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In order to have a nice smooth and clean looking top cowl with no fasteners, I’m doing a hidden oil door hinge for opening. I utilized a spring based hinge so the door will pop open and stay up when opened.

The first step was to trim the oil door on the scribe lines that came with the Showplanes cowl. This piece matches the curve of the cowl perfectly.

Then I marked out a 3/4″ line for a flange on the recessed part of the oil door location. A small amount of sanding was needed to have the door fit in the recess area. You can see the door fitting nicely below and the marks for the flange behind it.

I cut the recessed area carefully and seeing it also follows the curves of the cowl, I used it as a stiffener on the back side of the oil door. I utilized flox and drilled a bunch of holes (which will be filled in later) to make sure there was a good bond between the two. I also used clecos around the perimeter to makes sure the door held tight to the cowl during cure.

I again used some flox and some packing tape to fill in the gaps between the spring hinge and the oil door. The hinge sat an an angle and it required a bit of a buildup to fill in the gap.

It was then time to work on the opening hinge mechanism. I utilized piano hinge for this. On the oil door side it’s just wide enough to allow the hinge to pass through the opening.. The mating side on the cowl is a little longer and I made it a little longer on the forward side, which required a little hogging out of the foam area around the oil door perimeter.

Below is a bigger view of the front cowl as I was prepping for drilling holes to attach the hinges to the cowl and oil door. I used the normal hinge pin for fitting as it’s slightly bigger than the bowden cable wire that’ll be used.

Below you can see all the hinges riveted and the Bowden cable roughy in place. This will ultimately be attached to the inside of the cowl and the pin cable will be cut so that the pin is just inside of the left air intake hole. I’ll be able to grab the pin and pull it causing the oil door to pop open once the pin has been extracted far enough. I’ll need to wait until I finish the air inlet ramps to complete the cable part of this.