Do All Bolts Get Torqued?
 

I was wondering if ALL bolts should be torque even when not called out in the manual? Specifically I am finishing the rudder and putting the two bolts in the skin to hold the rudder counter-weight. I believe these are AN539-832A bolts (or something like that). The manual doesnt say to torque these and even if it did, the 5V section on torque doesnt mention AN539 (unless you just refer to AN5 as the same. Any pointers?

Yes, all bolts should be installed with a torque wrench. The problem for most new builders is that the bolts are installed over torqued if a torque wrench isn't used. After a while, you'll get a pretty good idea on what the right amount of torque should be and know what it feels like.

Also, another good practice is to use torque seal inspection lacquer once you have torqued the bolts to ensure that they haven't moved after installation. The lacquer is also a good memory jogger if you termporarily install bolts. i.e. no lacquer means you have to re-torque the bolts for finally installation.

bob

Any idea how to find the proper torque for this bolt then? Is the AN539 the same as the AN5 they refer to in the build book? It says 100-120Lb/Inch.

Not too sure of plans sets for anything but a 10, but my torque spec table was in the first few sections of the plans, the ones that come in 8 1/2" x 11" binder.

Section 5 as I recall.

Not sure about the 10 hardware but I'm positive the balance weight is not held on with a AN5 (5/16") bolt :rolleyes:

The 7/8 aircraft use a #10 CS screw if I recall correctly.

If you provide the exact hardware call out then I can help.

Thanks. The exact bolt is listed as AN509-8R14.

That's a #8 screw, I always recommend attaching the weight with an adhesive like proseal then tighten the screw "Gudintite" with a screwdriver. Screws don't have a torque spec. per se, just tighten them with a screwdriver.

Official torque specs start with the AN3 (#10) bolt and go up from there.

I agree in theory, but not in practice.

Bob K.

Good maintenance practices require all bolts being torqued. If construction or maintenence documents don't call out a specific torque, standard torque values should be used. FAA Circular, AC43.13-1B provides standard torque values, methods and practices with accompanying hardware identification resources to aid in identifying the correct torque tables to use (ie: course thread vs. fine thread fasteners).

Now sayng all that, I realize human nature is difficult to fight. I have worked in aircraft maintenence, maintenance management and development for 34 years and have come to a set of personal rules I use on my airplane.

1. Over-torqued is just as dangerous as under-torqued.

2. If the failure of a fastener can potentially, or precipitate related failures that have the potential to, hurt/kill me, endanger others on the ground, or damage/destroy my airplane, it gets torqued. Fasteners not meeting this definition receive German Torque (gutentite). This process makes you think about each and every fastener in a unique way. It is sort of like doing a quick, mini FMECA on everything (Failure mode, effects, and Criticality Analysis).

3. All safety-of-flight hardware recieve torque stripes: flight controls, landing gear, control and flying surface mounts, engine mounts etc.

4. Never use a dog bone or crows foot in anything but the 90 degree position. If unable, suck it up and do the math (not a frequent need).

5. Use torque wrenches slowly and properly. Not doing so WILL change the applied torque.

Jekyll

A few should not be torqued such as rudder pedal pivot points, rear spar attach, or anything going into the nylon blocks (the block will deform before you get to the intended torque)--ask me how I know. There are probably some similar othe ones not immediately coming to mind.

Steve Johnson
RV-9A --flying
Abilene, Tx