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Old 04-17-2018, 10:35 PM
RepmikeBrown RepmikeBrown is offline
Join Date: Oct 2012
Location: Tahlequah , Ok
Posts: 175
Default Culprit

Big milestone today. I finished installing wings, plumbing, wiring and checked all of my aileron up and down movements. The stick movement seemed a little heavy left and right but ok forward and aft. I probably wouldn?t have ever second guessed the heaviness had there not been another RV4 in the hanger next to me. It?s movements were effortless, but I did have the servos connected from an auto pilot installed. I thought maybe this added the extra drag in the controls. Not satisfied I disconnected the aileron servo and still had the heavy stick both left and right. I start with left and right aileron bushings/washers, any possible rubbing of close parts. Moved on to the aileron push rods checking all rod end bearings and washers. Next the bell crank and then the large push rod tubes all moving freely I install them back and still heavy left /right movement on stick. I examine the stick control for binding or interference, and then finally removed the heim bearings for inspection. I?m down 2 days so far, but finally found the culprit. The rear heim bearing has been damaged ever so slightly. The small crease on the brass
has also creased the interior of the housing race causing the bearing to bind. I just wished I?d started looking from that point first. Lesson learned.
RV4 Built/flying
Mike Brown
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Old 04-18-2018, 06:25 AM
Michael Henning Michael Henning is offline
Join Date: Jun 2011
Location: Nashua, NH
Posts: 546

It?s always the last thing you check🤔
RV-4 #2750
WW150C Prop
1018 lbs
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Old 04-18-2018, 06:43 AM
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snopercod snopercod is offline
Join Date: Aug 2016
Location: Asheville, NC
Posts: 2,122

We pay $60 for those rod ends because of the excellent quality control /sarc
(2020 dues paid)
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Old 04-18-2018, 07:58 AM
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Sam Buchanan Sam Buchanan is offline
been here awhile
Join Date: Dec 2004
Location: North Alabama
Posts: 4,466

That type of damage is often caused by careless use of a wrench to tighten the bearing. Good catch!
Sam Buchanan

Last edited by Sam Buchanan : 04-18-2018 at 08:26 AM.
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Old 04-18-2018, 08:17 AM
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DanH DanH is offline
Join Date: Oct 2005
Location: 08A
Posts: 10,356

Whatever the cause, kudos to Mike for chasing it down, and not blowing off the control drag, as we see so many do.
Dan Horton
Barrett IO-390
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Old 04-18-2018, 08:52 AM
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AlexPeterson AlexPeterson is offline
Join Date: Sep 2005
Location: Ottertail, MN
Posts: 2,461

Mike, nice catch. Could that damage have been from the two rod ends on that particular pushrod being clocked with a "twist", causing binding? It almost looks like a washer was grinding into the brass.
Alex Peterson
RV6A N66AP 1750+ hours
KADC, Wadena, MN
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Old 04-18-2018, 09:18 AM
RepmikeBrown RepmikeBrown is offline
Join Date: Oct 2012
Location: Tahlequah , Ok
Posts: 175
Default Twist

The only thing I can think is yes, plus over torquing which caused the damage
RV4 Built/flying
Mike Brown
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Old 04-19-2018, 09:23 AM
EXflyer EXflyer is offline
Join Date: Jan 2016
Location: Chiloquin OR
Posts: 94

Originally Posted by RepmikeBrown View Post
The only thing I can think is yes, plus over torquing which caused the damage
Over torque would not cause this damage as there should be nothing crushing when doing so. A bolt could fail due to that this was cased by one of two things, rod end bearing frozen causing it not to center or the two ends not being aligned causing a washer to extrude the brass. Due to the damage I think that replacement of both ends would be in order not just the one with damage as there was a reason it stuck.
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