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Old 10-01-2013, 01:19 PM   #1
Sabre
 
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Default Newbie Question

I had a question that is likely somewhere in the forum but as yet I have not found it by searching. Now that the rain has started I can finally spend some quality time on the project! I was working on the aileron idler bellcrank and after removing the powder coating and squaring the tabs to each other I can get the washers and bellcrank installed into the fuselage. The question concerns torqueing the bolt, if torqued to the 20 25 in lbs specified for this bolt nut combination the tabs compress binding the assembly. Obviously Im missing something. I have enjoyed the hundreds of post I've read so far and learned much in the process. Thanks for your input.
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Old 10-01-2013, 02:38 PM   #2
Dave S
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Default Re: Newbie Question

Hi Greg,

Look at the torque as a limit not to exceed rather than a specification to meet. A lot of A & Ps would not even use a torque wrench in a situation like this......The goal is to tighten the nut so you get the desired effect which is minimum end play on the bearing and no binding while not exceeding the torque limit of the bolt/nut. For a new person it is best to tighten with a torque wrench to make sure the torque limit is not exceeded in the process. This is not like tightening a spark plug or wheel bolt where an exact torque is mandatory.

You may also find that using thin washers or stacking thin washers might help with getting the fit you want.

I don't know if you are using a nylock nut or a castle nut with a drilled head bolt; but, the goal is the same.

After operating my plane for a while I found that I could adjust the tension on items like this (belcranks) as parts wore in.

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Old 10-01-2013, 03:27 PM   #3
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Default Re: Newbie Question

Thanks Dave. I suspected this but could not verify it with any of the documentation I have access to. Thanks for your response. Greg
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Old 10-02-2013, 05:25 AM   #4
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Default Re: Newbie Question

Has anyone switched out the nuts and bolts for a drilled bolt with a castle nut and safety wire?
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Old 10-02-2013, 05:48 AM   #5
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Default Re: Newbie Question

Esser,

Affirmative. Drilled bolts were used for all control rod ends and bushings for N128DD.

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Old 10-02-2013, 06:31 AM   #6
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Default Re: Newbie Question

Still on cup 1 of coffee, but isn't this a bolt with a castle nut, and a cotter pin? If so just tighten it until it "feels right", and put in the cotter pin.

Regards,
Jeff Hays

Quote:
Originally Posted by Sabre View Post
I had a question that is likely somewhere in the forum but as yet I have not found it by searching. Now that the rain has started I can finally spend some quality time on the project! I was working on the aileron idler bellcrank and after removing the powder coating and squaring the tabs to each other I can get the washers and bellcrank installed into the fuselage. The question concerns torqueing the bolt, if torqued to the 20 25 in lbs specified for this bolt nut combination the tabs compress binding the assembly. Obviously Im missing something. I have enjoyed the hundreds of post I've read so far and learned much in the process. Thanks for your input.
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Old 10-03-2013, 09:50 AM   #7
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Default Re: Newbie Question

Mine are all Nyloc but I think I will be switching to castlenuts.
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Old 10-03-2013, 06:03 PM   #8
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Default Re: Newbie Question

A rod end bearing only requires a locking nut because there is no movement on the hardware. A cotter pin and castle nut is only needed when the hardware is the rotation element of the joint.

A rod end bearing should be tightened in it's mating fork such that the ball of the bearing does not turn against the hardware. The ball should only turn in it's socket.

Using castle nuts on a rod end bearing is not the correct usage of hardware and will result in unwanted wear on the bolt itself instead of the ball of the bearing as it's design intended.
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Old 10-04-2013, 04:55 AM   #9
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Default Re: Newbie Question

During the construction of the aircraft, I had three EAA tech counselor inspections. Two of them were done by a person who was a long time Airline A & P (& RV builder), the other was an EAA tech counselor, FAA employee who worked on certification of in service components for transport aircraft. The DAR also liked the drilled bolts. The A & P tech counselor suggested the switch to drilled bolts/castle nuts & cotter keys. What I didn't put in my original post on the subject was the fact that this also included the use of select fitting, as needed, of thin washers to allow the correct tension ("Feels right") and have correct cotter pin alignment.

For what it's worth,

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Old 10-04-2013, 05:04 AM   #10
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Smile Re: Newbie Question

Dave
I did the same on my installation and it's what I expect to see on Boeing and Airbus installations with flying controls
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