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Winter Work Part Deux

Joe Horton checks in

By Joe Horton, EAA 513548, for Experimenter

Joe Horton’s KR-2S parked outside the Homebuilders Headquarters at EAA AirVenture Oshkosh 2011, the reward for spending the winter making minor repairs rather than flying.

In the March 2010 issue of Experimenter, EAA member Joe Horton of Coopersburg, Pennsylvania, told us a little about the work he performed on his KR-2S over the 2009/2010 winter, some being upgrades, some being repairs. This past winter he was determined not to go through that again, but rather he wanted to fly. To his dismay, Mother Nature had a different idea, throwing a serious winter all over the Northeast. Taking advantage of his downtime, Joe made some new changes to his plane.

Last winter I took N357CJ home for several months over the winter to perform some maintenance and upgrades, and it took a lot longer than I thought it would. When winter rolled around once more, I said no way, not again this year—I want to fly and have fun. Well, winter had a different idea and decided to be terrible in the Northeast. A few flights here and there, but short days, high winds, and snow cut into the flying time. So I started looking under the cowl at the 3100-cc Corvair engine I installed.

The paint was flaking off the engine mount and was fairly scarred up on the engine parts. There still seemed to be a small oil leak, the dynamo (generator) bracket needed some modifying, and the starter was giving some signs of going bad. Then there was this engine hoist sitting in the corner of the hangar; the die was cast.

Down to Business
The hoist made it an easy job to remove the engine. I just had to disconnect all the engine sensors, some hoses, and a few bolts. I left the prop and exhaust system intact. All the stuff mounted to the firewall was left in place. With the engine removed, I had access to so much that was only visible with mirrors- and severe contortions. The first order of business was to remove the engine mount and inspect it. After all, it is homemade. It had been in place for over five years now and has logged over 560 hours of flight time. I cleaned it up and carefully visually inspected it for cracks or any other damage. Finding nothing at all wrong with it, I took the mount and valve covers and some small parts to a small, local, powder-coating shop.

The Starter
While the parts were at the powder coater, I started looking into the squawks on the engine. The first thing was to replace the starter. I took it to the local auto parts store that offers free testing. The testing is incomplete as they’re only set up to test things electrically. The starter motor tested fine, but I saw that the starter gear didn’t always throw out. In fact the gears were loud, and after several tries it stopped spinning the drive gear out. So a new starter was purchased.

Now here’s where I start to drift into the realm of out of control. I took apart the new starter and brought some of the parts to the powder coater. For the things that wouldn’t be good to go into an oven, part of the powder-coating process, I painted a matching color. (Red is my thing.) With the starter off, the next part to check was the ring gear/flex plate. First I needed to look it over to make sure that the starter hadn’t beaten up the teeth on the flex plate. It seemed to be in good condition, so off to the paint booth with that, too. Normally a starter drives the gears on the outer perimeter of the flywheel, but the modifications required to convert a Corvair engine for flight call for using a flex plate (or ring gear if you prefer) from an automatic transmission to provide the teeth for the starter to drive. This is done as a weight-savings measure. ~Pat

Dynamo Brackets
With these things off the back of the engine, I could get to the dynamo mounting brackets. I had reached the end of the adjustment slot for belt tensioning. So now off came the dynamo. Elongating the slot for more belt tensioning was an easy task, but the one mounting spacer for the dynamo was found cracked. Still not a real big deal to replace. Another task done.

The Oil Leak
I was now down to the engine block, so some major cleaning was in order. There had been a small oil leak going on somewhere, and all the cooling air going through the cowl sure had a way of spreading it everywhere, with a few landings on grass strips here and there helping to mix in some road dirt. It’s not hard to imagine all the work to get into all the nooks and crannies for the cleaning of an air-cooled engine. After getting this cleaned up I decided to look for the leak. There was nothing obvious, so I tightened up bolts and covers, followed by removing the top oil cover and replacing that gasket. And don’t forget another trip to the powder-coat shop in between. Now the flex plate and top oil cover were coated. I also replaced the oil pan gasket for good measure, but it seemed like it was sealed well when I took it off.

The Firewall
With the engine removed, the firewall and all the things left hanging there were easy to check on. While cleaning up things there I noticed that the fire sleeve on the fuel lines was loaded with oil because I had never thought to seal the ends. Remember the oil leak that I couldn’t find? I now thought that some of it was old oil that was in the fire sleeve, and when the engine compartment heated up, some of it would drip out if for no other reason than to drive me nuts. I replaced all of the fire sleeve on the fuel lines and sealed the ends this time. While the fuel lines and gascolator were off, I was able to polish up the stainless-steel firewall.

