Stab Repair

This blog covers the repair of the damaged front spar in the elevator stab

Overview
While it was easy to create this mess fixing it was never going to be easy In a previous blog it was decided to install a new spar but to do this would require a jig to hold the stab in the original factory alignment.

The factory asked me to hold and has supplied the necessary drawing, advice and parts to manufacture then install necessary components to negate the damage.

Factory Aerobatic Kit - reference

Installation
Both nose skins and lower skin at one side were de-riveted to create the necessary access. 

The next task was to remove all the solid rivets, this was done by locating the dimple on the head, drilling through 3.5 mm and then cutting off the flared end allowing the head to drop away. Finally the floating nuts were removed allowing them to be relocated onto the new doubler. 

A new angle doubler was fabricated from 2024-T3 with the spar face flange extended 100 mm past the damaged area tapered to 10 mm at the ends.


All new components were alodined before installation.

Both internal ribs that were affected by the installation of the extended angle stiffener were removed. All the factory doubler's [shown green in middle image] were then removed to allow the installation of the extended angle doubler based on the factory angle doubler [shown in yellow].

In order starting at rear spar
Original Doubler [green]
Extend Angle Doubler [yellow]
Original Doubler top [redundant]
Doubler clecoed to spar [to be reinstalled internally on t/s angle]

Both plates installed

First step was to reinstall the long factory straps [green], next the angle doubler's long and short were clamped onto the inside spar flange face then match drilled using the existing 1/8'' holes in the spar flange. 


A spacer was fabricated to fill the gap between both angle flanges and fixed using thin double sided tape.

Using the front plate all holes except the outer edges were drilled including holes from the existing doubler from the inside.. Next the inside plate was installed, lower holes drilled, clecoed and finally the 4 mm OD holes. 

New top strap and old one shown for reference

With the internal angle stiffener in position and running under the damaged area a new top strap was fabricated from 2024-T3 0.040" aluminium sheet and alodined to cover the damage area.

With a final check all rivets were then fitted at the spar face only.

New connection riveted on spear face

Ready to close

Comments

I'm getting over it

Fuel System - Firewall

This blog cover the installation of the fuel system firewall forward

Overview
The installation of the fuel selector was governed by the ergonomics of the fuel selector location. Originally factory selector was located on the floor in front of the pilot and the builder found this personally unsuitable, since then this has been revisited by the factory and raised up in a new counsel.

The location and reasoning was outline in a previous blog in March 2016.

Factory selector location - all the lines are located under selector panel

Installation
The lines are fabricated with 5052-0 aluminium tube, flared using a 37 degree flaring tool. All fittings are aluminium AN 6 with the specialty fittings manufactured by Aero-Flow and other suppliers. 

The use of specialty fittings was required to obtain the necessary radius's and connections within the available space as these cannot be achieved with tube and hand tools. 

The 45 degree fitting on the fuel return are to be replaced
with two [2] x 90 degree fittings to remove a foul
with the undercarriage trailing arm

A Facet pump was used to allow the use of AN fitting through the firewall installation.

All threads have a drop of thread locker to prevent slippage and to act as a lubricant at assembly

All lines are covered with 3/8'' fire sleeve achieving a tight fit on the aluminium tubing with all ends dipped into high temperature silicon diluted with Acetone. Excess material was then wiped onto the end and worked in using a scrap piece of tubing. 

Preparing hose end - note the fit to the tube

Fitting last nut to assembly
All ends will be sealed with 12 mm worm drive clamps

Overview
The result meet the original design requirement but there is a caveat. With the mount moving back 30 mm and the tight interface with the undercarriage a large amount of precious space was lost. In particular a custom air filter installation will be now required and a few more fittings added to clear the undercarriage trailing link.

Engine - Reservoirs

This blog cover the mounting of the oil reservoir for the supercharger and engine.

Overview
After searching there are no details on a stand alone mounting bracket for the Rotax 912 oil reservoir so this meant there were no ideas to use but after some thought using weight as the guiding principle a simple U bracket with band clamp was developed.

Installation Oil Tank
The bracket was fabricated from 25 x 3 commercial aluminium flat bar with bands created with two [2] x 100 mm OD worm drive clamps. The clamps chosen were purchased at a local auto store featuring a long length of un-perforated area. To prepare the bands one had the worm drive cut off with the other cut at the start of the perforations, finally both bands overall length were trimmed to start at the fold placing the worm drive about the center of the assembly

Both bands were drilled to place a two [2] x 1/8'' pop rivet at 10 mm from the fold line and the end of the bracket with the holes matched drilled through the bracket. All holes for the lower mount were drilled to suit M4 screws in the bracket with both holes placed at the edge of the clamp and at the edge of the fold.

Note: These locations selected for the rivet and screws in the void created by the interface with the oil tank. 

Both brackets were alodined then bands riveted to both bracket ensuring that they closed up before riveting.

Oil tank moved to other side to avoid fouling sensor on supercharger
Note relocated to the starboard side

The Adell clamps were fitted to the engine mount then the lower mount fixed to the engine mount via the clamps. With this bracket in position, the tank was now installed the band tightened, next the top side was wired to the engine mount. 

With the lower Adell clamps fitted the upper one was slipped into position and its mounting point marked onto the upper bracket. The bracket was removed and the hole was drilled and tapped M4 and a screw fitted with thread locker.

The assembly was reinstalled and all points tightened.

Note: Ensure there is space for the engine mount rubber to pass the clamp for the oil reservoir

Instillation Supercharger Oil Reservoir
Two spreaders were fabricated to use the factory mounting points using 25 x 3 aluminium bar with 20 mm extension past the tank mounting to accommodate the Adell clamps. The lower bracket uses two [2] Adell clamps  with the upper one scalloped to clear the reservoir inlet. The bars were fixed using S/S M5 x 10 cap head screws with the Adell clamps fixed with M4 screws.

Relocated to the port side

Comment
All the mounting holes would be tapped for ease of installation if doing it again. After a trial installation with a dummy engine and cowls both reservoirs were swapped to opposite sides with the oil reservoirs on the starboard side and the supercharger reservoir on the port side.

Another job finished..!

Update
A trail check using a dummy engine proved that all the parts with fit as intended. This engine will be used to manufacturer all the necessary brackets etc for the final installation of the converted engine.

Trial install - note final location of oil tank [crank, pistons are removed] 
This engine was removed and was found to be close to failure.  I was flying behind this few hours before my L2 noted the issue after flying the aircraft back to its base
over the Blue Mountains....!

It will all fit....!