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RV-7 N8ZG
Empennage
Horizontal Stab
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Fiberglass
Wings
Spars
Ribs
Wing Skins
Fuel Tanks
Ailerons
Flaps
Fuselage
Cowling
Engine
Paint
The flap construction process is different than that of the ailerons. A few fat ribs and two skins wrapped around the spar. The instructions claim it's the simplest structure on the airplane. That may be true. We'll see...
Begin
the flaps by cleaning up the spars. File the long edges and remove the burrs, then de-burr the lightening holes. A
2-inch ScotchBrite wheel mounted in the drill press makes quick work of the holes.
Cleco
the flap ribs to the spars. Note that the interior flap ribs are all of the same hand. The ribs in the right
flap are not installed opposite of the ribs in the left. with the ribs clecoed and reamed to the spars, cleco the
bottom flap skins in place.
The aft flanges of the ribs should contact the rear spar bent in to the bottom skins. If it doesn't, shim as necessary to bridge the gap. I didn't see the point in making shims, and bent the spars to remove the gaps. Drill the aft rib flanges to the spars.
Make
the shims for the bottoms of the inboard and outboard ribs. Ream the bottom skins to the ribs. Clamp and drill
the hinge blanks to the flaps. Take it all apart and de-burr the holes.
Machine countersink the bottom flanges of the flap spars and dimple the top flanges. Put it all back together and cleco the top skins in place. Ream the skins to the ribs, then ream the span-wise runs of rivets that join the top and bottom skins.
Make
the FL-706A braces from angle stock. Make the bends in the FL-706B braces. I clamped the brace in the vise on
the bend line, pulled on it with one hand and smacked it with a dead-blow mallet. Wear gloves - it hurts when
the tail end of the brace rebounds from the hit. Fit the FL-706A and FL-706B braces to the flaps. Ream the holes
for #30 rivets.
Take
it all apart and de-burr the holes. Clean and prime the parts as desired or indicated. Dimple the holes in the ribs
and skins as indicate on the prints.
Rivet the FL-706A braces to the front spars, but take care to leave
the holes that will attach the ribs un-riveted. Cleco the flap ribs to the spars and cleco the bottom skins back in
place. Rivet the aft rib flanges to the rear spars.
Cleco
the top skins in place and remove the spars. Set the span-wise line of rivets that join the the top and bottom flap skins,
then rivet the interior ribs to the skins. Do not rivet the inboard and outboard ribs yet. The instructions
encourage you to use a cradle to position the flap assemblies for riveting. With the flaps in the cradle (TE down), I
couldn't reach the rivet lines and control the bucking bar in the narrow space. I stood the flap on-end on the floor
and used a bungee cord to hold it against the bench. None of my bucking bars would reach the rear row of rivets, so I
used one of my pneumatic yokes to buck the rivets. Here's one of the very few advantages to living on base - I can
generally run home for lunch and bang a few rivets.
Remove the inboard ribs from the flap assemblies. Clamp, drill, and rivet the nutplates for the pushrod attach bolts to the outboard ribs. The rivets must be flush to clear the FL-706B brace. 3/32 oops rivets are just the thing for the nutplates. The rib web is just thick enough to accept the countersink for the smaller head size. After the nutplates are riveted to the ribs, rivet the FL-706B braces to the ribs.
Cleco the ribs to the flap assemblies again. Rivet the inboard and outboard ribs to the skins.
With all the ribs riveted, cleco the flap spars in place and use blind rivets to join the spars to the forward flanges of the ribs. Then set the rivets that join the skins to the top flanges of the spars. Cleco the flap hinge to the bottom spar flange and rivet the skins and hinges to the spars.
The flaps are finished!