Torque values
David,
Here is my understanding of tightening the critical wing spar bolts.
First, the standard torque values for most aircraft bolts can be found in AC-43.13B. in Chapter 7.
The entire Advisory is available online and can be dowloaded from various sources including:
http://rgl.faa.gov/Regulatory_and_G...99C827DB9BAAC81B86256B4500596C4E?OpenDocument
Another excellent source for anything to do with aircraft hardware, including torque values, in an easy-to-understand format with lots of pictures, is the Mechanic's Tool Box, which is a CD-ROM based program available from Sacramento Sky Ranch. For those builders without a lot of help close by, it is a godsend.
The AN bolts are torqued at standard tension values, so for AN3 the value is 20-25 inch-lbs. The NAS bolts are torqued as other steel bolts unless specified differently by the aircraft manufacturer, remembering they are close tolerance bolts, having a friction fit and should either be torqued from the nut side or an allowance made for the friction value and on larger bolts using stop nuts, the prevailing torque values should be taken into account as well. The values in AC-4313B are for dry threads, whereas some bolts, say in engine assembly, are specified to be lubricated.
Vans assembly manual for the 6 models, unlike some certified aircraft manuals does not specify critical torque values. It is up to the builder to be knowledgeable in the details.
Dave A.
6A build
