Bellcrank bolts

[vonjet]

When bolting up a control bellcrank to its angle brackets it is best practice to use a bolt with castle nut and cotter pin or metal stop nut?
Also if using the castle nut and cotter pin do I torque the bolt to normal spec since the bellcrank rides on a bearing.

[briand]

Yes on the torque.

You could use these if it makes you feel better:

http://www.aircraftspruce.com/catalo...es/ms17825.php

[GAHco]

Originally Posted by vonjet

When bolting up a control bellcrank to its angle brackets it is best practice to use a bolt with castle nut and cotter pin or metal stop nut?
Also if using the castle nut and cotter pin do I torque the bolt to normal spec since the bellcrank rides on a bearing.

The torque depends on if it is in tension or shear.
Typically when a fastener is going through a bearing it is considered shear, which is a lower torque value.

[pierre smith]

....The plans call for a simple locknut because as has been pointed out, the bolt is not a bearing. Don't bother with all the trouble trying to put a cotter pin in such a tight area.

The rudder and elevator hinges also have balls so only need bolts and locknuts since those bolts aren't bearings either.

The rudder cables, however, use the bolts as bearings, then you need castellated nuts and cotter pins.

Regards,

[briand]

Originally Posted by pierre smith

....The plans call for a simple locknut because as has been pointed out, the bolt is not a bearing. Don't bother with all the trouble trying to put a cotter pin in such a tight area.

The rudder and elevator hinges also have balls so only need bolts and locknuts since those bolts aren't bearings either.

The rudder cables, however, use the bolts as bearings, then you need castellated nuts and cotter pins.

Regards,

But he's asking about the bellcrank.

As stated by Van's something like: Use those two large (5702-95-30) as capture washers in case of bearing failure. Those two washers or the ID of the seized bearing will then ride on the bolt. Just sayin' if the dude wants to sleep better or something.

Gahco:
As far as torquing a 3/16" bolt (for the control surface rod end bearings) to the standard 22-25in-lbs., why would you torgue these any less than 22in-lbs.? With a brand new nylock insert (which has a fair amount of friction) I would be concerned about the nut seating if I started trying to guess a more "adequate" lower torque. Where do you find that other/"lower" torque table? Van doesn't provide it in his manual (at least for the RV-8)

[GAHco]

Originally Posted by briand

But he's asking about the bellcrank.

As stated by Van's something like: Use those two large (5702-95-30) as capture washers in case of bearing failure. Those two washers or the ID of the seized bearing will then ride on the bolt. Just sayin' if the dude wants to sleep better or something.

Gahco:
As far as torquing a 3/16" bolt (for the control surface rod end bearings) to the standard 22-25in-lbs., why would you torgue these any less than 22in-lbs.? With a brand new nylock insert (which has a fair amount of friction) I would be concerned about the nut seating if I started trying to guess a more "adequate" lower torque. Where do you find that other/"lower" torque table? Van doesn't provide it in his manual (at least for the RV-8)

Why load a fastener to a tension load to do a shear job is my theory.

My understanding is that the you are supposed to add the friction torque of the nut (before bottoming) to the recommended torque (when using a resistance type locknut, so keep that in mind.

The other Torque Table is actually the same old Table 7-1 IN ac43-13-1b
There are two major headings

http://www2.tech.purdue.edu/at/cours...3-1B/CH7_3.pdf

Shear Loads and Maximum Tightening limits.

With the 10-32 fastener installed in shear with a MS20365-1032A or an AN310-3, the torque is called out as 20-25 and develops 40,000 psi tension per the chart.

With the 10-32 fastener installed in shear with a MS20364-1032A or an AN320-3, the torque is called out as 12-25 and develops 24,000 psi tension per the chart.

Max Allowable Tightening limits

With the 10-32 fastener installed in shear with a MS20365-1032A or an AN310-3, the MAXIMUM torque is called out as 40 and develops 90,000 psi per the chart.

With the 10-32 fastener installed in shear with a MS20364-1032A or an AN320-3, the torque is called out as 20-25 and develops 54,000 psi per the chart.

Per experience you can substitute a full height tension nut for a low height shear nut so long as you do not over torque it for the application.

However you can not put a shear nut where a tension nut belongs.

The range of torques (shear min to tension max) when you consider the applications is quite wide.