27 August 2017

Empennage: Rudder. Redo.

I was anticipating a wait of 2+ years until I could get into a hangar at the airport.  During that wait, I thought it would be a good time to build a second rudder since I didn't like how the trailing edge of my first rudder came out.  The trailing edge of the rudder looked wavy.  The AEX wedge itself wasn't wavy, but the skin itself was due to poor technique.  This was exacerbated by choosing to alternate the rivet orientation (manufactured vs. shop head) along the trailing edge so that the skin was struck by the rivet set from different sides along every other rivet.

When my hangar fortune changed, I had 4 weeks to order and build a rudder in between my professional and domestic affairs.  After ordering the parts, $481.37 and 25 hours of build time later,  I managed to assemble an unprimed second rudder in 25 hours.  I chose to prime only the non-alodined parts, departing from my usual approach of priming nearly everything.

Follows are a few pics during the build.

Substructure (left).  Match drilling tasks (right).

Following back-riveting of stiffeners.

Trailing edge sealed in with sealant (left).  Trailing edge being riveted (right).  This time all rivets were oriented in the same direction.

Upper fairing ready for match drilling (right).


The R-00918 Attach Strips get nutplates attached to them to accommodate the R-911 Rudder Bottom Fairing.  The aft-most nutplates are in really tight quarters.  So much so, that I decided to use two-lug nutplates on them so I had enough room to squeeze their rivets.  To do that, I used my no hole yoke (ground down to fit into tight places).  However, the nutplate attach holes needed to be dimpled prior to riveting.  It's impossible to fit dimple dies in there, so I used the female side of a pull die with a washer to give the nose of the male side the space it needs (left).  It easily go into where it needed to be for dimpling (right).

Here is left Attach Strip with its nutplates attached.

Here is the final trailing edge (after empennage installation in the hangar).  I dare say it's perfect.

Here's a text file of the parts needed to construct a rudder, as culled from Section 7.

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