drill size bellcranks

[JurgenRoeland]

hi Everyone,

I have a small question (probably stupid).
I'm wondering why the manual on the install kits of roll and pitch servo tell you to drill a #11 size hole in the bellcranks.
Is there a reason why this is #11 ?

In the entire aircraft I have always drilled and reamed #12 holes for AN3 bolts so I'm just wondering if there is a specific reason for these to be called out as #11.

greetings and happy Holidays
Jurgen

 

[Rhino]

That's the preferred clearance size for the bolt, as the diagram says. If you want to know why that's the preferred clearance size, you might need to ask Dynon.

 

[jnmeade]

You note the pitch servo says "or preferred clearance for AN3 bolt). #11 is just a little larger than #12, for whatever difference that makes.

 

[Rhino]

Correct, and Dynon would be who you should ask about what difference it makes.

 

[jnmeade]

According to the instructions, Dynon has already stated their position. Use #11 unless you have reason to use a different hole diameter consistent with an AN3 bolt. AN3 bolts thread diameter tolerance permits up to 0.189, so a #12 would theoretically work.
What do you want Dynon to tell you? That it's OK to follow their instructions?