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  #1  
Old 06-23-2019, 08:24 PM
Eddie P's Avatar
Eddie P Eddie P is offline
 
Join Date: Oct 2007
Location: Reno NV
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Default Speaking of Jam Nuts...

Hi guys, I’m looking for opinions and techniques.

I have been quite attentive to my “nuts” on preflight thanks to the great information here and the video posted to Youtube featuring Vic Syracuse speaking on the more notorious leisure attitudes around RV preventative maintenance, care and feeding. Jam Nuts were an emphasis area among others.

So lo and behold, after many recent flights thinking, “when am I gonna find a loose nut” I saw something different. One of my torque paint stripes on a Jam Nut was partially missing. Sure enough, the jam but on the outer left elevator backed off a few degrees after the last flight. I tightened it up before flight. And admittedly, it was an awkward fit for the wrench I was using.

I would love to hear and see how you guys “keep your nuts in check” without buggering up the nuts or airframe with wrenches. Also, what torque and how do you measure it?

I did not build my 8 as much as I wish I could have. So my question comes from a non-builder reference. On the pre buy inspection there were a few jam nuts that had started backing off in the tail so they were re torqued and striped for easy identification of possible backing off in the future. So this jam nut has about 20 hours of service before moving again. Admittedly, I have done several stalls and incipient spins to get used to the stall and departure handling of this particular airplane so the tail has been worked a few times in addition to treating the plane to about 50 landings since the nuts were torqued and striped. Interesting, none the less.
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Last edited by Eddie P : 06-23-2019 at 08:33 PM.
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  #2  
Old 06-23-2019, 09:14 PM
rightrudder rightrudder is offline
 
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Hey Eddie,

On all my jam nuts, I applied LocTite, torqued them to final spec, then applied Torque Seal, and nothing has budged in 3.5 years. It is difficult to get a wrench securely on these buggers (especially through the openings in the elevators) so I modified an offset box wrench, cutting off at least the outer third of the box...think flare wrench for brake line fittings. Works like a charm.
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  #3  
Old 06-23-2019, 09:18 PM
rv7charlie rv7charlie is offline
 
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Are you speaking of actual jam nuts, as used to secure a rod end bearing ('heim joint') on a pushrod, or a nyloc nut, used on the bolts inserted through brackets and the ball of a rod end bearing?
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Old 06-23-2019, 09:18 PM
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Steve Melton Steve Melton is offline
 
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Quote:
Originally Posted by rightrudder View Post
Hey Eddie,

On all my jam nuts, I applied LocTite, torqued them to final spec, then applied Torque Seal, and nothing has budged in 3.5 years. It is difficult to get a wrench securely on these buggers (especially through the openings in the elevators) so I modified an offset box wrench, cutting off at least the outer third of the box...think flare wrench for brake line fittings. Works like a charm.
same for me.
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  #5  
Old 06-23-2019, 11:11 PM
Eddie P's Avatar
Eddie P Eddie P is offline
 
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Location: Reno NV
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Quote:
Originally Posted by rv7charlie View Post
Are you speaking of actual jam nuts, as used to secure a rod end bearing ('heim joint') on a pushrod, or a nyloc nut, used on the bolts inserted through brackets and the ball of a rod end bearing?
These particular jam nuts (of many types thought the plane) are the nuts that screw down onto the elevator spar (and attach to the rod end thread. I think these jam nuts pre load the rod end thread so it has support on both ends of the spar). The rod end threaded bolt that the nut is mounted to creates the elevator side of the elevator to stabilizer flight control hinge mount. These are also used on the rudder.
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  #6  
Old 06-23-2019, 11:17 PM
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bruceh bruceh is offline
 
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Just get a cheap set of deep offset box wrenches from Harbor Freight. Take the cutting wheel to the end of the box part of the wrench to open it up enough to get it over the threaded portion of the rod end bearing. The offset allows you to get it on the jam nut and have the handle of the wrench be able to clear the skins of the HS/VS/Rudder.

https://www.harborfreight.com/8-piec...set-32041.html
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  #7  
Old 06-23-2019, 11:55 PM
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Eddie P Eddie P is offline
 
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Thank you for that link and description. Very doable. How do you know / verify the proper spec for torque? I'm assuming in this case it's a "TAR" torque device (That's About Right)?
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  #8  
Old 06-24-2019, 08:29 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by Eddie P View Post
Thank you for that link and description. Very doable. How do you know / verify the proper spec for torque? I'm assuming in this case it's a "TAR" torque device (That's About Right)?
Torque value on a fastener can be measured in many different ways....

A wrench such as the one in the link, coupled with a spring scale and some simple math can give you an accurate torque reading.
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  #9  
Old 06-24-2019, 08:05 PM
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Eddie P Eddie P is offline
 
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Great idea, thanks. I'll have to see if I can google a few images of that type of torque contraption.
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  #10  
Old 06-25-2019, 07:21 AM
FinnFlyer FinnFlyer is offline
 
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Spring scale = fish scale.

Hook fish scale to end of wrench at 90 degree angle.
Torgue = distance from center of nut to fish scale attach point x fish scale reading.

Or Torgue required / distance = what you want to the fish scale to read.

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