Bits & Pieces - No 6

This blog covers the small tasks to finish the elevator installation

Rudder / Elevator Stab Fairing
After the disaster of nicking the spar plus the well documented repair it was decided this was to be a slow and careful installation. 

The first task was to mark out the locations of the ribs and spar to ensure that the drilling advanced the process not create more unproductive work.

Marking out rib locations before drilling

The top holes on the port side did not create any issues so there location was now carefully reproduced on the starboard side - then checked.

All holes are fitted with M3 rivet nuts and the fairing drilled 4 mm to provide additional clearance for ease of fitting. 

All unused holes were filled with spot putty, sanded and primed.

Rivets to fix the fairing allowing quick removal

On the underside only the front and rear fixing were installed and obtained a relatively neat fit with the lower stab.

Comment
Took another day to tidy up all these small loose ends in this area but it is now ready for paint preparation.  Should have done this the first time and would have avoided a lot of unnecessary pain.

Main Leg Lubrication

This blog cover the installation of greasing points into the main undercarriage leg

Overview
This builder decided to add greasing points to all high load pivots of the undercarriage for lubrication as required at bi-annuals /100 hourly.

Trailing Links

Bolt held in block, trimmed
then machined to length

All bolts were renewed to provide 100% bearing on links this required the purchase of a set of M6 x 90 mm Unbrako S/S bolts and remixing the factory supplied bolts. 

At installation M6 S/S spring washers were installed under each bolt head, this washer locks the bolt and arm together ensuring that all rotation occurs in the major attachment point located on the main gear leg. 

All bolts shanks were greased before installation.

Note: The changing of the bolts ensured that thread was not located in the working portion of components - shank support - thread retain. 

The center pivot blot was replaced with a M6 hex head to provide clearance to grease bolt on the main pivot mount. This was created by an unforeseen issue with clearance to the grease nipple on the main when the gear closes. [see note below]

Main Pivots
The boss face was drilled 3 mm through then drilled, tapped M5 to fit the grease nipple after facing the boss depth to 15.5 mm. To contain the grease at the rear a 1.5 mm cover was cut from 2024 aluminium sheet using a hole saw with the pilot hole filled using a 5 mm pop rivet and washer. 

Finally the cover was sealed with Permertex sealant, fixed onto the boss face using four [4] x M3 screws fitted into blind tapped holes. 

Note: After breaking a tap it was found 3:1 oil worked best as a tapping lubricant in this aluminium. A ratchet T wrench was purchased and proved to be perfect for this task.

Trial installation main pivots

The pivot arm was next filled using two [2] plugs of 25 mm thick builders foam foam cut with a ceramic hole saw. These plugs were pushed into the shaft and sealed with Permertex high temperature silicone.

Main Pivot Seal

Note: The hole saw was one in a bulk lot purchased to cut the holes for the seat belts with one perfect to produce the plugs. Plugs were fitted to prevent filling the arm with grease.

Hydraulic Cylinder Pivot
The rear of the cylinder mount was tapped M5 and a nipple fitted with a 12 mm hole drilled through the rib for access to the nipple. This position is not easy to access and will require a re-grease to be undertaken from the inside of the fuselage.

Note: Note sure about the access until the wings are mated

Drag Links

1/8'' Zerk drive nipple

Both drag link bolts are converted into grease bolts by drilling a 2 mm hole from the head side to the shank center with the head side redrilled to 1/8'' to accept the drive nipples, then finally a 1.5 mm hole was drilled to the pick up the end of the 2 mm hole and chamfered using a drill.

The M6 bolt hex was filled with silver solder and machined and drilled as outlined above with a nipple fitted. The disadvantage being it has to be tightened by clamping the head.

Cylinder is fitted with a stop collar to fix the stop point
stopping the gear just short of the top skin by about 5 mm

Stop Collar

The main M8 pivot bolt was drilled again as outlined above but it was found to foul the leg necessitating the machining of the head to a overall depth of 5 mm and the nipple reinstalled. The nipple overall height was reduced by 1 mm to improve overall clearance.

As noted above the center bolt in the trailing link group passed the nipple resulting in the cap head bolt beign replaced with a Grade 8.8 hex bolt - Murphy's Law in full application.

Another step forward

Comment
Doing it again the 1/16'' cover would be machined from 60 mm round and fitted with counter-sunk screws as the M5 rivet head made reinstallation tight.

All points where pressure lubricated and as expected more grease can be applied under pressure than by hand.

The limit switches will be covered in detail in a separate blog 

Bits & Pieces - No 5

This blog covers most of the last small tasks related to the rudder at final assembly.


Rudder Fairing

Tucano Tail

While only a just a little untidy it qualified for a upgrade and it's not a lot of work. 

A strip of 0.020" 2024-T3 sheet was cut, lower rivets removed, strip clecoed into position and rudder movement checked OK.

Once satisfied it was installed and riveted.