The firewall on a KR is made from 1/4-inch plywood with a layer of Fiberfrax over it, protected by a stainless-steel sheet covering it all. With the oil leaks over 5 years, I noticed that the oil worked its way into the cockpit. With the engine mount off and a good deal of the other items either off or easily removed, I decided to try a little trick. For each screw or bolt penetration into or through the firewall, I put a dab of high-temp RTV (room temperature vulcanizing) silicone in the hole and then reinstalled the part. The engine mount has the Fiberfrax and stainless sheet trimmed around their respective mounting location, so the mount is in direct contact with solid backing. Besides the bolt holes, I ran a bead of the RTV around the perimeter of the firewall edges so that the Fiberfrax wouldn’t become saturated with oil or anything else.
My next focus was wiring. As the disassembly process was happening, I would notice a connector here and there that had been twisted or otherwise deformed at some point in time. Also the ground cable and grounding strap to the engine block had seen better days. I replaced with new, the ground cable from battery to the engine block. The starter cable received one new terminal end. Also the braided ground-straps that jump from engine block to engine mount and bond the entire system to the plane were replaced with new.

Several terminal ends were replaced on signal wiring, and those wires were also rerouted and bundled and mounted in a more appealing method. Many of the wires in the engine compartment had been add-on devices over the years, such as O2 sensors, FloScan, and manifold pressure to name a few. Remember those red items I had painted or powder coated? Now I noticed that I had used all different colors of zip ties over the years, so as I rebundled and rerouted the wires, all zip ties were changed to red and spaced for more appeal (at least to me).

Intake Manifold
During the cleaning process, I had to disassemble the intake manifold. This was where I discovered something that concerned me most. First, though, a little background. This past fall, while coming home from the National KR Gathering, I was chasing a weather front from Kentucky to Pennsylvania. I had to stop several times to wait for it to move on. The airports that I landed at along the way didn’t have fuel available until the last one, but it had just closed for the day literally a couple minutes before I got there. I found someone that had a couple gas cans and would take me into town. I put about 4 gallons of Sunoco 93 in each wing tank and transferred it to the header tank which had about 3 to 4 gallons of avgas left in it.

I had run auto fuel before and had no problem, so it wasn’t a concern. The short version of the rest of this story is that several days later, just before going for a pleasure flight, I had an issue with the throttle sticking. I grounded the plane until the problem was resolved. I replaced the throttle cable, and that seemed to solve the problem. But I continued to investigate. I removed the AeroCarb and found a brownish tarnish on the slide. To my dismay this color matched the E-Z Poxy color that the header tank is made from. I immediately drained the remaining 7.5 gallons from the header tank and examined the inside. I really couldn’t find any deterioration in the tank nor discoloration in the fuel drained out. Now I found the brown coating on the interior of all of the intake tubes.

Looking inside the T-connector of Joe’s intake system, we can see the brown goo congealed along the runners.

Whatever it was, it had never been there before and appeared to condense out of the fuel mixture in the intake tubes, as there were actual dried puddles on the horizontal runs of tubes. The sticky brown gunk easily was cleaned up with lacquer thinner. All the tubes were cleaned, and the carb was cleaned. The gascolator had a sediment buildup on the filter. Avgas was put back in the tank, and after another 30 to 35 hours of flight time, there were no issues.

Fuel Tank
This takes me back to the header tank again. That fuel gunk was really bothering me. One of my hangarmates had a borescope, but I couldn’t tell much with it except that the inside top of the tank was still glossy and the bottom was a bit dull-looking. Sticking a screwdriver down the fuel fill hole, I was able to scrape a little bit of gunk on the blade. So I cut three giant holes in the top of the tank. The bottom and about halfway up the sides, I could scrape with my fingernail, leaving a white line and getting a little bit under my nail. The top of the tank was still shiny and hard just like new.

So I sanded the entire bottom and sides and then cleaned it up with lacquer thinner. Lacquer thinner did a good job cleaning the other parts, so I figured that was a good test. I scrubbed the inside with the thinner until there was no more brown getting on the rags. Once it was dry, I coated the whole inside (except the top) with fresh E-Z Poxy.

While I was at it, I cut the filler neck shorter where it enters the tank and cleaned up the fuel sender that had been giving trouble—no doubt a result of the gunk on it. The access holes were patched, and I gave the tank a week to cure with heat lamps on it. An Internet search revealed no known problems with E-Z Poxy and any fuels, so I have no idea what caused this, except the one use of the Sunoco 93 which most certainly had ethanol in it and who knows what else. Caveat emptor. (Let the buyer beware!)

