Trim Tab - Part 1

Trim Tab

Modification - refer disclaimer

The off cut was already modified when the decision to look at an alternative layout however the factory supplied blank skin was now employed.

The lower skin was folded to create a included angle off 80 degrees to create the lower flange. 

A matching end cap was folded from 2024-T3 over size to be trimmed later.

First fitting Tab

The trim tab skin upper edge was marked with mounting hole center line using the mid point of the hinge width as a starting point. 

Next the hinge and upper skin were match drilled at both ends and cleoced. The edge of the tab was positioned by aligning with the point of contact on the loops on the hinge.

The hinge was reassembled onto the elevator using the hinge wire. 

Match drill front cap

The front cap was positioned on the rear of the hinge after removing the skin and 2 [two] mounting holes duplicated. 

Rotated the assembly to check for correct operation and once satisfied marked holes onto the top side of the skin with a factory jig and felt tip pen - drilled 3/32''. 

Reassembled the skin, hinge and front cap - checked operation and then match drilled all holes 3/32''.

Checked operation.

Alignment Jig

Marking front cap

To assist in locating the lower flange of the trim tab a scrap angle was clecoed across the top of the elevator. These were cut and clamped to hold the trim edge in its correct location.

With the upper skin aligned against that angle and the lower skin positioned by hand a point was marked onto the face of the front cap. 

This was repeated at the opposite end and the assembly removed, line drawn and once satisfied the cap was cut to its correct depth and profile.

Trim was reassembled with the base two holes match drilled from the front cap into the folded flange of the skin and pop riveted.

The tab was remounted onto the elevator and the overall visual alignment checked, at this point all holes were matched drilled

Removed and reassembled - again.....!

Ribs
The outer rib was fabricated from one of the ribs supplied by the factory. 

Outer Rib

The next rib to be fabricated is the inner rib as the factory one did not fit correctly on this project - I suspect a error with the angle folded into the tab. This style of rib was taken from the RV series of aircraft. Both were cut from two of the factory supplied ribs. Note the inner rib is recessed to match the depth of the outer rib. The lower rib is pop riveted first then the outer.  

All temporary pop rivets were removed in preparation for priming and final assembly

Inner Rib

The trim tab components were primed for assembly ready to allow installation of the trim drive clevis reinforcement.

This is to be covered in the next blog post.