Fixed-pitch prop bolts

[Paul Eastham]

After installing my fixed-pitch prop a while ago, I came across this in the Sensenich installation guide:

"Place a washer on each attaching bolt and insert the bolts through propeller holes, engaging the bolts by hand into the threads of the crankshaft flange bushings. If the bolts do not thread in easily, something is wrong. Remove the propeller and recheck the bolt threads and flange bushing threads for damage or foreign material."

As I recall, some of the bolts screwed all the way in by hand, others got a bit balky after a few rotations and went in until bottoming out with very light wrench pressure. I did check the bolts and threads for obvious problems, several times. Removal of the bolts showed some slight marring of the cad plating around the area of the front bulkhead. I rebuffed the insides of the holes as a result.

Should I look for more problems or is this normal?

[DanH]

Paul,
What they're saying (for the most part) is that later in the process, when you tighten the bolts to the specified torque setting, force spent overcoming thread friction will result in reduced bolt preload (propeller clamping force).

You can compensate by measuring the torque necessary to turn against thread friction, and adding it to the specificed torque. The easy way to measure is a beam type torque wrench.