When people refer to tracking the blades, what does this mean?

The track that each main blade takes as it goes around. Both blades should be adjusted so they track the same.

Tracking refers to differences in the pitch of the main blades. If your blades are "out of track" one blade will hve more pitch and lift than the other causing the main rotor head to be out of balance. To initially check tracking, spool up the heli to just before lift off, get down and look at the the edge of the rotor disc. If your blades are tracking well (at equal pitch) you will only see one blade. If they are out of track, you will see both blades, one slighty higher than the other like a very thin sideways V. The blade that appears on top is at a slightly higher pitch than the other. If you can see a difference, you need to adjust one of the blades pitch to compensate. Every heli is different on this, but usually you adjust it by increasing or decreasing the length of one of the control arms on the head. Most blades come with different colored tracking tape. Place the colored tape at the end of the blades and you can see which blade is high and which is low.

If your blades are true (decent carbons or glass) and you set it up with a pitch gauge to have the same pitch on both blades, you probably wont have to mess with it.

One of the things I do to track them when I have to is use erasable marker to slather one blade tip red. It doesnt change balance like tracking tape and it wipes off when you're done.

If your blades are true (decent carbons or glass) and you set it up with a pitch gauge to have the same pitch on both blades, you probably wont have to mess with it.

Not always true and more and more people don't even know what a pitch gage is....

One of the things I do to track them when I have to is use erasable marker to slather one blade tip red. It doesnt change balance like tracking tape and it wipes off when you're done.

Great idea!