John Benario
Senior Heliman
Location: Atlanta
| The Schluter tail rotor uses a 2.5 mm bolt to hold the grip to the hub and it has proven to be satisfactory, so the 3 mm bolt is sized properly. There are a number of possibilities.
The first issue is the hardware included in the kit is of poor quality. I replaced particular bolts on mine with better parts.
The second issue is the supplied washers are very soft, and have a too large id. This issue is most noticeable on the 5 mm id washers under the main blade spindle bolts. Those washers on mine almost sheared from the blade loads. I replaced the 3 mm id washers in my tail with better ones and the 5 mm ones on the main blade spindle with machined steel ones.
The problem with the washers is when they compress the bolt loses preload which exacerbates other issues.
With the soft bolts overtightening is a possiblity. Proper tightening torque for high quality 3 mm bolts is 17 oz-in. That is about the same grip strength in your hand as a strong handshake. The stock bolts are not high quality so the tightening torque would probably be more like a loose handshake.
My experience with the Synergy tail is that it is a good, reliable design, if built properly.
I use Loctite 290 (DO NOT use blue loctite 242), hand tighten the bolts, and then turn maybe an 1/8 turn more. It is the loctite that holds them in, not the tightening torque.
The other nuisance build areas of the tail are having to ream the pitch fork holes for the 2 mm pins, replacing the 2 mm pins with hardened ones (JR), working the 2 mm holes in the pitch links by hand until they are a smooth fit on the 2 mm pins, shimming the tail output shaft so it is precisely spaced in the tail gearbox. I also use the black balls because the chrome balls are very tight in the links and cause a lot of friction in the tail assembly.
John Benario |
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