Rebolting wing main spar caps

On advice from TAF the recommended torque setting for the AN3 bolts (including the allowance for the friction of nylon nut inserts) is 37 in-lb. On the Toledo torque wrench this is on the 35.4 in-lb division, with the vernier offset set to 2*(37-35.4)/17.7 = +0.18 Nm

Checking with the rig described previously, I get a force of 0.59kg => torque = 36 in-lbs (vertical arm, midpoint hole)

Increasing the vernier by 4 in-lb = 0.45 Nm for a resultant vernier of 0.58 Nm or 5.2 in-lbs or overall nominal torque of 40.6 in-lbs

With rig: force of 1.27kg => torque = 38.6 in-lbs (vertical arm, midpoint hole)

Setting the vernier back by 0.18 Nm (1.8 in-lbs) to 0.40 Nm I get

With rig: force of 1.24kg => torque = 37.7 in-lbs (vertical arm, midpoint hole)

I'll go with this for the main spar AN3 bolts. For reference the wrench nominal setting is 35.4+0.4*8.845 = 38.9 in-lbs

Ensuring the AN3 bolts would continue to be able to be slid into their holes, the AN6 and AN5 bolts were torqued to 20Nm (177 in-lbs) and 15Nm (133 in-lbs) respectively, their full design torque values.

The spar caps were rebolted with AN3-13A bolts with one AN960-10 washer under the head and two AN960-10 washers under new AN365-1032A nuts. As discussed previously, the use of a longer both than originally used (AN3-12A), combined with two additional washers ensured the nut had the same relationship to the thread as before, but with the bonus that the grip of the bolt passed fully through all spar layers.

A recheck of the wrench after work completed: 1.34kg => torque = 40.7 Nm, at the top end of AN3 but ok (considering the original AN3 appeared to be torqued to 100+ in-lbs)

The bolt grips and washers where contacting with the spar caps were smeared with the thin layer of Duralac yellow.

As discussed previously, I considered retiring the inner spar cap layers as I was dissatisfied/irritated with the fact I removed slightly more edge than strictly necessary when chamfering. Right away, when querying this, TAF indicated the chamfering was fine however. While ruminating on this a bit I actually purchased replacement spar caps at minor cost with the lead time in mind so to have the option of considering replacement at greater leisure. In the event I worked to fit the new spar caps - and TAF was very supportive(patient!) indeed with some technical guidance on this - but in the end the result was not quite as good a fit as the original caps. The AN6 holes as well as some of the AN3 holes were not as tight a fit or would be very slightly elongated to match the original wing (Actually TAF also confirmed this would not be a problem either, on just one or two layers out of the stack). But in addition there would also be all the work to do again on the chamfering.

In view of TAF's original assessment and some further opinions on the matter I decided to use the original caps, shown here.