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Retorquing Bolts - 0.8 hours

The new version of the manual specifies new torque values for some of the bolts. It does this in a table that is easier to understand but that also changes the values we used for a number of the AN3 bolts in the wing. Fortunately, it specifies higher torque values than were used so the bolts can just be retorqued without replacement or replacing the nuts. The reason for this higher torque value is to compensate for the higher force needed to turn a locking nut on a bolt at all.

Specifically, the pervious version of the manual specified 20-25 in/lbs and the new manual specifies 30 in/lbs. This is a small change but one that should be applied since the bolts are still accessible. Specifically, the AN3 bolts used to hold the fuel tank straps, the bolts used to attach the machined tail ribs, and the bolt used to attach the bracket to the center aileron hanger all needed to be retorqued.

Removing the existing torque seal from these bolts was a bit of a tedious process but I was able to remove enough to fit a socket on the nuts using a box cutter blade as a scraper. Torquing and then re-applying torque seal was then a simple process. The one exception to that was torquing the bolts holding the machined tail ribs on. The nuts on these bolts are not accessible using a socket so a crow’s foot must be used. Because this changes the arm of the torque wrench, a new indicated torque value must also be calculated. Figure 7-2 on page 7-8 (Par 7-43) of AC 43.13 gives the formula for calculating the necessary indicated torque value. In this case, 29 in/lbs. Once that was calculated, using the crow’s foot to retorque was also very straightforward.

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