Archive

Archive for January, 2011

Gear Camber adjustment and Cowling Plugs

Here’s a comparison shot of the old axle and axle nut along with the new camber shims. I really like the looks of the Grove aluminum axle and axle nut. It should make installing the wheelpants slightly easier, too.

Here’s the axle, tire, wheel and shims installed. The tire almost looks like it’s tipping inward. I think this is just because there’s no weight on the wheels. I measured the camber at 9 degrees and this shim is 7 degrees. It almost looks like the wheel is now toe’d inward. I’ll have to check the alignment again before I fly it.

I’m really impressed with this axle nut made by the Grove gear leg people out in California. The holes line up perfectly for the cotter pin to slide through the axle.

This is the second step in the fabrication of my cowling inlet covers. In this step I laid out the plugs facedown on a plastic sheet covered with wax. I then glassed inside the plugs so that I wouldn’t increase the outside dimensions of the plugs. They fit the cowl inlets perfectly now. I think a layer of felt will make them fit nice and snug.


Long time, no posts…

Yes, it’s been a while since I’ve posted anything. I haven’t been in the mood to fly much now that we’re into the cold weather season. As of today (January 28, 2011), I have 61.4 hours on the plane since putting it back into service in June of 2010.

I’m still having issues with my comm radio so as part of the troubleshooting process, I made up this little harness. It breaks out the push-to-talk circuit and allows me to verify that my PTT is not the source of my radio problems. It was a bit of a pain to fabricate this harness, but it was still better than breaking apart my real harness to isolate the PTT. Bummer. the PTT was verified to NOT be the source of the problem. The antenna is the next step in the troubleshooting process.

Another nagging little issue I’d like to resolve is that I seem to have a twist in my airframe. My left aileron must be deflected upward slightly (forcing the left wing down) to maintain wings-level flight. A guy I worked with suggested that my elevator trim tab located on my right elevator could cause a twist. I bent up a fixed trim tab with the same deflection as I normally carry in level flight. I then taped this trim tab to the left elevator and left the trim tab on the right elevator in trail. Bummer. Still didn’t fix the problem. Keep looking…

A friend of mine has a Bridgeport mill. He offered to help me make some shims for my landing gear to adjust the camber. We fabricated 2 shims. One of them is 5 degrees and one is 7 degrees. I haven’t taken time to install them yet, but will probably do so within the next week or so. Frequent readers might remember that I had planned to machine the bases of some new axles I recently purchased from Grove. After I did the math and figured out how much material I’d have to remove from the gear legs, I decided it would be best to have external, separate shims.

This little guy almost ruined my whole darned day earlier this week. This gasket goes between the housing for my oil screen and the engine case, itself. If you click on the picture to enlarge it, you’ll notice that there’s a tear in the gasket… Well, the other day I was taxiing out for takeoff and my low oil pressure light came on. Argggh!. The pressure gauge confirmed the light so I shut the engine down immediately. I got out of the plane right there in the middle of the taxiway to see if I could see an obvious problem. The problem was VERY obvious!
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I left a trail of oil approximately 1000 feet long between my hangar and where I stopped. With the help of a friend, we dragged the plane back to my hangar and found part of this gasket poking out from between the case and the oil screen housing.
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A half-roll of paper towels along with copious quantities of Stoddard solvent later, I removed the oil screen housing and found this torn gasket. Not good. Lucky for me, we’ve got Firewall Forward located on the field. Those guys are really good to all us locals. They spend a half-hour looking through their boxes of gaskets trying to find the exact part and in the end ended up just giving me some gasket material to make a new one.
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After having pumped all but 2 quarts of oil out of the sump, I decided I may as well go ahead and do an oil change. It had already been 20 hours since the last oil change, so I wasn’t too far away from my 25 hour interval anyway. Happy to find nothing in the oil screen and with the new gasket fabricated and installed, I left the plane on Wednesday night sitting with fresh oil and ready for a leak-check run-up the next day.
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The leak-check was dry as a bone so I went and flew it for 0.8 hours on the Hobbs today. Came back and it was completely dry inside. I’m really fortunate that this incident didn’t ruin my engine, or worse, cause an off-field landing. If that little gasket had held out 10-15 minutes longer, I would have been airborne and might be writing a very different report… or none at all, if things really went poorly.
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The moral to this story (i.e. the lesson I learned) is that no leak, no matter how small, should be ignored. I’d been chasing a leak from day one on this engine. I thought it was coming from the oil screen or the oil temperature bulb. I hockey-puckied the heck out of the threads and replaced the copper crush washers several times trying to fix the leak. It seemed to go away for a time, but had come back within the last 5 hours or so. I was putting off dealing with it because I’m planning a re-work of my oil system anyway when I install the spin-on oil filter and re-locate my oil cooler. Putting it off almost cost me dearly.

Since the upper and lower cowling were removed anyway, I decided to tackle a little project I’ve had in mind for several months. I’d like to fabricate plugs for the inlets on the front of my cowling. I’d like to make fiberglass plugs so that they fit nice and look nice. I taped off and waxed the openings in preparation for the fiberglass and resin.

These are some of my fiberglass supplies. The cloth was cut on the bias so that it will lay down better around all the curves. The roll of white is shelf paper. I find that it’s sticky enough to adhere to the part, but not so stick as to leave residue. The greenish roll is just just masking paper. The white tub is Partall paste wax that I’ll use as a parting agent.

I’ve laid up at least 2 layers of 6-ounce cloth in this picture. I have a tendency to make my fiberglass parts way too thick so I decided to start with 2 layers and add another later if it’s necessary. You’ll notice I didn’t cover the smiley inlet with the shelf paper. Instead, I relied on a few good coats of Rejex polish and a few coats of the paste wax parting agent. This approach almost bit me in the fanny. I had to use a little elbow grease to get all the epoxy off the paint. Lesson learned for next time!

Nothing was curing too quickly with our 40 degree overnight temperatures so I took advantage of the cured-to-tacky-but-not-rigid state of cure and rough-trimmed the plugs. Of course these won’t be very effective as plugs in this state so I plan to cover the openings with additional fiberglass. I plan to cover the backside of the plugs with felt so that they won’t scratch the cowling when I take them in and out. I know a lot of metal airplane builders hate working with fiberglass, but I kinda like little projects like this. If nothing else, it’ll be nice to have these plugs ready to go for this year’s flying season!
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I had a visitor today. A gentleman from Australia is considering building a Midget Mustang. He’s 4-5 inches taller than me so he was interested in trying the plane on for size. Much to my surprise, he actually fit without much trouble. His legs bumped up against the fuselage fuel tank, and the headroom was a little tight, but workable. If he puts the fuel in the wings to get rid of the fuselage tank and if he goes with the M1A slider canopy, he’ll fit just fine.
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Sorry it’s been so long since my last update. I’ve recently decided to stop posting to a different site and concentrate more effort on maintaining this blog on a more regular basis. I’ll try for weekly updates even if there’s nothing going on.
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Happy flying. Rod.