[Top_prop]

Just finishing up my rudder and I need to torq two #8 countersunk bolts.

The Van's manual only lists torq specs for #10 and bigger.

The bolts are AN509-8R14 with AN365-832 nyloc nuts...

Searches turned up nothing... please help!

Thanks,

Tom

 

[frankh]

If it breaks

Its too tight..You think I'm joking?

Really I'm not..You can tighten these bolts up to the plastic deformation range (namely it streaches) and that will be just fine.

As aviation fasteners use torq values that normally would be considered way to low (because they are used in shear, not tension) then I would suggest using whatever you use or the #10 fasteners.

And it if it doesn't strip or break that will be just fine.

The other tired and trusted method is to snug it up by hand.

Frank

 

[az_gila]

Unlike Frank...

...I prefer numbers....

The AN509 screw is 125,000 psi material.

AC43.13-1b list 8-32 max torque for a 90,000 psi material bolt at 20 inch pounds - it's in Table 7-1

I would go with this number, but if you wanted to scale it for maximum torque for the 125,000 psi material, it would work out to be 27 inch pounds.

...but, are the standard nuts good for this torque?

Go with the 20 inch-pounds number with the prevailing torque of the self lock nut added.

 

[frankh]

I wonder

where I put that torque wrench?

If you HAVE to have numbers then good luck getting an accurate torque on the most important fasteners in the whole airplane..Namely the wing bolts.

I mean there is so much "stiction" on the bolt shaft you have to torque the nuts..and as you can't get to the nuts with a socket on an A model its wonder were all still flying..

Frank

 

[az_gila]

...but the bolts you mention...

where I put that torque wrench?

If you HAVE to have numbers then good luck getting an accurate torque on the most important fasteners in the whole airplane..Namely the wing bolts.

I mean there is so much "stiction" on the bolt shaft you have to torque the nuts..and as you can't get to the nuts with a socket on an A model its wonder were all still flying..

Frank

...are all in shear... the nuts are almost optional...

If you look at most sailplanes, the load on the wing bolts is higher (longer wingspan, more leverage) and they are usually clevis pins, or a custom made equivalent.

A builder asked for a reference and numbers and I gave them...

NOTE- I'm not recommending leaving the wing bolt nuts off....