Originally Posted by
hoss183
In fact its even more clever than that. When visiting BAs maintenance facility, i was shown what the do on a/c during a C check.
The blades are taken out and inspected an weighed, thats fed into a computer and it defines the optimal position for each blade being put back to achieve the best balance.
The most important data the computer needs to know about each blade is not its weight, but its moment of inertia relative to the rotor axis, but to make a machine for that is straightforward.
And the proposed rulemaking concerning CFM56-7B fan blades (referenced here earlier) should give you an idea how quick and easy it is to inspect the blades. The estimated cost for the operator is a mere $170 per engine (2 work hours), which is nothing in aviation.
And I would assume that when you do these inspections, the easiest way is in fact to just number the blades and their position on the disk with a permanent felt-tip marker.
Bernd