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