What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Hartzell c/s prop bolts...what thread are they?

flyboy1963

Well Known Member
Hartzell c/s prop bolts...what thread are they? 7/16" x 20?

So took my prop off, and one bolt came out pretty slow...the others could be turned with fingers. I'd like to clean up the threads on the crank insert, assuming the last guy may have bunged the first few starting the bolts.
.....but a number of my 7/16" x20 taps just don't go in easily, and I don't want to cut new threads!
Anyone know what's going on here? I want to ensure they all torque up evenly.

and how dry is 'dry' torque? as spec'd by Hartzell.
they all have a film of oil on them from the whole operation.
 
Last edited:
Maybe talk to a mechanic before tapping the prop bushing. These are pretty critical fasteners and are designed to be easily replaced.
 
I thought prop bolts (and perhaps their bushings) have rolled threads instead of sharp cut threads.
 
You don't want a tap, you want a thread chase. It is designed to clean up threads without cutting new ones. They work very well for minor thread imperfections. I don't know the thread specs for the inserts, but can't imagine that a quality tap would create significant problems, if used for clean up. Though that is not really the place to experiment. You can also buy a new insert for under $40. They press in/out fairly easily.

Rolled threads are only done for male threads, like a bolt. Female threads are always cut with a tap.
 
Last edited:
Back
Top