TAF advice on main spar pocket hole
I am taking TAFs advice not to disassemble the main spar simply in order to create a pocket hole for one rivet. They also advise the existing AN3-12A bolts are fine sine these are mostly under tension, the slightly incomplete coverage of the spar thickness by the bolt grip does not matter. They have approved however of changing to an AN3-13A bolt with one washer under the head and two washers under the nut. Will decide later what to do. These bolts could be changed one by one without disassembling the spar.
TAF also advise:
- these bolts should be torqued to 37 in-lb, including the nylock torque. This torque can also be used for all other AN3 bolts as well.
- AN4 torque specs are 50-70 inch-lbs for normal nuts. If elastic stop nut is used then you need to add 15-19 in-lbs.
- Duralacis ok, but the threads must be kept free of it.
- doubler on the flange of rib 1 is a good idea to compensate for the absence of the pocket rivet.
- any bolt tightening sequence is acceptable as along as you don’t tighten just one bolt 100% and then move to the next bolt
This post is from Adam Dickson