Bits and Pieces
Rebuilding After a Flip-Over
By Ian Brown, Editor – Bits and Pieces, EAA 657159
You were promised an update on the rebuilding of the editor's RV-9A after its flip-over in September last year. After time spent in Florida this winter, it became time to start work in earnest, and what better way than with a friend who volunteers to help? You don't always have the opportunity to pick your volunteers or their skill sets, so if they have appropriate skills and a disposition toward working easily with you, you're lucky.
When my friend, Doug Martin, volunteered to spend 10 days working on my plane with me, I was more than lucky. I felt like I'd won the lottery. You see, Doug's interests, from his youth all the way through his career, included forming, constructing, and often repairing in both fibreglass and sheet metal. His passion for motorcycle racing involved innovating new fairing designs and windshields and repairing them when they got bent. His manufacturing engineering role in the appliance industry taught him more than most of us could ever hope to know regarding sheet metal forming.
Doug at the drill
Now I don't buy lottery tickets, but this amazing skill set was a perfect match for the unknown part of my rebuilding project. Having had prop and engine restored to good health, and ordering the clearly broken parts from Van's Aircraft, my anxiety centred on whether the firewall, its adjacent flooring, and the engine cowl could be restored to perfect condition. I asked my wife and she said, "Of course it can!" And she knows infinitely more than I do about building aircraft! She, after all, helped buck a few rivets, and she was my quality inspector throughout the project.
I had previously removed the deformed aft lower side and bottom panels that had either tears or serious buckles. Imagine the forces involved when the aircraft flips over and the vertical stabilizer comes into contact with the ground. The main damage was where the aft fuselage meets the baggage compartment bulkhead. Just before Doug arrived, I managed to remove the forward left side panel. That's when what was left of the airframe became seriously floppy.
Down to the bare bones
Stabilizing the remaining structure with lots of clecoes became a must, although without anything forward of the firewall and no empennage, the remaining airframe was very maneuverable and well supported on a couple of sawhorses.
Firewall buckled at engine mount
In assessing the firewall damage it became obvious that removing at least one forward side skin was a very good thing. It gave excellent access to both sides of the firewall and made it very easy to remove those stringers and structure that would need to be remanufactured. We set the last rivets on the new pieces after Doug had demonstrated how to "sneak up on" the buckling in the firewall and floor from the edges of the deformity.
New stringers and flattened floor
I had the pleasure of watching an artist at work. The result was a perfectly flat firewall and floor that is structurally sound with nothing held in tension against the new rivets.
A flat firewall is a thing of beauty
On to the engine cowl, my remaining cause of sleeplessness. While taking a break from drilling out rivets and making new parts, we had assessed the damage and concluded that the cowl was at least worth a try at salvaging. I learned that epoxy resin, though excellent, is not itself capable of carrying the loads to ensure safety. Repairing cars and boats does not involve the same concerns as an engine cowl or a 150-mph motorcycle fairing, for that matter. I learned that broken glass fibres can't just be glued together. Another lesson was to understand that the least amount of resin possible will give the best result. The technique involves grinding out a V-groove and laying up new glass mat with just enough resin that there is no air trapped - but not so much that it looks at all wet. Patient dabbing and prodding with a Popsicle stick proved to be an excellent method for applying just enough resin.
Rebuilt engine cowl before refinishing
The result, as you will see from the picture, is an engine cowl that just needs the smallest of refinishing work to get it back to pristine condition. I might even be able to spend some time making the piano hinges fit a bit better. It's always been a struggle to get those hinge pins to go in smoothly.
So what, if anything, was I able to exchange for my lessons in metal in fibreglass forming? Well, honestly, not very much. I think I'd had more experience in removing and setting rivets. I hear there are 14,500 in an RV, though I never counted them all. Drilling through the machine head, snapping the head off with a punch, and pushing the shop head out with a tapered punch became second nature to both of us, with only maybe a couple needing wider rivets.
If you're faced with a similar challenge, and I sincerely hope you are not, I wish you all a friend like Doug. Not only was he supremely skillful, but he's a great, giving ally. And this week I will sleep well, knowing that what remains is "normal aircraft building" like I did the first time.
I was fortunate enough to locate an already built empennage at an excellent price, and adding the plastic end caps will keep me busy for a while. It was built at the Alexander Technical Center where the purchaser tells me the instructors did most of the riveting, and the quality is evident. Everything is primed inside and ready to go.
What's next? Well, I'm awaiting a rather large crate from Van's that will include the canopy, canopy frame, engine mount, nose gear, aft fuselage panels, and stringers. I'll give you another update when I make the next significant leap forward. For now, it's time to get Bits and Pieces out to you, and maybe cut some grass. Thanks, Doug. I owe you.