Restoring the A-10D Mitchell Wing
SN# 275
By
Episode IX
Fixin’ the Rudder, Propped Up, Paint, In the Belly of the Beast, Liability Lightning and the End of Ultralighting, Alternative Realities
This guy really was Michelangelo with a welder. The rudder hinge assembly had returned from the fabricator and it looked very good. I’d made a few minor changes to the factory design to make it stronger, but in every other way it was nearly identical. While it was being welded I set about removing the old hinge assembly and suppressing the feelings of déjà vu. I pulled the end plate off the wing and marked the new assembly for drilling using the plate’s old holes. Overall, the replacement went pretty well and it wasn’t long before I had the rudder back in place. It was here I discovered that when the rudder was folded the rudder lock was no longer usable. Of course, this made sense, now that the rudder rake angle was where it should be. Unfortunately it was just another of those little repercussions that had escaped me. Moving the rudder lock was not a big deal, but it did leave me with a small, tight grouping of five, eighth-inch holes in my wing. My response to this was to drill out a few of the rivets that held the wing patch doubler in place and slide a scrap piece of sixteen thousandths 2024 aluminum between the patch and the upper wing skin. It was a very tight fit which assured me that the new piece would not travel, so I reinstalled the rivets in the wing patch and went to the next problem, (Actually things were not as slick as it sounds. I was making the repair during a thunderstorm that knocked out power to my neighborhood with three rivets left to go. As a result, the last three were pulled in the dark and I had a hell of a time finding my way out of the garage.).
A week later my prop arrived from Prince Aircraft. The black carbon fiber was beautiful. It was also remarkably light, lighter in fact that the old wooden prop or the UltraProp. It was, however, a steeper pitch than I expected. I had given Lonnie Prince free reign in its design, in order to give me the most efficient unit possible for a combination of climb and cruise, so I rather expected that it would be slightly outside the norm. Still, when I get the chance, I intend to call and find out what he had in mind.
The next issue would be mounting it. The four bolt pattern was an exact match to the Hegar reduction drive prop hub, but getting AN quality 5/16” prop bolts of the right size and thread length proved to be tougher than I expected. As a reference I pulled out the old bolts and noticed that they had originated from some unknown hardware store. The heads had been drilled rather badly to accept safety wire and did not inspire a great deal of confidence. Nevertheless, they served to help get the measurements I’d need to order four new units with the right grip and thread length, and with professionally drilled bolt heads. My first attempt at using AN5H-26A aircraft bolts was less than successful. While the overall length was right, the grip length was too long and the thread length too short. Thus, I’ve begun the quest for a set of bolts I can depend on to keep the prop attached to the engine. So far I haven’t been successful.
While all this was going on I was in contact with Chip Diggins to arrange for the painting of the wing. I had already consulted with the local Sherwin Williams automotive paint supplier and had shelled out some pretty heavy bread for two quarts of their self-etching olive-drab primer and another two of their white along with reducer, hardener and surface prep cleaner.
After some scheduling conflicts, the planets spun into the right alignment and Chip and I were finally going to be in the same place at the same time with the intention to paint the wing. All I had to do now was figure out how to get the three sections of the wing to his paint booth in Massachusetts. Because we both had limited time the most direct method was simply to rent a truck and carry it north. Unfortunately, the time slot we’d agreed upon coincided perfectly with the summer return of an untold number of college students from dorms and apartments across the east coast. There was also a sudden interest in moving furniture on the part of every third resident in RI, all of which meant there simply were no trucks to be had. Finally, after marching down the list of phone numbers I’d collected, I found one 24 footer on the back lot of a U-Haul dealer that was available for Saturday only.
“Can youse drive a standud?” the voice on the end of the phone asked. “It’s a diesel, know what dat is?”
I assured him that I was conversant with both.
“Okay, den, but I got a waitin’ list so’s youse gonna hafta bring it back by midnight, right?”
After some thought and a quick call to Chip I called back to put my name on the truck.
“Okay, I’ll pull er around da front for ya’s.”
I arrived at the appointed time and date to find the dealer sucking a Tootsie Roll Pop, eyes glued to a computer terminal. He was evidently having some technical difficulties that could be corrected by selectively kicking different parts of the computer tower beneath the counter.
Our eyes met and he immediately transferred his burning hatred of Microsoft directly to me.
