Elevators - Part 1

Assembled both frame's as shown in the factory drawing's using clecos. The factory has identified each rib with letters making the task easier. The extra rib for the mass balance cover has yet to be installed on the assembly's shown below.

Elevator frame trial assembly

Trail fitted the skins to confirm that they were correct for both frames. Either skin will fit but as clecos are added  and if the incorrect skin is fitted the elevator will begin to distort depending on where the start point was. If correct all the holes will line up easily and the trailing edge will remain straight. 

Errors can happen, so check!

Why fabricate the trim tab?
In Australia to meet the 51% rule some fabrication is required by the builder when the kit was analysed under CASA regulation AC21.29. This rule allow a builder to gain full points for fabrication and assembly of an elevator trim tab. The points gained are then applied to the factory assembled wing as both carry equal weighting in the chart. 

When you examine the chart it's a way for the regulators to force some fabrication skills to be developed while still allowing other major tasks to be done at the factory i.e. an quick build wing kit.

Trim Tab Skin
The starboard [left] elevator has the trim tap installed and this requires fabrication by the builder. The factory supplied all the necessary folding's but in raw form only.

Marked out the trim tab on the skin surface to the factory supplied dimensions - Check - THINK - RECHECKED and only then cut. 

All cuts were undertaken using the methods outlined in the blog metal cutting. A piece of 6 mm plywood was inserted between both sides for this task.

Trimming edge of skin

Once the cuts are made begin at the separation at external edge, it was found if the cut's are deep enough start at the outside edge and separate using a tearing motion and where thicker area's are encountered a set of snips will cut that area of the skin easily. 

Dress all edges smooth and nick free.

Note: Drill a 5/32'' [4 m]  hole at each corner and cut to this - important! 

Tearing cut line

Cutting skins

Off-cut becomes the tab skin

The resulting scrap will become the skin for the tab when it is trimmed later in a following blog. 

Placed to one side for reuse.