Balance rotor blades
An essential part of building and setting up every heli is to balance the main and tail blades both dynamically and statically. Although it's not difficult to do, it does take a little time to do it correctly. To get the best results, the blades must be balancing in motion such as a tire is spun up and weight added to balance the shake. This could be done on a heli as well by trail and error but the explained method will get you very close if not almost perfect balance. If done correctly, it should eliminate almost all vibrations. Trim tape to be used for tracking and clear tape for adding weight and a marker for marking the CG.














Blade tightness
Loose blades can cause crashes. When the rotor is overloaded from too much collective and cyclic together then the blades can pivot in the blade grips. In the right situation (pulling back on elevator) the blades can chop the tail boom off in flight. This also happens on the ground when a beginner pilot lands too hard with loose blades. A lot of people think the blades bow down and get the tail boom, but what really happens is the blade pivots in the blade grip. When this happens and there is a some back elevator input then the blade can easily reach the tailboom. A good tip for autorotations is to add a little forward elevator just as the helicopter sits down. So what is the correct amount of tension the blades should have? There is an easy test, grab a blade grip with one hand and a skid with the other. Hold the helicopter on its side with the main blades stretched out and parallel with the ground. Now give it a bump. If either of the blades pivoted in the blade grip then you need to tighten the bolt for that blade.


Blade tracking
What is blade tracking? If you look at the rotor disk from the side you should see a thin line. This means that both blades rotate around to the same position the other blade was in. If the blades do not align right then you will see a thick line or if bad enough you will see two lines.

Some examples are shown in the picture below. The top image is of the blades in track. The middle is of just one side out indicating the flybar is bent, paddle not aligned, etc. The bottom is a typical out of track situation



So why do blades need to be tracked? Most of the time if the two blades are manufactured with close tolerances then they will not need additional alignment. However if one blade flexes more then the other or the blade has a warp in it then the purpose of tracking is to bring that blade in the same path as the other one.

First step: Before tracking the blades you need to have one side of the rotor head marked so your adjustments will be consistent. In addition to using this so you can keep up with the link you are adjusting, you can also use this so if you take the blades off you can then get the blade back on the same grip and not have to re-track the blades.

Second step: Static tracking: this is the process of adjusting the pitch of each blade so they are the same on the bench. Almost all of the time this is the only tracking you will need to do. If it is wrong in the air then one of the blades must be flexing differently then the other and you will need to adjust the links to compensate. Start the process by sighting down the end of the blade and move the collective to a position that the tip of the leading edge and tip of the trailing edge are aligned with the flybar. Next rotate the rotor head 180 degrees and sight down the end of the other blade. Adjust the long link attached to it so that that blade is also aligned with the flybar. This will now have both blades at the same pitch settings.

Third step: Hover the helicopter and look at the edge of the rotor disk. Do not get to close to yourself. While looking at the blades it is easy to not pay attention to the helicopters position. It is a good idea to let a friend look at the tracking while you concentrate on hovering still. If the blades are out of track then land and look for the blade you marked. Adjust the link one turn, snap it back on, and check the tracking again. If it is worse then land and find the marked blade again and adjust the link two turns in the opposite direction. If one turn is not enough then go to the unmarked blade and adjust one turn the opposite direction. By rotating between one blade to the other you will keep your pitch range closer to the original range.



Source: summary of important information from different internetwebsites