Air Filter
While I was sitting on the floor just staring at the front of the engine (after putting everything back together), I decided it really was time to get serious about the air filter arrangement. The hangarmate said he might have something about the right size from a Cessna and brought down a nice-sized flat filter made by Fram. After sitting there a few minutes I realized that I had been confining the design to parts I either had or could easily get. After a couple more minutes I saw the solution so clear. All I had to do was reroute my cabin heat and intake heat lines and all would fit. An added benefit was the clearing of some clutter, cleaning up some space for exit-cooling air from the cowl.

I started building the air-box prototype by using some rough overall measurements and a few locating dimensions for the carb and available space for the 2-inch carb heat duct. It was fabricated out of a 10-inch-wide coil of aluminum roof flashing. This was thin, light, and easy to work and rework. After a rough box of sorts was crafted along with the corresponding holes for the carb and heat duct, a trail fit was made (in order to find out what other interferences there might be). This went well as only some minor adjustment in the box size and shape was necessary. The two holes were adjusted slightly, and the flapper for the heat shutoff was trail-fitted.

Another trail fit showed things clearing all areas, so a final version was made of the same flashing stock and pop-riveted together. The entire box was then glassed over the outside, and the two holes had glass tubes formed as receptacles for the carb throat and the 2-inch SCAT tube. After curing (post cured in the oven at 150 degrees), I trimmed it up, sanded it some, and painted it red to match the rest of the engine parts. The filter was fitted and retainers made and installed. The whole assembly weighs about 1.5 pounds.

Left side
Larger view
Larger view
Larger view

The one mistake made was the direction of the flapper lever. It’s oriented so that the cable had to be run past and then back again to operate in the pull-for-heat on position. I thought than maybe I would fix it sometime in the future, but it bothered me enough that I went ahead and cut the lever off, turned it around, and welded it back in place. Then the cable was shortened, and the whole operation of carb heat was cleaned up neatly.

The other upside of reworking the air filter box was that I will be able to change the bottom profile of the cowl to a more streamlined and otherwise more aesthetic shape. That also will wait for a later date and warmer weather.

The last few details in the final assembly were to clean up the routing of the spark plug wires; regap and reinstall the plugs and temperature senders; tie-wrap the last of the SCAT tubing into place; and finally, connect the battery. There was another detail from inside the cockpit that needed addressing while the header fuel tank was empty: The past year or so I had noticed the smell of fuel when the plane would sit with the canopy closed. There was never a drip on the floor but a little dampness at one of the fittings coming from the bottom of the header tank. I disassembled the fittings and shutoff valve, cleaned the threads on the fittings, and sealed and reassembled them. At the fitting that seemed to be the problem, I was able to get one more turn out of it that I was probably afraid to do before. The fuel tank was refilled and checked for leaks. Got it!

Starting ’Er Up!
The big moment came at last. I pulled the plane out into the sunlight. Put the chocks under the wheels and hopped in. I meticulously went through the start-up procedures and then turned the key. And, and, and…nothing. Dang (not my exact words). Either I forgot a wire somewhere or the battery was dead. I did a couple more tries, and it clicked and did a partial turnover with some grinding noises. So the battery was the culprit. I settled on letting it charge in the hangar overnight and trying again the next day.

The following day, with a fully charged battery, I pulled the plane out and went through the whole setup and start-up procedure—nothing but a grinding noise. Geez! I pulled the coil wire and tried turning the starter over again and got nothing. After some more fooling and checking, I pulled the starter and took it back to the parts store. They put the starter on their testing machine and they got nothing. I had gotten a bad, new starter. They replaced it as a warranty exchange on the spot.

The next day or so, I reinstalled the second new starter and went through all the same steps to start ’er up again. This time the starter worked to the point that it kicked in and spun, but at the same time I heard a terrible grinding noise. I switched off right away and rechecked the engagement location of the starter gear and the flex plate. After checking it over again I noticed that I really hadn’t looked the flex plate over very well after the first starter. The flex plate was now showing considerable wear. To get this exchanged, the engine was going to have to be pulled again. There went next weekend!

One More Weekend, and Another
Over the next few days, I located a new flex plate and another used starter to use for donor parts. Over the weekend, the engine was pulled and the flex plate replaced (and painted red). The starter gear was replaced from the donor starter as there was visible wear on the gear from the grinding. After reinstalling the starter on the engine it was checked carefully for engagement with the flex plate. There seemed to be a slight out-of-square mounting of the starter. The lower mounting bracket looked like it was the culprit. The bracket was reformed to align with the flex plate. This still didn’t fully square up the alignment. Some more studying revealed that the top mounting bracket was also bent slightly. This was straightened and the starter remounted, again. This time it aligned perfectly and the gear engagement was great.