Note: The fairing bell mouthed slightly as it 
is really a developed shape and mine was straight but the result was acceptable.

Fairing upgrade

D Shackle

Rudder D Shackles
The factory supplied connection was replaced with a D shackles fixed with a clevis pin and castellated nut. 

This was changed as the original connection did not create a double shear connection but has now been upgraded for the aerobatic kits.




Rudder Adjustment
The top bearing is adjustable laterally to align the rudder mass balance and stab and is has slotted mounts for this task - after nipping one top bolt a blade screwdriver used to lever the rudder into its final location. 

There are two 3.2 mm holes provided to allow a permanent location relative to the vertical  spar.   

Fuselage Gap Seal
The junction between the fuselage and vertical spar has a noticeable gap this was sealer with Selleys Black SolarFlex silicone sealant. Two masking tape verticals wers applied and a bead of silicone added. This was then wiped using a disposable towel and allowed to cure.

First application of sealant
Tape removed after wiping silicone

After curing a second application was applied repeating the technique outline above.

Electrical Connections
The aircraft has been fitted with a white tail  light and red strobe. As an ultralight it cannot be flown at night but as it is in full camouflage it was decided to make myself a little more visible.

The connection was finished using the factory access panel to complete the connection. The plug is mounted on a tang located on the second rear bulkhead. the connecting cable in the fairing has a service loop to allow it to be extracted for servicing as shown below.

Final assembly before electrical testing / painting
The rivets shafts are a perfect match for the rivet nuts bore
and providing a perfect temporary fixing

Comment
Took a long day to tidy up all these small loose ends and others but it is now ready for paint preparation. Once painted the clevis bolts will be fitted, pinned as I want the rudder to be able to be deflected for painting.

Bits & Pieces - No 4

This blog covers the reinstallation of the stabs and other small items at the rear

Overview
After the repair of the stab it was time to assemble the tail for the final time.

Installation
This work was described in details in the blog category Elevator Stabs.

Rudder
The nose of of the fiberglass fairing was not aligned with the rudder mass balance cover and it was decided to fit a 0.025'' 2024-T3 at the end on both sides to engage by about 20 mm under the fiberglass fairing on both sides. The fairing was securely locked in position and after riveting the aluminium fairing back in position additional rivets were added to the fairing using the existing rivets lines. 

Alodined 0.025'' strip ready for closure

The final electrical plugs were added, checked and tidied up to allow installation.

Elevator Fairing Extension
The starboard faring was short when installed and aligned with the mass balance faring and it was decided to used the open end to add auto filler. The filler was supported until cured on a piece of scrap aluminium. After curing the aluminium was removed and the filler sanded to shape top allow installation of the fairing.

Elevator Stab Installation
The front attachment straps were install ready to accept the elevator stab with a scrap block of builder foam to support the stab while the front bolts were installed. The lower bolts were installed first using a 3/8'' open ender then the top bolts as these have the best access. All bolts were only nipped to allow the front bolts to be installed. The yellow line marking the high point on the tapered packer was critical to correct installation.

With the rear bolts the rear spar was jacked up using the foam block and a combination of 1/4'' drives used to install the bottom AN4 bolts - finally the upper AN3 bolts were installed into the factory captive nuts.

A final check of the level was taken though little could be done to change it. The front longeron was used by the factory as the datum when setting the wing alignment and with the digital level zeroed and the level was checked at the rear - all seemed OK so all bolts were torqued and marked

Elevator

Rubber dust seals

The elevator was now reinstalled using the 5 mm unbrako bolts. Doing this by oneself is not recommended but it had to be done. With the rubber seals in position installation started at the starboard outside hinge with each one inserted until the port side was reached. Installing the bolts while grimly holding the elevator using the bolts was ruled out and 3 mm cable ties were inserted across the four [4] points. These were chosen as they are pointed and insert easily with one hand while acting as nylon nails.

At this point the bolts were inserted one by one starting again at the starboard side. To allow the bolts to be torqued a standard allen key was cut to fit.

Note: These bolts are called up now as AN3 and the tool that was described previously is invaluable as you need to guide, force and keep hold of the bolt by its head

Rudder Stab

The rudder stab was now fitted using the six [6] attachment point at the rear of the fuselage using AN3 bolts. once fitted the final task was to install the front bolt. 

Previously a captive floating nut was installed on the fuselage attachment and without it I cannot see how I could have done up the bolt. The usual collection of 1/4'' drives were required to access the bolt requiring a dummy nut to be fitted into the socket to allow pressure to be applied while rotating the bolt. 

Finally the rudder hinges were installed using four [4] AN3 bolts each.

Flash photo taken late on a Monday night before leaving to go back  home

Comment
This is the first major progress in a long time but like all these tasks it is only the cumulation of may days of small tasks

Will complete the rudder next week and hook up the cables and finish up a few other small tasks and functionally the tail group will be finished. 

The work group lies in the baggage compartment after adjusting the elevator push tube.