“It’s out front,” he grunted. “Got a third of a tank a fuel. Bring it back da same so’s I don’t gotta charge ya.”
On this positive note I picked up the key and walked to the parking apron in front of the building. It was obvious that the truck was a veteran of more furniture moving campaigns that the average man could imagine, as evidenced by the drooping and loose trim pieces and a variety of battle scars inflicted by any solid object that may have had the misfortune to get in its way. Somewhat daunted by this, I swung up into the driver’s seat to be greeted by the reek of diesel fuel. I now understood why the only parts on the truck that were clean were the windows. They’d never been rolled up.
I read the long, greasy list of do’s and don’ts pasted on the visor and in various other places in the cab, finally getting up the nerve to turn over the engine. To my great surprise, it started with only a minor black cloud of exhaust. From this point all I had to do was to release the parking brake and head for the open road. Overall, it was not completely unexpected that the parking brake, when released, didn’t. Or, at least that’s what the warning light indicated. Climbing down from the cab I retrieved the U-Haul guy who said he knew what the problem was. He solved it by delivering a solid kick to the brake handle which caused the light to go out immediately, apparently in fear.
Back in the cab again, I revved up the beast beneath the hood noting that the hood itself shifted ominously to one side when I touched the throttle. Starting to feel like a bona fide trucker I swung down over the bent metal steps and marched to the passenger side of the vehicle where I found the hood latch still open. I socked it down hard, reassuring myself that, yes indeed, someone who cared had really been doing maintenance before I got there. Or at least something like that.
Leaving the lot was a bit of a challenge, because in order to back up, one ordinarily relies on rearview mirrors that stay locked in one place. The ones I had weren’t so inclined. Actually they were inclined, and bent, which limited my view to the first five feet of asphalt ninety degrees to either side of the truck. The view did change, however, depending upon the size of the pothole or rock I hit on the way out the driveway.
Getting back home was quite a learning experience. I learned, for instance, that two of the five gears required more care that the others. Fourth was there if I cared to take the time to find it and third was missing completely. Therefore I didn’t care about it at all. I also learned that at any speed above forty the front end would vibrate like a Saturn V rocket on blastoff, and there was a 90% chance it would go where you pointed it. I never did learn what the source of the occasional, thunder-like boom was back there in the box and decided not to pursue it.
When I reached home I took the prudent measure of parking the beast out on the street. With my luck this thing would be loosing more fuel and oil than I wanted to have anywhere near an inhabited area. I also dreaded having to deal with the OSHA, EPA and Superfund people since the receipt of the Alodyne and Aloprep (both of which I turned over to the state’s hazardous waste people). The way I looked at it, if it was on the street it was the town’s problem. Of course, this meant that I would now have to move the wing sections four times farther than I’d originally planned.
I unlocked the rear door and pushed it up until the built-in spring took over and nearly lifted me off my feet. Ah, an empty space, just waiting to be filled with the dreams of a more than middle-aged UL enthusiast. Well, not quite empty, I still had to deal with the two metal wheel wells that intruded into the center of my field of dreams. Fortunately, I was prepared for such an occurrence having invested in a dozen cheap bed pillows and a few boards of closed cell pink insulating foam.
So, with the temperature pushing ninety and the humidity off the scale, the wife, kids and I moved the massive wing center section from its cozy garage perch to the uncertainty of the beast’s belly. After strategically placing the foam and pillows we were able to get the other two sections of the wing secured and the rudders wrapped and carefully placed out of harm’s way. I then wrestled the door back into the down position, locked it and climbed aboard for the trip north. Fortunately, this was fairly uneventful except for the occasional dizziness due to exhaust fumes and the smell of fuel oil.
Once at Chip’s place, I yielded to him the honor (and liability) of backing the truck into his driveway. That done, we opened the rear door and he inspected the job. He was not prepared for the large size of the wing center section. Still, he thought, with some planning we might be able to do it. And so it was that we managed to actually hang it, leading edge up inside the booth, with the other sections hung like sausages nearby.
