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Winter Work

By Joe Horton, joe.kr2s.builder@juno.com

Horton
Photo courtesy Mark Langford

I took N357CJ (my Corvair-powered KR-2S) home over the Thanksgiving holiday. I had flown her for just over four years and over 450 hours. I’ve been a little more than rough on her, and I was certain that she needed some good R&R and a little tender care.

When I got her comfortably resting in the heated workshop, I sat down and started a list of things that needed to be done and a list of items I wanted to do. Keep in mind that those two don’t always have the same priority. Ultimately, I was very surprised at the size of the list as it contained simple things such as just checking, tightening, and adjusting, and some bodywork to clean her up aerodynamically. I knew all along that, if she stayed at the airport, I would never do some of the stuff, so I was forced to take her apart and bring her home.

I didn’t get started doing much until late December but have worked on her steadily ever since. Some days, I would do something simple such as adjusting the landing and taxi lights because I now know my landing attitude; when I installed them, it was only a guess. Other times, I just bit into projects that I dreaded to no end.

Flaps
One of the major items was my manual split flap actuator. I was getting a lot of reflex of the flaps; I was concerned that it was from abusive wear such as taking off and for the first 20 minutes or so trying to figure out why I could only manage 155 mph instead of 170 mph. I started by testing and studying each component. In the end, I cut into the bottom of the stub wings and removed the complete system. Doing so, I discovered a couple fatigue cracks in some aluminum parts and excessive flex in others. The original choice of materials from which I chose to build my system turned out to be the true mistake. The materials were picked with weight-savings being the primary consideration, but now I’ve changed the torque tube and the associated linkage from aluminum to steel. I also had to reinforce the actual flap handle as there was the ability for it to twist slightly from the resistance of the flaps.

Horton

The result at this point is still untested, but the new system is very stiff. I also changed the system from two positions instead of the original three, now 25 degrees and 50 degrees relative to the bottom of the wing. I think this will be a considerable improvement.

Instrument Panel
I also decided that I may want or need to meet the ability to fly at night. That meant getting my panel lighted as the plane already has all the required exterior lights. I found a set of peel-and-stick red light-emitting-diode (LED) strip lights at the local AutoZone that fit really well on the underside of my glare shield. I wired another switch and breaker into the panel and tied in all the other instruments that had internal lights. Just for the record, I rewired the LED strip with Tefzel.

Horton

While working in the panel, I redid some of the wire bundles and removed some of the “spaghetti” that had developed over the past few years of changing and upgrading instruments. Also while I was in the back, I wired in the Grand Rapids engine instrument system to a laptop connection (serial out) and also installed a carburetor temperature probe to round out the information that I can now save and retrieve for future reference. I wired my Lowrance 1000 GPS into the Dynon D10A. I also tried adding the remote compass and an outside air temperature to the D10A, but there’s something not right inside of the D10A; I’ll have to return it for service. Slaving the GPS to the D10A was really cool, though, and gives another layer of flight information that, in all honesty, I probably didn’t have the knowledge to process before. I’m really looking forward to using it.

Horton
Photo courtesy Mark Langford

Canopy
I also attacked my forward-opening canopy latch, which always seemed tight on the ground, but in the air it flexed open with enough space to suck out my shirt sleeve. This has to be a tremendous amount of drag. I changed to a different style of latch and reset its limits so that it pulls down with a little extra pressure—I think I finally have that cured. But on the other side of the equation, if air was sucking my sleeve through the gap, all that air had to come from somewhere. I’m pretty sure that the only hole in my fuselage is where the elevator spar passes through the vertical stabilizer. This was also in evidence in the winter when there was a pile of cold air coming up in the control stick holes in the seats which is open to the rear of the fuselage. So for now I closed this hole with some sponge foam just to stop the source of air from entering the cockpit. I really believe that this condition was costing several knots. The next flight will tell.

Horton
The 3100-cc six-cylinder air-cooled, direct-drive Corvair engine conversion (modified from a stock 2700-cc engine) has proved to be a great match for the KR-2. Since this photo was shot, Joe has installed the “fifth bearing” used to take propeller loads off the crank. Photo courtesy Mark Langford

Engine
Next was the engine compartment. I’m not done yet, but so far I’ve taken apart the carb, disassembled the intake tubes, removed the rubber couplers, and replaced them with new gas filler neck tubing. (Note to self: The service life of no-hub couplings from Sears hardware is about 400 hours—just bite the bullet and use the right stuff!) I’m in the process of rebuilding and replacing all the baffles. I replaced the plugs and O2 sensors which I installed on each exhaust header last summer. Other items: changed the oil and filter, rebuilt and reinstalled the carb heat box, and checked belts and wiring.

Airframe
I also discovered more small items here and there that just needed tightening or adjusting. This was a little surprising to me, as during previous annual condition inspections I checked all the little spots of fingernail polish that I put on every nut or screw during building to indicate 1)I had in fact set that particular connection to torque, and 2) that in the future it had not moved or changed. Apparently this is not a valid check for a wood structure as wood can shrink and grow with humidity, affecting the clamping pressures of bolts that run through it—just as we all know about wood propellers. I’m now convinced that every bolt or screw into wood needs to be physically checked. I found several brackets that mount the cowl as well as the canopy, which were just slightly loose.
 
I also worked on the nose gear that I continue to abuse regularly through use of some pretty rough runways, as well as some pretty bad grass fields. I had to replace a small backer for the bolts to the firewall and all new bolts while I was at it. That change started just because they were slightly loose.

I cleaned and shampooed the interior, but I haven’t gotten to any of the bodywork that needs to be done. Not likely to get done now, either. I plan on returning N357CJ to the airport this week to depart for a trip to Florida.

Horton

Well, gotta run! I’m wasting work time and I have to get the O2 bottle filled today. N357CJ will not be the prettiest face on the block, but I feel like I have improved her safety.

 
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