The engine was reinstalled over the next weekend. All the hoses, clamps, wire-ties and whatever else that had been disconnected were all put back into place to be airworthy. The rollout and next start-up attempt would have to wait another day as daylight ran out for the weekend. Monday was a beautiful spring day here in the Northeast with the first temperatures in the upper 70s. After work, I did the rollout and preflight all over again. This time I removed the distributor coil wire and did a test turnover of the starter. It all seemed to work fine. I took one more look around mostly to make sure there were no tools left in the engine compartment, then hopped in. It only took two blades and she fired right up! And, oh, what a sweet sound after six weeks of fooling around.

I let it warm up and did a timing check at idle rpm. It was right at 15 degrees. With the distributor advance of 16 degrees, it should be right at 31 degrees advance at high rpm once the distributor’s centrifugal advance kicks in. With no one around to operate the controls for me at the moment, this would have to suffice for now.

With the cowl still off, I took her out to the taxiway and did a couple fast walking speed runs back each way. So far, so good, so I took it on the runway for a couple high-speed runs. These went well, too, with the engine coming to life easily and smoothly. I taxied back to the hangar, buttoned up the cowl, and put her away with the plan of taking the first new flight in the early morning.

Flight Time!
The next morning dawned calm and clear, and for a change, the plan was coming together. I did about a 10-minute preheat to get the oil temps in the 60s and pulled her out again. She fired right up and purred like she was ready. I didn’t have much time before work that morning, so it was going to be a quick flight, maybe only around the pattern just to say that I could fly again. The acceleration down the runway seemed better than I remembered, and we were quickly airborne. The climb-out was uneventful and the numbers all looked good. So I turned south, exited the pattern at 1,500 feet, and just let her flat out with full throttle.

The rpm kept climbing until leveling out at about 3,410. This was about 60 to 70 rpm higher than I had normally achieved. I continued straight and level for 8 to 10 miles and did a 180 back toward home. Everything settled out the same after the turn back, so I entered the numbers into the aviation calculator and got a true airspeed of 179.4 mph. Now I was getting happy because this was 2 ½ miles an hour faster than I’d ever done before at low altitude. I entered the pattern and had a nice landing. The only thing that I noticed in the pattern was that the throttle seemed to have a little sticky spot. I had to leave for work, so this issue would have to wait until evening.

The AeroCarb
I did as I planned and looked into the sticky throttle issue. And again, it was one of those things that just took on a life of its own. The more I worked on it, the stickier it got. It would work perfectly until the engine started, and it got to the point that I could only close it but not open it. This was a very early version of AeroCarb. I took it apart and cleaned it again, and it seemed like the Teflon coating on the slide had worn off. I ordered a new slide and received it in a couple days. So all excited to have the cure in hand, I took the carb off and tore it apart again. I tried to insert the new slide to no avail. It was too big in the one direction by about 0.01 inch. I contacted the factory again, and this time they just said we want your carb back. At this point, what’s another week? It was shipped back to them. They were good to their word and turned it around the same day, replacing the main body and slide with an updated version.

The following week, I reinstalled the rebuilt AeroCarb and went through the setup procedures. This took several hours which was much longer than I had anticipated, but I was pretty certain that she would start up without a hitch. On Saturday morning I went over everything again and hauled her out without the cowl on again. She fired up right away and idled smoothly, although a little low on the rpm. The mixture gauge showed a little on the rich side. I did a couple taxi runs and came back and adjusted the idle up a little and the mixture a little leaner. Everything seemed to be a go for a test flight. I buttoned her up and headed out.

The acceleration seemed much better than I remembered from earlier in the year, and the climb was very strong. I took a couple laps around the pattern at a higher altitude just to be safe. After becoming a little bit secure in my mind, I headed out to do some climbs and extended speed runs at different altitudes. The climbs and speed runs still confirmed the initial results from the previous week. I was getting a couple miles an hour faster at the low altitude, and at 7,500 feet I was getting a true airspeed of 171 mph. The rpm indeed rose higher by at least 60 which was really where the extra speed was coming from. The fuel burn was up from former testing by a couple tenths, too—now at about 8.5 gallons/hour down low and around 7.6 up high.

The test flight lasted about 1.5 hours and really went well with nothing coming even close to being out of parameters. The carb needs a little more idle again, and the mixture needs to be slightly leaner. I also still need to do a full-throttle timing check for verification. Everything else is a go from starting with some painting and tightening the alternator belt to the carb and starter trials and tribulations. It’s all behind me, and I feel great about the condition of my plane for this year’s flying season. I have since been able to take my youngest son for a couple flights again and enjoyed short solos almost daily the past couple weeks.
If there’s any small moral to the story, I would say never get discouraged. The path that was presented to me was one thing after another but all necessary for safety’s sake. For everything I had to repair, I have less than $200 invested, and I certainly feel it was all worth it. I didn’t even miss very many good flying days.

 Blue skies, folks!


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