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Sonerai Cowling Rebuild Project

By Bill Evans, EAA Chapter 266, EAA 794228

April 2020 - The lower cowling I made for the Sonerai now takes the better part of a day to install, and the result leaks so badly that I need to tape it up, which looks unattractive.


Sonerai cowl fitted.

I found the mould and firewall template I used to make the first cowling. My friend Gord's idea is to use a full-length, say 2-inch, piano hinge to attach the two halves and abandon the Hartzell latches, which works, but bends the cowling, resulting in air leaks.

This is what Jabiru does: piano hinges. So does Van's. — Ed.


Top cowl mould.


Bottom cowl mould.

I am seeking advice of chapter members near me as how to proceed to prepare the mould to lay up a new cowling. I'm no expert in composites.

There will be changes:

  • The NACA (carb air) duct will be scrapped. The new SS duct/filter will be just aft of the firewall and have a scoop inlet above the upper cowling.
  • The cowl flaps will be scrapped, and I'll go with the blister Gord used for the Jabiru kits he built
  • The facing angles glassed into the edges of both cowlings will be removed, since piano hinges will also provide sealing.
  • I may retain the liquids drain mast, but it could be moved to an angle on the firewall instead of the lower cowling.
  • The oil cooler will be removed from the lower cowling and installed with rods to the lower engine.
  • The eight Cam Lock fasteners I used to close the cowlings will be replaced by the piano hinges.

Stay tuned for this adventure.

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