Cowling access doors

once the cowling was fitted together , I swept a bit of Micro-Balloon and epoxy into any of the gaps. The upper cowl was waxed so the Micro only stuck to the lower cowl. The final hole diameters were opened up and countersunk washers were bonded on. The washers were first sandblasted on the bond surface. The cowl was sanded and then cleaned with isopropyl alcohol. The washers were bonded with T-88 structural adhesive.

Sand Blasted Washers

These washers are available from Aircraft Spruce. They solve the problem of the fastener sawing thru the fiberglass. They sit slightly proud. I taped up every one so the final finish will be polished stainless steel.


When I put the cowling halves together, I needed an accurate way to trim the inlet flange. I wanted a nice planer trim. As I mentioned before the neatest way to trim fiberglass and graphite laminate is to use a grout cutter and a multipurpose vibrating tool. I set up a MDH wood surface by bonding it to the inside of the cowl with Bondo. I then set the tool flat on this surface and cut away the inside. It was perfect! Nice and even and planar.

MDH trim planes

This shows the cowl with the MDH plates bonded in . The grout cutter sits flat on the MDH surface.

Final Cowl inlet trim

The final trim.

access door layout

The next step was to make two access doors for the oil dip stick and the oil filler cap. This broke my heart, having to cut out these panels on a surface I worked so hard to get perfect. But it beats the hell out of pulling the cowl every preflight to check the oil. The section of the cowl I cut out will become the access door. Before I do that I need to transfer these outlines to the inner surface. Once I marked the inner surface, I applied 5 coats of Carnauba mold release wax to the inner surface (IML Inside Mold Line) . I then cut 4 ply's of glass and laid them up centered on the outline.

door doublers laid up

After 2 days of curing (its getting cooler in Texas) the doublers were ready to be released. They were separated and set aside. Later they will be marked for trim after the doors are cut out of the upper cowl.

beginning of the cut

I used a .030dia drill to start the cut. Once I connected the holes, I was able to insert a small air operated scroll saw. I took my time, and cut out both doors. Once the doors were free, I sanded the edges even and trimmed back the hinge side for clearance.

raw cut

when I laid out the door, I purposely set the hinge side on a contour element line (straight line) so there would be no binding of the hinge. I used a MS aircraft hinge and using countersunk Cherry N rivets, I attached the hinge temporarily using Clecos.

Door with Hinge

The next step is to mark the backing doublers for trim.

Bonder door doubler

the doublers were trimmed and the edge beveled 20:1. This reduces the peel forces on the edge off the doubler. I used t-88 adhesive and Cleco clamps and bonded it together.

fairing in the doors

The final step was to get the surface back to the original smoothness. I waxed the door and then assembled them I dragged a coat of micro into the small gap between the cowl and the door. This micro will fill any gaps and remain with the cowl and doubler.






















I have made more progress that I am saving for the next update. I am currently setting up the engine for its first run. I need to install a pressure gage and oil pressure sender. I need to rewire everything and set up new throttle and choke cables. I just ordered a new Prop from CSG in Canada.