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12iS empennage built Q's

KEG

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Reference 12iS build manual page 07-03:

Anyone know a torq spec for the AN3-10A bolt that holds the rudder to the upper and lower hinges? It appears designed to have the nut bottom out on the bolt threads, however, I do not know if it will squeeze the ears of the hardware together. Also, is there a clearance spec for deciding what size washers are inserted in between the hinge bracket and their attaching hardware??
 
You're talking about the 2 bolts that hold the rudder onto the plane.. I don't have Section 07 in front of me here, but there should be a washer(s) immediately on top of and immediately below the bearing (you're talking about these).. in addition to a washer immediately below the bolt's head.. and one immediately above the nylock nut.

I believe the diagram said to use a "thick" (1/16th") AN960-10 or a "thin" (1/32nd") AN910-10L washer, as required. By the way, sometimes 2 thin washers are slightly (a hair) thicker than 1 thick washer or vice versa.

I filled up the gap between the flanges and bearings with washers as best as i could without bending the flanges (stuffing too many washers in). Of course, use the least amount of washers as you can. You don't want any bending stress on the flanges when you tighten up the bolt.

The nut, if I remember, is a nylock AN365 nut. There is a small table in the beginning of your KAI (Kit Assembly Instructions) that shows what the torque should be for an AN3 into a nylock nut. Remember to tighten the nut until all of the threads are engaged into the nut, then measure the torque needed to screw it in further (i.e. slowly increase your torque wrench until you can start turning the nut.. to get a close idea of what it takes to overcome the friction). Add that number to whatever the table tells you. The idea is that the friction doesn't really count towards the number that the table tells you.. so you'll end up tightening the nut an extra (10-15-20? in-lbs) more than the table says.
 
If you use the correct washer stack the nut should not "bottom out" - you should be able to fully torque. If you are using correct washer stack but still running out of threads, try next size lower bolt or add another washer if allowed.

Torque specs are in Section 5, (look for section 5.20). For nylock and metal lock nuts be sure to add the friction torque (torque generated by the locking method of the nut) to the torque value in the table. For AN-3 the typical friction torque for nylock nuts is about 10-15 inch pounds, recommended torque in section 5.20 is 28 inch pounds (for self locking nuts) thus a typical "final" torque value of 38-43 inch pounds or so (but use the actual number from your measured friction torque value).

FYI - much easier to measure friction torque using an indicator type torque wrench (I like / use this one: https://www.amazon.com/gp/product/B00461AZ7C/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
 
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