was from Wattyl in a Epoxy Single Pack Enamel. It was decided "Machinery Grey" was the correct color and four [4] tins were purchased. 

All the cockpit walls were already in the etch primer it was expected to cover well. The primer was lightly rubbed with fine sanding pads, scouring pads, wiped with wax & grease remover then dried with a clean cloth. The spray paint was placed in the sun for about an hour to warm up, then the painting began at the firewall and stopped at the baggage compartment bulkhead. A drop sheet was applied over the top of the cockpit and the area allowed to dry until tack free, about eight [8] hours. Once the cover was removed a smooth high gloss was revealed. This paint requires 24 hours or longer to dry and in any thicker areas it may take a week or more.

With the paint dry, assembly of the rudder pedals and other hardware can now proceed. The downside is all new brackets, panels have to be fully painted before installation with the associated drying time. 

Panel
Grey was quite a rebel color when used 20 years ago so is black the new grey?  With the a "Spitano" theme black fit's, so a satin black finish for the panel and top side cockpit frame is appropriate.

Fuselage Firewall - Part 2

Flying Legend has informed me that from Jan 2015 all Tucano's will have a 0.015'' stainless steel firewall fitted, so the real purpose of this blog is to document the work for the approval requirement's and to show you how much fun you miss out on.

Wheel Well
The wheel well was fabricated from 0.5 mm stainless steel sheet to allow it to match the strength of the aluminium but it proved to be a bit of overkill as 0.015'' will do the job. The new profile was folded from 316 annealed stainless steel to just fit inside the existing wheel well cover. This was done to allow all the pre-drilled holes to be added to the new cover with the highest level of accuracy.

Once the fit was checked it was clecoed into position and a new back fabricated from 0.015'' stainless steel grade 304. The 316 annealed stainless was easier to work with but that was not available. The rear cover was matched drilled from the new well cover and clecoed into position with the final job to pop rivet all the panels using 1/8'' stainless steel rivets x 6.4 mm long.

Firewall
The easiest way to cover the existing panels was to duplicate the existing aluminium panel in 0.015''stainless steel. The issue was that the material sourced was not large enough so it was decided to manufacture the lower corners as separate pieces. The profiles were traced onto the blank sheet and cut using a combination of a nibbler and snips. The edges were then dressed using a 300 mm disc sander to final profile.

The upper panel had the original holes for pop rivets added and these were duplicated at the bottom edge using a strip cut from the firewall containing the original pop rivet holes, when complete they were clecoed to the firewall. 

The lower panels were cut next with an additional 20 mm added to slide under the upper sheet and secured to the new row of rivet holes.

The final task was to fold angles to cover the junction with the well and fires wall. Once completed a bead of high temperature silicon was added to cover up a couple of small holes and another dab added at the corners of the wheel well.

Trial Assembly 

Repairs
Stainless steel is razor sharp when cut so the various blood trails were moped up and fresh strips added to cover the various body wounds. The builder then sterilized himself with a couple of high alcohol beers - very cold beers.

Rudder Pedals - Part 1

After the floor plates are installed the next task is to fit the rudder pedals. 

The nylon blocks and fixing screw's were disassembled allowing the working face's of the pedals to be polished back to bare steel, sharp edges on the nylon blocks are chamfered lightly with a scraper.

The pedals paintwork is now touched up and coated with gloss acrylic as discussed in the article on painting. 

Connecting Rods
The factory supplied connecting rods are a stainless steel 8 mm o.d. rod with welded adapters to accept the M6 rod ends. Install the rod ends with M6 jam nut's. 

Install the connecting through the slots in the bulkheads near the floor, fit the rod ends and adjust to their initial positions ensuring that both rod end assembly's have the same center to center distance.

• What is the minimum thread engagement required to support the advertised load ratings in the Aurora Bearing Company catalog?
• The minimum thread engagement is 1.5 times the major thread diameter unless otherwise stated.

Pilots Pedals
Installed a temporary hanger manufactured from a piece of scrap aluminium fixed to the frame and the pedal board with clecos. This was leveled to the top side of the wheel well using a digital protractor. This was important to locate the pedal assembly accurately.

With the connecting rod laying in base of the slot's in bulkhead #2 & #3 to center it, lined up the mating mounting faces of the rod end and pedals. With the pedal positioned on the center of the wheel wheel opening - marked the location of the first hole with a transfer punch, removed the pedal assembly then drilled all the hole to 5 mm. [refer note below]

Nylock 6 mm nuts and washers are supplied fix the pedals to the floor. All M6 screws have Loctite Thread Lock applied at final assembly along along with a light application of grease onto the working faces of the pedals to prevent corrosion and improve operation.

Check for smooth operation - shim bearing gap if required.

Shimming
To ensure smooth operation a shim of 0.010 - 0.012'' may be required to reduce the clamping pressure of the nylon bearing.

Note: The first holes was drilled and a bolt inserted and tightened, marked the next hole in the opposite block on the diagonal, removed and drilled then marked the last two holes and drilled. It is critical that this be done as accurately as possible as there is only a small clearance in the bearing blocks mountings. 

Pedal in final position - squared from side off wheel well

Modifications: Nylon bearings are fixed with M5 medium-reach riv-nuts to allow removal of the pedal bearings for servicing and adjustment of clearances once the belly skins are installed.

Custom bolts were manufactured using M6 X 45 Unbrako screws. The bolts where hand threaded to provide the required amount of plain shaft to suit each application. Threads were trimmed to correct length and polished using a plastic buff on a bench grinder to remove all sharp edges. 

These bolts replaced any fully threaded bolts used in the pedal assembly's.

Nylock nuts or Loctite thread lock was used to secure all items.

Factory Aircraft - the pilots floor plates have a folding
added to raise the heal plates height