As of 2011, there were 224,475 estimated aviation craft active in the United States. With so many planes and helicopters in use, it’s important to understand field balance equipment and how to properly conduct propeller balancing.
Vibration can be detrimental to every aspect of an aircraft. Control systems, instruments, avionics, and engine mounts can all be negatively affected by harsh vibration. If you’ve started to notice cracks in the spinner or cowling, your first step should be to conduct a vibration analysis at the propeller.
While all propellers come balanced, this is only to ensure even weight distribution. Dynamic balancing works to measure vibrations while in operation. By following proper field balancing procedure and conducting this measurement you can help prevent potential damage and save time, as the whole process only takes a couple of hours.
Balancing is conducted using specialized balance equipment, which is able to measure vibrations and identify where the imbalance is occurring. The balancing process starts by mounting an accelerometer onto the engine, while the optical tach is placed into a position where it can read (or “see”) each rotation of the propeller. For an accurate reading, a piece of reflective tape is placed on one of the blades to designate it as “blade one” in the process. Once hooked into the interface, users can enter details specific to the aircraft which will then be used when you print the final report.
After the aircraft is brought to full power and everything has stabilized, the reading will begin. Typically, an analysis will be done in around seven seconds, after which the engine is shut down and the process of balancing begins. The balancing equipment should produce a readout of the vibration magnitude and the angle of the imbalance. This information can also be used to create a solution that can help rectify the imbalance and reduce the vibration. Depending on the circumstances, the solution can be as simple as adding weight to either the flywheel or prop spinner. The system can recommend where to allocate the weight and distribute it without the need for new screws or bolts. However, in most cases, weight is added by the addition of nuts, screws, and washers. Once the entire process is over, remove the reflective tape to help prevent corrosion.
Utilizing proper balance equipment is the first and best step towards making sure your propeller runs as it should. It’s important to note that any system changes will require rebalancing if a repair or routine maintenance is conducted, the prop is removed, or any change as occurred in the engine. If you’ve never conducted a balanced analysis before, you’ll be amazed at the difference it can make and the amount of vibration that can be reduced. Overall. this not only makes your aircraft safer but much more comfortable to fly.