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Old Aug 10, 2011, 09:49 AM
Lance
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United States, GA, Alpharetta
Joined Mar 2008
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My H9 P-47 retracts are making some sounds

I've got this H9 P-47 with the OEM mechanical retracts. I had to put a new 791 servo in, the Futaba didn't have enough torque. When they go up, there's a 'creaking' noise. It sounds like something in the wood of the plane (a bulkhead, etc). I don't think it's affecting anything but I can't look inside the wing during the up retract operation to visually be able to diagnose the stress.

Anyone else ever see this?

Retracts on a Hangar 9 P-47 60 (0 min 29 sec)
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Old Aug 10, 2011, 11:51 AM
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It could be a bulk head..could also be vibration in the push rods..it also doesn't look like your retracts are going all the way up?

I'd also pull the retracts out of the wing and check to see if possibly moving parts are rubbing against wood..it sounds like somethimes rubbing across a bulkhead or former when the retract is under load...if thats the case you should be able to see gouges in the wood where its hitting and a little dremel action with a drum sander will clearance it just fine..rubbing and gouging the wood can lead to binding and eventual breakage..better to be safe than sorry

Troy
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Old Aug 10, 2011, 03:34 PM
Lance
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United States, GA, Alpharetta
Joined Mar 2008
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Thanks for the info. I forgot to mention it doesn't make that sound when the wing is inverted. So it must be gravity-related and you can't hear it in the video but it sounds like it's straining when it makes that noise. I'll pull the gear out tonight and look for scuffs.
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Old Aug 10, 2011, 03:57 PM
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I hope not but it sounds like stripping servo gears to me.
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Old Aug 10, 2011, 04:23 PM
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Could be that too

Troy
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Old Aug 11, 2011, 05:19 AM
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Kansas City
Joined Apr 2010
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Gears. Replace them. It's the first gear off the output arm gear. A gear set is about $3.
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Old Aug 11, 2011, 11:18 AM
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If it is stripped gears you need to also discover why they stripped and fix it.
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Old Aug 13, 2011, 10:24 AM
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Joined Mar 2011
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Things to look for on ruor retracts if it is the gear. Make sure your servo travel is only enough for the gear to lock in both positions. Mechanicals are a pain to get right. If you are are stripping gears on a metal geared servo then something is definately out of sorts.

Troy
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Old Aug 18, 2011, 08:09 AM
Lance
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United States, GA, Alpharetta
Joined Mar 2008
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Thanks again for everyone's input. So I took the servo out and when manually putting the gears up by pushing the push rod with my hand, I was able to recreate the noise - so it's def. something inside the wing. Problem is I don't see any rubbing or wear/tear on the gear or the wing. I need fiber optics to see what's happening when the sound occurs
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Old Aug 20, 2011, 03:15 AM
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So you pulled the actuators and there was no sign of anything?

Pull em again and lay some epoxy at all the joints..just keep it off of the flats where the actuators rest on..also check for binding in each individual actuator..figure out which side its coming from..then make sure that the actuator frames aren't twisting when screwed down..

Something is out of true or it may be normal..I avoid mechanicals..

Best advice..ditch the mechanicals and throw a set of robart pneumatics into it and call it done..LOL

Troy
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Old Aug 20, 2011, 09:42 AM
Dweebster
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United States, MA, Charlton
Joined Sep 2008
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Quote:
Originally Posted by twmonroe View Post
So you pulled the actuators and there was no sign of anything?

Pull em again and lay some epoxy at all the joints..just keep it off of the flats where the actuators rest on..also check for binding in each individual actuator..figure out which side its coming from..then make sure that the actuator frames aren't twisting when screwed down..

Something is out of true or it may be normal..I avoid mechanicals..

Best advice..ditch the mechanicals and throw a set of robart pneumatics into it and call it done..LOL

Troy
Troy has a very good point. Problems usually work themselves out the more money you throw at them. lol
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Old Aug 20, 2011, 10:22 AM
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Next step is to take out the retracts to see if it's them making the noise.
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Old Sep 16, 2011, 10:32 PM
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waco,texas
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You can take the plastic wheel wells out but you have to do it very gently or they could be damaged. I've done it and it allows you to really get a good look into the wing. When you're done just glue them back in.
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