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#7   How tight do I "Tighten" the "Prop Nut" and "Jam Nut" of my adapter?

The best rule, of course is tight, very tight, but getting the nut tight is sometimes a problem.  I have found that the Tool used to tighten a Prop Nut is sometimes based on Convenience or Availability, not which tool is best for the job.

It is distressing to watch someone at the flying field grab a pair of pliers, or a Glow Plug "T" Wrench to tighten the prop nut.  When you use a lesser tool to torque the prop nut, it feels tight because you are using a tool that does not fit the application.  It might feel tight but it probably isn't, and you are headed for trouble.

We like to use a Box End Wrench that fits the nut properly.  Some brands prop nuts are Metric and some are American sizes, but Tru-Turn Adapters are all Standard American sizes.  Having the right wrench for each of these is somewhat of a problem, but the results of using the Proper Tool is well worth the extra effort.

Some of the newer engines now come with a Double Jam Nut adapter assembly and it is a very good safety device if used properly.  The Primary Nut (The one that goes on first.) should be tightened as described above, tight, very tight.  The Jam nut (Second nut to go on the shaft.) is not any different, it needs to be tight. The theory behind the Double nut is that it will back off sometimes if the engine should backfire, but it should Never come all the way off.  For this safety nut to do it's job right, it must be tight.

The final thing to watch out for is Thread Interference, if the prop nut is too long or too short or you run out of threaded area, it will feel like you are tightening up the Prop but you are not.  In fact, you will be tightening the nut but not crushing (clamping) the prop and you are again headed for disaster.

Fly Safely, It's More Fun!

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