The secondary drive unit has been the object of a great deal of controversy among RotorWay builders/pilots. There has been a rash of secondary failures on the 162F and RotorWay was slow in recognizing the problem. As a matter of fact, they still won't admit there was a problem with the secondary units; however they came out with a replacement unit. The original secondary unit had a 30mm shaft whereas the new secondary has a 35mm shaft. I was told by Tom Smith (RW President of Customer Service and Technical Support) the secondary failures were "probably" due to improper installation by inexperienced builders. He also said that he believed most of the secondary failures occurred on ships that had the Pro-Drive belt system installed. He told me the new 35mm secondary was just RWs effort at continual improvement. He said I could send in my brand new, never used, secondary and trade up to the new 35mm secondary for $900. I tried to probe deeper to see if Tom would tell me about secondary failures at the RW flight school. They don't use the Pro-Drive system and are built by factory experts. I soon got frustrated and realized that Tom was not about to give me any more information than was absolutely necessary. He never told me of the factory built ships that had secondary failures. I learned about that from other RW pilots that were at RW when the failures occurred. My conversation with Tom was disappointing. |
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I was extra cautious installing the secondary unit. I took extreme care to make sure the secondary alignment had zero deviation from specification. The electronic level I use is accurate to 1/10th of a degree. I made sure the square tubes that are used throughout the building process as reference points were absolutely level fore and aft and laterally. I wish I had taken more pictures of the secondary mounting process. I was so intensely focused on the task at hand that I forgot to take pictures during part of the process. |
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| Once the frame is perfectly level there is a process to determine how far the secondary mount is out of alignment. To correct for the alignment error, the secondary upper bearing mount is "shaved" to compensate. Before I began the machining process, I used shims to get the upper bearing mount perfectly level on the work bench. |  |
Originally I was going to take the secondary unit to a machine shop for this delicate operation. However, several of the more experienced builders convinced me that I could achieve perfection by using a hand file. I got pointers on how to use a smooth cut mill file to maintain a flat surface across the span of the mount surface. I decided to go for it. I got to where I could feel when the file was taking the proper bite. Too much pressure caused the file to "clog" with metal shaving that would scratch the working surface. With a little practice I got the technique down so I got an even smooth cut all the way across the mount surface. |
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| determined earlier the bearing mount needed a 4.1 degree angle on it's surface. I would file a little then check the surface in 5 locations across the surface. I repeated this process for about 30 minutes until I got exactly the result needed. |  |
| Here you can see the secondary mounted on the air frame with a perfect 90 degree reading off the bearing housing. |  |
You can see here the secondary drive pulley has a perfect 0.0 alignment. It has 0.0 alignment from any location on the secondary pulley. Wow, what a satisfying feeling! This baby is dead nuts on! My shop buddy Chip suggested I name the ship 0.0 (Zero Point Zero). It would be fitting. |
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After getting the secondary dive alignment correct, I used brass shims of equal thickness in the upper and lower secondary mounts to achieve the proper belt tension. I used an electronic fisherman's scale and metal yard stick to measure the deflection of the drive belt at 10 lbs. |
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