Prop Spinner

Started May 1, 2008

I have a fixed pitch, Sensenich prop and purchased the 13" spinner that's available from Van's aircraft.  The following will not apply to those of you with a constant speed prop. To fit the spinner, the prop was mounted onto the engine with spinner front and aft bulkheads that came with the spinner, installed.

Now to cut the spinner to fit around the prop blades. The first step is to find two points exactly opposite of each other on the spinner dome.  To do this, I used some heavy shipping paper and traced around the spinner dome:

The circle was cut out and then folded exactly in half.  A mark was made on each end of the fold line and the circle was taped to the floor to prevent it from moving:

Next the spinner dome was placed back on top of the circle and the the marks were transferred to the spinner dome.

On the Sensenich website, they have placed some full sized cross-section drawings for several of their props. I found the one closest to my prop and printed it out:

Its not an exact match to my prop, but close enough to be a starting point.

The drawing has a centerline indicated on it.  The center line was aligned with the mark on the spinner dome and the pattern was copied onto the spinner dome.  Using some regular tin snips, the cutout was made staying 1/4" inside the line:

Next came the repeated filing and fitting until the prop spinner closely fit the prop and the aft edge of the spinner perfectly aligns with the aft edge of the rear spinner bulkhead. The spinner was then drilled and clecoed to the aft and front spinner bulkheads:

To test for spinner wobble, a 5' step ladder was placed in front of the spinner and a sharpie marker was clamped to the ladder with the point of the marker was just touching the point of the spinner.  With the bottom plugs pulled, the engine was turned over using the starter.  I was left with a nice, small black dot right on the tip of the spinner, so no wobble was present.

The spinner was then removed and all holes were opened up for a #8 screw and were countersunk. The spinner was then prepped, primed and painted red.  

The prop was removed and both of the spinner bulkheads received #8 platenuts (K1000):

The prop and spinner bulkheads were re-installed and the 1/2" bolts were torqued to the proper torque as specified by Sensenich.  All bolts were then safety wired:

Click here to go to Spinner page 2