Experimenter is a magazine created by EAA for people who build airplanes. We will report on amateur-built aircraft as well as ultralights and other light aircraft.
Issue link: http://experimenter.epubxp.com/i/378679
Is your family secure? Are you sure? Your current life insurance policy may contain an exclusion for pilots. EAA's Accidental Death and Dismemberment Insurance Plan will help fill that gap for less than a $1.50 a day. Take care of the people you love. Get an instant quote and purchase your coverage today at EAAInsurance.org. Personal Insurance Coverage is underwritten by Starr Indemnity & Liability Company, a Texas insurance company, has its principal place of business in New York, NY and is an admitted insurer rated "A" (Excellent) by A.M. Best Company. Administered by Falcon Insurance Agency, Inc. EAA Experimenter 37 tip of an 82-inch-diameter propeller, or at the 95-percent-span radius. Going to 8-27 shows that up to 12.5 percent of the blade chord could be removed, or at a blade width of about 4 inches, I could remove up to a half inch of the leading edge! This repair was going to be well below this limit. The ding was about 3/32- inch deep. See Figure 3. The tools you will need for propeller repair include a set of fi ne fl at and round fi les, spoon fi les, and fi ne (600 grit) wet/dry sandpaper or crocus cloth. See Figure 4. Start with a wide, fi ne, fl at fi le, using it to smooth out the bulge in the outer airfoil shape of the propeller caused by the impact of the stone or whatever. Next, blend the dent into the edge of the airfoil with about a 6-to-1 slope. In other words, for a dent depth of 3/32 inch, times 6 gives an 18/32- or 9/16-inch taper. The bottom of the dent must also be cleaned out to ensure there is no crack. After getting the slope contour and bottom of the dent cleaned out, examine the area with a magnifying glass to make sure no crack remains. The surface should be etched with something like Zep, Alumiprep, or Alodine to expose any resid- ual cracking. Once satisfi ed that the area is completely cleaned of damaged material, round the edge to match the airfoil profi le and blend the repair into the surrounding area. Polish with crocus cloth or 600 grit wet sandpaper to remove all traces of fi le marks. See Figure 5. Finish the prop with primer and colored paint, in this case, fl at black. See Figure 6. We added white to the tip and allowed it to cure a few days prior to replacing the leading edge tape. To clean up any edge on the paint or other imperfections, we wet-sanded the paint with 1200 grit sandpaper prior to applying the tape. It is now almost impossible to see the repaired damage. Due to the relatively small volume of aluminum removed, the prop did not have to be balanced again prior to use. Figure 6