I produced the painting materials along with the data sheets while he pulled out his HVLP gun and space helmet. I then pulled on some latex gloves and began cleaning the skin surfaces with the prep solvent. It wasn’t long before the compressor was humming and the air was filled with the smell of new paint. Naturally, there were a few kinks. The major one being small remnants of the car wax I’d put on the wing the previous year that clung invisibly to various parts of the skin, only to be discovered as “fish eyes” after the paint hit them. Sanding them out was not my favorite activity, nor was removing large sections of paint with solvent for repainting when sanding wouldn’t correct the problem. Needless to say, the painting process was not fun. It got worse when we realized that I’d come up short on the estimate of how much paint I’d actually need, which meant another trip to the auto parts store, and that I’d have to leave all three sections of the wing there longer than we planned. It also meant another truck reservation; something I dreaded even more. Such are the ways of fate and bad planning.
Two nights later I used my own truck to ferry the additional paint north along with the stabilators and wing tip fairings, which I’d cleverly forgotten to bring the first time. Chip, however, was unfazed, and did the rest of the painting during the weeknights in preparation for another big move as soon as they were done. In the meantime, I located another truck, this time from Ryder, and reserved it for the following Wednesday night. The rental agent was considerably farther away, but the extra cost and travel time was worth it. I tossed all the padding and foam into the back of the truck, climbed into the cab and kicked over the diesel.
Chip was waiting anxiously to get the behemoth wing out and regain control of his spray booth, as he had other jobs already lined up. We quickly inspected the finished product and then moved the sections into the truck. It wasn’t perfect, and there were still some of the annoying fish eye flaws, but overall, it beat hell out of the pitted aluminum I started with. And, any further corrosion had been stopped in its tracks. Yes!
It was a long night, delivering the wing sections back to my garage and dropping the truck off on the other side of the state. It was also expensive, but I now had a white wing with yellow drag rudders. Unfortunately, the wing tip fairings were loaded with fish eyes, chemical flaws that resisted even the prophylactic coating of gray primer I’d put on the fiberglass before hand. These required considerable work, sanding, cleaning and repainting before I was finally able to call them acceptable.
The next problem was to figure out a way to attach the wingtip fairing to the newly made rudder hinge assembly. While the welder was indeed talented, he’d made a minor shift in the position of the reinforcing webs moving them slightly inward for a better weld. Unfortunately they were now out of reach for even the longest pop rivet I could find. After considerable tinkering I decided to go with small diameter, stainless steel machine screws which would screw into threaded holes in the webs. I cut and shaped some small aluminum tubing sections which slipped over the screws to support the fiberglass fairing and prevent it from deflecting inward and cracking. A washer under each machine screw head would relieve stress from the outside. As a safety precaution I’d also use Loctite on the screws when the fairing finally went in place.
Nearly a month later, after endless business trips and dealing with a number of other issues, I organized a neighbor and a good friend who were willing to devote an hour or so of their Sunday morning to helping put the center section of the wing back on the airframe. After carefully choreographing the wing’s move from the garage to the backyard hanger, the three of us discovered that we were dealing with a major pain in the ass. We could have easily used another set of hands to help “coax” the holes in the lift blocks into alignment with the wing attachment points. On the bright side, my vocabulary expanded into several new areas and I realized that there really are good friends out there. When it was done, I was shocked to realize that it actually looked like an airplane again; one that might even fly.
Naturally, every silver lining has a cloud around it, especially with this project. While all this happy restoration stuff was going on, my personal cloud was billowing to new heights and darkness. At the next ultralight club meeting it was announced that the owners of the field had stopped flight operations until all the club aircraft could be proven to comply with FAR103 and each pilot could produce one million dollars of third-party liability insurance. At nearly the same instant, another small airport in the area, that was a favorite fly-in place and had collected a number of ultralights as part of an EAA Chapter there, put out a letter stating there would be NO further ultralight activity, period. Anything that flew there had to have an “N” number and all pilots had to have an FAA issued pilot’s certificate, plus insurance. Good news travels fast I guess, because when our group tried to negotiate a move to another nearby airport, the airport owners found it acceptable only if the ULs went somewhere else.
The club officers, however, were undaunted and began exploring ways around the restrictions. The most obvious was to stay at the home field (where they were at least welcome). This meant finding out which of the ULs were 103 compliant and getting their owners USUA pilot ratings along with the new USUA ultralight liability insurance (later determined to be unacceptable by the field owners). For those found to be “fat” they could either wait to register under the Light Sport Aircraft rule which may or may not happen in this decade, or try to register them as amateur built Experimentals. The process is on-going, with many members simply folding their tents and leaving while others are attempting to comply with the regs. All in all, it’s an ugly situation, especially for me.
