Lower Cowl Rejoin

Hinges were cut to mount to the newly created cowl flanges. Again, I tried as best as I could to shift the hinge eyelids so they wouldn’t be seen in the split.. Given the curve in this area, it wasn’t as easy as the horizontal sides, but I did the best I could. When I wasn’t able to maintain it I favored the front rather than the aft as that would be the area most visible.

Match drilling hinge to cowl flange

Match drilling the other half of the hinge was a little more challenging to hold the cowl in proper position. I opted to use the forward fairing on the aft part with the 8 clecos where screws will hold things together to line up the aft end. I also used a small piece of scrap metal drilled and cleco’ed to the spinner area to hold the forward part of the cowl in position. I also used some duct tape along the split itself and removed as I went and got more holes match drilled and cleco’ed.

Getting ready to match drill other hinge half.. gap not quite closed fully yet.

In the below pic, you can see the cowl match drilled from the inside and outside. I feel the split gap came out pretty good.

Outside view
Inside view

Then it was time to adjust the aft part of the hinge and cut an access hole for the pin to be inserted in a fashion similar to the Aerosport pin covers on the sides of the cowl. I placed this hole just forward of where the forward cowl faring ends and made it rectangular about the combined width of the newly created flange.

Hinge pin access hole.

I fabricated a rectangular aluminium cover piece to fit the gap using some scrap. I drilled 2 holes for #6 screws to hold this cover in place.

Test fit of metal cover plate

I then did the same as I did for the Aerosport pin covers.. I place the metal cover plate into place with some packing tape around it for a release agent, slobbered a thin layer of micro over the back side, then laid up 4 layers of 9 Oz cloth and let cure. Below you can see the result after removing the cover plate. The central area between the 2 holes (where there will be nutplates added) will be cut out so the pin can be inserted.

And finally a picture of the cover plate in place after installing the nutplates and dimpling for #6 screws.

Cover Plate complete

Prior to permanently riveting the hinges in place, I did a test fit of the entire cowl again to make sure everything still fit together well.

I copied what Dr. Mark had done to the forward fairing that attaches to the area of the cowl with no honeycomb and added a metal support piece along with 8 nutplates for #6 screws. This will provide a solid attachment point between the 2.

Adding a metal backing plate and nutplates
Plate completed.
Inside view of the plate.

One of the last things to do (also copying from Dr. Mark) was to add a flange at the spinner area to provide an additional screw point and to alleviate any play in this area. I added packing tape on one side of the cowl so the fiberglass would only adhere to one side and serve as a flange behind the other half. This tape was placed such that the cut line was covered. That way I didn’t have to deal with attempting to cut the cowl halves apart again in this area potentially cutting into the newly added flange.

4 layers of 9Oz. Cloth clamped into place and curing overnight.

Below is a crappy pic of the inside where I used some scrap fiberglass with packing tape wrapped around it to clamp the newly added cloth in place along the entire spinner area while curing. Also a picture of my ugly mug to prove I actually built this plane.. 🙂

Below is the end result of the added flange.. Excess still to be trimmed away.

Then it was time to put the cowl all back together for a final test fit with all the hinges and skybolts in place. The only thing left is to add nutplates and screws to hold the top and bottom cowls together at the air inlets as well as the spinner area.

Cowl all buttoned up.

A closeup of the new flange and where the screw hole will go

Now to start working on the hidden oil door.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s