Nut Plates

As part of the assembly the spars of the aircraft tail require nut plates allowing installation and removal of various components without access to a nut. This task is was accomplished using simple jigs and micro stop countersink.

Drilling Nut-plates
Using a piece of dressed timber, drill a 5 mm hole through then using a #8 screw  of sufficient length to engage the plate. Insert the screw through the hole and then fit a nut plates supplied with the kit and drill a 1.5 mm hold through one of the lug mounting holes. Insert a a discarded pop rivet shaft as a locating pin as it adsorbs the torque of drilling and its a true finger saver.  

Drill the hole on the opposite side to the pin 3.2 mm [1/8''] through, remove and refit the nut-plate and drill the other side and de-burr. 

Now all that you do now is the rest - Joy..!

Drilling Spars Nut Plates
While some of the spars in this kit had the mounting holes for the rivets to fix the plates drill they were not on the elevator stab spar but all require countersinking. Locate a #10 bolt or screw and fit into a unmodified nut-pate to a depth to secure the two items. Trim off the head of the bolt with a hacksaw and you have a low cost drilling jig. 

Mark a straight line across the center's of the factory holes using a felt pen and insert the exposed shank into the factory drilled hole and align the two mounting holes with the line. Mark and drill the first mounting hole, secure the nut-plate using a cleco from the rear then drill the next hole. 
Repeat for all the mounting holes as specified in the plans.

Countersinking Nut Pales
If purchasing a new micro stop investigate a slim line for this job especially for those in the rudder fin spar and remember to purchase 1/8'' cutters to suit the selected tool. This builder used an full size economy micro stop that was in the toolbox. 

Note: Countersunk pop rivets have 120 deg NOT 100 deg angle as a solid rivet.

Slim Micro Stop & Cutter

Nut plates should be aligned along the length of the spar especially on the rudder fin. Drill test holes in a piece of scrap and adjust the stop to the correct depth then countersink all the mounting holes and install the plates with 1/8'' counter-sunk pop rivets supplied. When riveting, fix the nut-plate to the spar with a short 3/16'' screw, align hole and pop rivet with the countersunk rivets supplied with the kit.

Countersunk holes have a tendency to find their own centers and are notorious in their lack of accuracy about the hole center-line they are applied on.

This nut alignment was missed by this builder on the rudder stab and resulted in some untidy work to fix the issue. 

Footnote: Countersunk 3/32 pop rivets are available but hard to source and not available from the usual home builder suppliers.
Apex Fasteners have one with a 3.2 mm grip, a bit long but you might get away with it. The gain is not having to drill the lug as outlined and the countersink should fully terminate in the 1 mm spar material.