The A-10D in its fully restored configuration will very likely tip the scales at more than 254 lbs. This means I have three options, none of which I really like. The first is to bite the bullet and register it as an amateur built experimental glider. I could then fly it legally using my existing FAA Private Glider certificate with a motor-glider endorsement. It took awhile, but I now have the motor endorsement in my sailplane logbook in case I go this route. It has the advantage that I’d have an “N” number and could fly it into almost any airport, assuming I had the right gear on board. It also means that I can more readily get liability insurance. On the down side, I’d have to have it inspected every year by an A&P or apply for the repairman certificate, if they’ll issue it and do that part myself (the Mitchell Wing A10D is not on the FAA’s 51% list). The real hurdle will be to apply for and get an airworthiness certificate. Although I’ve tried to religiously follow all the best construction and repair practices, I may have missed something, or perhaps the design itself will not meet the expectations of an FAA inspector or DAR. I simply don’t know. Even though I’ve rebuilt this aircraft from the ground up using pieces of the original, I have no idea if that will fit under the amateur-built guidelines. I had never intended to go the amateur-built experimental route, so I never bothered to keep a builder’s log complete with photos. What you see on this website is all there is, along with a large stack of receipts representing a large amount of cash I’ve poured into this thing over the last four years.
In order to get some answers to these questions, I’ve decided to use one of the benefits of my EAA membership and contact one of their technical advisors. If he gives me the thumbs down I’ll drop back to option number two.
Option 2 is to rip out everything non-essential and attempt to make the 254 lb. limit. This would mean turning it into something close to the Ameriplanes A-10B ultralight version of the Mitchell Wing. Starting with the engine I could dump the starter and the intake silencer along with redundancy of the electric fuel pump. This could be replaced with the sometimes hazardous squeeze bulb. The pump primer could also go. What I’d be left with is a louder (and more annoying to the neighbors), more difficult/dangerous to start engine. Okay, so what’s next. The five gallon tank could be replaced with the original 2.5 gal unit between the frame tubes (and the pilot’s legs). The pod and windshield would disappear along with the podsterior and the wheel pants. The six inch tires could go, being replaced by the original four inch wheels (not great on a grass field, but hey, who you gonna call?). Oh, and there’s that brake on the nose wheel that can get scrapped. After all, that’s why God invented Reboks. Let’s see, if the starter is gone, the battery and electrical system can go too. And then there’s the instruments. Let’s just assume I rip out the panel altogether. Somewhere I have a Hall’s wind speed gauge that could be the airspeed indicator. For an altimeter, I could get a digital watch with built-in barometer function. Tach? Hmmm, I don’t have one on the Lazair, and it has twin engines. The pilot uses his ears. Maybe I can dump that completely, or if necessary, a digital Tiny-Tach might work. Vertical speed indicator? Gone. Pellet Variometer? As a glider pilot I hate to part with it so I’ll put it on standby. EGT / CHT gauge? With less than an hour of flying time (assuming I keep some reserve) on 2.5 gallons it I doubt they’ll matter much except for tuning the engine. Color them gone. Oh yeah, that new $200.00 seat cover and cushion can bite the dust too. Discomfort is a relative thing.
Now, what would I have to add? Some sort of stirrup arrangement I guess, to keep my feet from falling off the rudder pedals. If I was really pressed and wanted to sell a kidney, I could dump the Rotax 277 altogether and go to a Hirth which is considerably lighter.
Voila! It’s done and I’ve only wasted four years going down blind alleys in the process. Okay, to support this option and get the liability insurance I just have to get the USUA pilot rating. Unfortunately there aren’t any USUA BFI’s around. The last time I looked for one that actually taught students I found I’d have to go to New York State. I think he was charging $100.00 per hour. Hopefully it hasn’t gone up. Of course it won’t relate much to the way the A-10 flies, but I’ll have the ticket to get the insurance, assuming that doesn’t disappear in the meantime or get rejected by the FBO.
Option 3, sell both ULs for recyclable scrap, take out a loan and go back to flying the German glass slippers with the nearest soaring club.
Well, that’s it for this time gang. Hang in there for Episode X to find out which option gets the nod.
Let’s hope your day has been better than mine.
Episode I Episode II Episode III Episode IV Episode V Episode VI Episode VII Episode VIII Episode X