Help me tame the monster!

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In wrapping up my glider project of 20 years or so, and in my effort to remain true to the plans, I have created a squeak monster.
First glider info. Prue Super Standard sailplane. 15 meter span, all metal monocoque stressed skin construction. The aileron control push/pull rods are 6061T6 3/4" in diameter and are about 17 feet in length. The supports for the control rods, as they run through the wing are made from linen micarta straight out of the early 60's. The supports with 1" diameter holes were riveted to the ribs during initial construction. When the control rods are moved it is squeak city. So much that I have pulled the drawings out to prove that this method of construction was called out. I had lubricated the rods and supports with Aeroshell grease during the initial construction but it didn't make very much difference. Final inspection this late July, she hasn't flown yet. Any ideas or suggestions are welcome. It may just be earplugs....
 

Dan Thomas

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In wrapping up my glider project of 20 years or so, and in my effort to remain true to the plans, I have created a squeak monster.
First glider info. Prue Super Standard sailplane. 15 meter span, all metal monocoque stressed skin construction. The aileron control push/pull rods are 6061T6 3/4" in diameter and are about 17 feet in length. The supports for the control rods, as they run through the wing are made from linen micarta straight out of the early 60's. The supports with 1" diameter holes were riveted to the ribs during initial construction. When the control rods are moved it is squeak city. So much that I have pulled the drawings out to prove that this method of construction was called out. I had lubricated the rods and supports with Aeroshell grease during the initial construction but it didn't make very much difference. Final inspection this late July, she hasn't flown yet. Any ideas or suggestions are welcome. It may just be earplugs....
Grease attracts dust that abrades everthing and turns to sludge so controls get sticky. Clean it all off, even inside the guides, and use dry silicone spray lube.
 

TFF

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My friends Mooney squeaked on the ground. Couldn’t tell in the air. There had been grease applied multiple times. which lasts minutes. Without adding rollers, rosin up the bow and play a tune. Fly your plane. Send us pictures.
 

Dan Thomas

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Replace the micarta with Delrin (acetal) or a Teflon blend.
UHMW. It's softer. Ultra high molecular weight polyethylene. Commonly used as abrasion-resistant sheet in grain handling equipment. Used as bearing material in lots of stuff. Some kitchen cutting boards are made of it.

I used the dry silicone spray (goes on wet) in Cessna control columns. The control wheel (what many mistakenly call the yoke) is on a shaft that travels in and out of the panel in a nylon bearing. Micarta in old airplanes. People grab that shaft now and again and leave skin oils on it. Eventually, a layer of sludge builds up in that bearing and when you move the elevator up and down during inspections or preflight, you hear and feel a chattering and some drag. I cleaned all that stuff off the shaft and out of the bearing. Sometimes had to cut a strip of fine sandpaper and wrap it partway around that shaft and run the shaft and sandpaper in and out, scrubbing the inside of the bearing clean. Brake cleaner works for much of it, but the sandpaper will be necessary for the big buildups. Then the silicone gets dribbled on the shaft and it's worked in and out and around, and the owners exclaim how nicely the airplane flies after that.

Graphite doesn't stay put in a place like that. It's ok for Cessna's aileron piano hinges, but getting it into the hinge is a pain. I mixed it with some brake cleaner and dripped it on the hinge, where is immediately flowed into the hinge, taking the graphite with it. The cleaner dried quickly, leaving the graphite where it needed to be.

Paraffin is another handy dry lube. Rub it on. Works for door latches and stuff. Rub it on the underside of Cessna seat rail flanges, where the roller housing drags and galls up and wears.
 
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raytol

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Cut an access hole in the wings and install an upper and lower nylon roller with ball bearing racers. Glasflugel solved the squeeking problem back in the 70's. Also, 17ft is too long for a single control rod in the wings but you may get away with it as the wings are stiff.
 

proppastie

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My friends Mooney
on my Mooney I use spray lithium grease using a straw ....small 1/8 hole will be all you need if you know where the bearing blocks are....no squeak here.
 

TFF

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I’m not opposed to pulling the panel, it’s just the nature of the beast of this type of system that it makes noise.
 

Dan Thomas

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Wings already closed and graphite and aluminum is a big corrosion no no.
There has been a lot of back-and-forth over that. Not sure if it's true or not. Cessna specs graphite lube on their aluminum piano hinges on the ailerons, and I never once saw any resultant corrosion. All I ever saw was wear, and some of that was due to people using greases or oils instead of the graphite. Or using nothing at all. The hinge halves and pin are all aluminum.

I think graphite on aluminum, if there's heat involved, could be a bad thing. It can be a bad thing on steels; the metal absorbs the carbon, getting harder and more brittle in the process. And yet, Champion recommends their anti-seize on sparkplugs, and it's a graphite in a light solvent. The plugs go into the aluminum cylinder heads. Other anti-seizes such as Never-Seize and Copper-Coat contain graphite, and are used all the time on plugs.

Graphite's problem is staying put without any oils or greases. The dry silicone spray stays better, but not forever. It's so thin it wears off soon.

If there's squeaking, I'd be looking for the reason. There's obviously something flexing to do that, and it might be the wing rib or whatever else the bushing is fastened to. Better to add a bit of a stiffener, maybe.
 

Dan Thomas

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I was just going to say that. The plans phenolic aileron torque tube bearings wore out at 600 hours in my Long EZ so I made new ones out of Delrin. No wear noted 1,400 hours later.
Can't remember if it was this forum or POA hat I mentioned that I was restoring an old ten-horse outboard motor. These old things (1963) didn't use tapered roller bearings in the propshaft gearcase; they used bronze bearings (bushings). The bushings had worn out because someone had tried to fix a leaking oil seal by putting grease in the case instead. Grease doesn't flow, especially when that leg is in cold water, and the bearings got dry. Ugh.

Now, I machined thousands of bronze bushings for compressor crankshaft bearings and wrist pin bushings, up until 30 years ago. So I went looking for some C93200 bronze.. Couldn't find anyone that carried any at all. Only major warehouses, and I'd have to buy 12 feet of it, or a shorter bit from some online outfit that charged far too much and added cutting fees to that, too. Would have cost way more than I paid for the motor. So I made some bushings from Delrin scraps I had here. Put them in, ran the motor last summer for several days while fishing. Took the gearcase apart to check them this spring, and found no wear at all on the Delrin.
 
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Fiberglassworker

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Depending on how much you want to rework your glider, Schleicher came up with a good solution to this 40 years ago. Their solution was to replace the Delrin bushings with triple ball bearings, each bearing set at 120 degrees to the next radially with a pitch diameter the size of the pushrod, they still use this system today.
 

Dan Thomas

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Depending on how much you want to rework your glider, Schleicher came up with a good solution to this 40 years ago. Their solution was to replace the Delrin bushings with triple ball bearings, each bearing set at 120 degrees to the next radially with a pitch diameter the size of the pushrod, they still use this system today.
You find that in the Cessna 210 and a few other models. They're carrying the control wheel shafts. They're a tiny bearing with a nylon wheel molded onto them, and the shaft runs in and out and rotates in them, the rotation being a sliding action across the wheel. Vibration makes the shaft rumble in those bearings, and as the nylon ages and gets brittle, it breaks off and leaves the steel bearing rattling on the shaft. One more reason to pay for a good propeller dynamic balance job.
 
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