A neat thing about the RV-12iS: the wings are fully detachable
by Bob Collins, EAA Chapter 54
March 2025
Mark Shanahan and Bob Collins brace an installed left wing before moving to the right wing. Photo: Marlon Gunderson
(South St. Paul, Minn.) The RV-12iS project has been proceeding at glacial pace the last few years. I don’t get out to the hangar at KSGS as much in the wintertime as I used to so progress has been mostly in fits and starts. I had lunch with RV-7 driver Warren Starkebaum, of Plymouth, Minn., a month or so ago and we compared similar notes about our inability to focus on things for extended periods of times.
That has mostly worked out well for the 12 project as the end of projects is a bunch of little stuff that gets put off until the end: things too small to command lots of time, but small enough to allow lots of small accomplishments and keep things headed in the right direction.
Most of our time at this stage of the project involves waiting for an order of two screws, or two washers or any small number of once-inexhaustible parts. A lesson: Van’s is cheap so they’re only going send you barely enough for your airplane so despite the fact you’ve got 150 AN525-8R8 screws, for example, don’t lose any or you’ll be ordering two AN525-8R8 screws and paying Vans’ new flat-$15 shipping fee for the privilege.
As many of you know, I love polished aluminum, so like the RV-7A N614EF, I’ll probably polish this plane (which will be N612EF) and use a generous number of painted swirls and accents to hide where fiberglass ends and aluminum begins. I finished the wings in 2019 so they’ve been sitting around long enough to need some TLC before they went on the plane.
Fortunately, the 12 is perfect for aluminum aficionados because the wings (fairly) easily come off, are light, and can be polished off the plane on a bench. That’s what I did in November and December. Once done, they only needed to be put on the plane when it was warm enough to get some helpers. That time came at the end of February, when EAA Chapter 54 members Marlon Gunderson, Al Kupferschmidt, and Mark Shanahan stopped by to assist.
Chapter 54 members Mark Shanahan, Al Kupferschmidt, and Marlon Gunderson did the heavy lifting when attaching Bob Collins' RV-12iS wings.
In December, Twin Cities RV Builders Group member Greg Long offered valuable assistance in approaching the task
“It's helpful to have three people, one at the wing tip and two at the wing root,” he wrote. “The two at the root can watch for alignment of the connectors and the forward and aft wing spars. Make sure all of the attach points for the spar pins are well greased, including the pins themselves and anti-seize is on the forward and aft wing spars. Have an exhaust spreader available from Harbor Freight, etc. This will be used at one spar pin location to get the pin to go in at the opposite one. “
“Left wing first, you can install one pin (I do the left pin) just enough to start engagement but not enough to interfere installing the right wing. Install the right wing and see if either spar pin inserts okay. If not, you can use the exhaust spreader to better align the spar pin holes on one side and use a rubber mallet to force the other pin in while having someone move the wing tip up and down on the side the mallet is used on,” according to Long.
I didn’t have an exhaust spreader, so the rubber mallet got a workout. The only problem we encountered was were lifting the wing too high at the far end, causing the wing skin to hit the fuselage skin and prevent that last 1/32” or so it takes to get the ginormous metal pins to lock things in place. So we just dropped the wing end and pushed. Voila!
Mark Shanahan and Al Kupferschmidt join Bob Collins to try to figure out how to get close-tolerance pins into the wing attach points.
The only problem was the lights on the right wing didn’t work correctly (except for the landing light). Since SteinAir built the wiring harness, I knew it had to be the connector at the wing tip (that I constructed), and, indeed, it was a pin that’s not sitting securely in the Molex connector. Easy fix.
The only other thing I wish I’d done when the wings were last on in 2019 is read far enough ahead in the instructions to see that I need a 3/16” gap between wing skin and fuselage. I could have trimmed up the skins on the bench any time in the intervening six years. I’ll have to do it now. I can either pull each wing off slightly, or tape scrap AL to the fuselage for protection while using a Dremel tool on the wing skin.
Next step is to begin Van’s Procedures Acceptance Program (PAP) which will include first engine start. I still haven’t put fuel in the tanks and pressurized the system so if that works out fine, things may actually take to the air.
I hope to buy a DynaVibe unit before first flight to balance the prop.
Bob Collins' RV-12iS takes a breather after getting its wings
I do have one tip from this winter’s work for you: Years ago I did the nose gear leg fairing and HATED how it came out because once you rivet the soft hinge material that keeps it closed, you have a near-zero chance getting a hinge pin to smoothly get inserted; the hinge gets too deformed. So I ordered new parts and those have sat in the hangar for years until I needed to cross that off the list of things to be done.
And it’s easy to see why. The hinge is resting on a curved surface. Of COURSE, it’s going to get deformed when each hinge piece is riveted to the fairing.
Observe:
A typical RV leg fairing uses a hinge to keep it closed but riveting it to the fairing causes it to deform.
The trick is to remove the hinge, Wax it up, put tape or a lot of wax on the edges of the fairing and then put down an epoxy/flox mixture and then sit the hinge on that bed of mixture and cleco in place.
Once cured, you open things up, clean up anything that’s oozed out. You now have a flat base for a flat hinge piece to sit on and you can rivet it without fear of deforming.
After the fix. You'll note the rivets are not fully squeezed. This is to avoid too much pressure that would deform the soft aluminum or fiberglass.
You can find more specifics on my EAA Builder’s Log.
https://eaabuilderslog.org/?blprojentry&proj=7YUgVJYf5&e=8KzABgu9O&listcat=&sid=
Bob Collins has built an RV-7A in addition to an RV12-iS. He is a technical counselor for the EAA. His hangar is located at Fleming Field in South St. Paul. He hopes to have the project completed by early summer in order to fly Young Eagles before the end of the season.
