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#2

Dynamic Wheel Balancing / Dynamic Tire Balancing

An example

The tire is installed onto the wheel using conventional methods per Advisory Circular 43.13. 
If you are installing a new tube or tire, line up the yellow line or valve stem (if no line) with the red dot on the tire.  Use the talcom powder as required.  The wheel halves should be clean on the inside and free of grease and foreign material.
Do not pinch the tube when installing the halves.  Be sure the through bolts are not overtorqued.  Some wheels indicate the amount of torque bolts require.  A major reason we cannot balance a specific wheel is because of the wheel halves being over stressed from excessive tightening.
With the valve out inflate the tube several times to help the bead of the tire set into place.   Install the valve and inflate the tire to the proper pressure for the aircraft. 
The tire is put onto the dynamic wheel balancer For proper setting of the bearing races we use these modified wheel adapters
A large nut is used to tightened the wheel on the machine (the speed nut are designed for larger tires)

Measurements are taken of the tire

The wheel diameter is programmed as double of the normal size since 5 inch wheel diameter are not listed

On the first spin the left side indicates an imbalance of 0.1 Oz.
The right side of the tire indicates an imbalance of 0.25 Oz.

We use three different styles of lead weights.  The bottom one is the general purpose one we use.
We use a pair of pruning snips to cut the weights to the necessary amount. We usually start with the side requiring the heaviest weight.  The area is sanded with 400 grit sandpaper and then cleaned with Naptha solvent.
The weight is doubled since the wheel diameter was doubled on the machine.  Here a 1/2 Oz. is installed on the wheel half. The tire is spun again with the new weight installed.  This time the right side reads 0.00, but the left side now reads 0.25 Oz.  A 1/2 Oz. weight is installed on the left side.  
Again the tire is spun again, and this time the right side needs an additional 0,1 Oz.  The left side weight is removed and a 0.25 Oz. is installed in it place. A final spin reveals that the tire is in balance.
This is a McCauley wheel with a 1/2 Oz. weight installed on one side. If we can not fit sufficient weight on the wheel, we will disassemble the wheel and install an additional tire balancing weight inside the tire.  This is typically required on McCauley wheel assemblies.

The top style of weights do not work well on aircraft wheels, although we wasted some on this article.  The middle ones are chrome plated and we use them typically on McCauley wheels.  The bottom "Tape-A-Weight" is our most commonly used weight.  

 
   

   How long does it take?

About 10 to 15 minutes per wheel if done at tire or wheel component change or done in conjunction with an annual or 100 hour inspection.   

If your aircraft is brought in for wheel balance only it takes considerably more time.  The aircraft has to be jacked, wheel fairings, brake components, and wheels removed for balancing and then reinstalled. 

You may carry in your wheels (without bearings) for dynamic balancing.  We can usually accommodate a set without an appointment.  Cost for carry-in wheels per balance is $20.  Call us at 1-800-262 for more information.

 

Back to wheel balancing #1

 

 

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Last modified: March 01, 2007