Door mod progress

Working on various door mods - those do take so much time :)

I trimmed the cabin cover door flanges for the McMaster Seal to fit (I settled on the 1120A311) so that it sits at the right distance and roughly its width from the edge of the door:

Closed door with the McMaster seal in place

Seal edge distance markings on the door

Seal edge distance markings on the door

I also riveted the door reinforcement plate nutplates:

Door reinforcement plates with nutplates riveted on

The door pin blocks required some trimming to fit, and then I had to trim the cabin cover flange a bit for them to go in, as well:

Door pin block after trimming the outboard side

Door pin block fitting snuggly against the door

Slot carved out on cabin cover to fit door pin block

Slot carved out on cabin cover to fit door pin block

Door pin block fitting just right into its slot, with the door latched

I got to the point where the blocks fit and keep the door in just the right place, but the slot I trimmed into the cabin cover was not enough to keep them flat - there was still a bit of a gap on the outboard side, which would make it hard to match-drill the block holes at the correct angle. I didn't want to trim the block or the cabin cover more as that'd introduce play, so I filled  that with resin instead, and closed the door with it in place:

Cabin cover pin block slot full of wet resin

Pin block full of wet resin (after wax release was applied to it)

The result was of course a bit messy (expected), so after match-drilling its holes, I trimmed off the excess with the Dremel:

Door pin block match-drilled and bolted in place

Resin remains after match-drilling door pin block

Trimmed resin remains from door pin block slot

I then attached the door pins - pretty easy to do, I started by trimming the pushrod to 13/32" inside of flush with its locked position, and that was pretty close to the final position, except for the clocking which required a lot of slow iteration:

Trimming latch pushrod for pin

Pin attached to pushrod and clocked properly

Pin in place with correct clocking and Delrin block

Pin going through fuselage with the door locked

With the blocks and pins, the doors now latch very easily.

Finally, I trimmed the center latch blocks a bit so they'd be flush with the cabin cover door flange - I could use that spacing for the seal, but I'd rather have a larger contact surface against the block, and trim the seal later instead:

Trimmed center latch block

Center latch sitting flush against cabin cover flange

I'll wait to actually drill those blocks' holes into the deck until the cabin cover surface is finished so they remain flush.

With the whole latch mechanism done, I can go back to the main parts of finishing up the doors.

Time lapse:


Total cabin door rivets: 72
Total cabin door time: 132.2h

Door latching progress

Vacation (staycation?) week, so we got quite a few hours in.

We installed the latch system, including the center latch and the Aerosport low-profile handle. This video was extremely helpful, but we still deviated from it by not separating the middle pushrod and rack, and instead clocking the handle without the center latch in place, then using a string to pull the longer pushrod and rack through the center latch - this prevented having to do safety wire work in the tiny space left in the latch pocket, which would have been a pain. In case it helps anyone, the steps were roughly:
  1. Attach string to tip of aft pushrod (use a simple knot - you'll be removing it through the inspection hole with tweezers later)
  2. Insert aft push rod, pull the string through the inspection hole (or the latch pocket hole), then pull the pushrod back out leaving the string through
  3. Insert center pushrod/rack
  4. Attach latch mechanism
  5. Attach center rack to mechanism, clock it so that in the open position (horizontal), the pushrod hole for the pin is aligned with the inspection hole
  6. Insert center latch block (no need to attach it) and check that, with the center pushrod still straight in relation to the rack (look through inspection hole), it doesn't hit the block in the closed position - if it does, offset center pushrod forward by a couple of teeth and repeat until it clears (you may be fine on the first try, depending on the exact position of your inspection hole)
  7. Insert and attach forward rack to mechanism, clock it so you can just get to the open horizontal position (one tooth shorter than the position where it hits the fiberglass)
  8. Pull a bit of string out from center latch hole, run it through the center latch slot, then attach center latch block, keep it loose to make the rack hole easier to hit
  9. Pull aft pushrod and rack through using the string (use a light to help get it through the slot)
  10. Untie string through inspection hole and remove it
  11. Align the center pushrod and aft rack, insert pin to connect them.
  12. Check handle motion range (horizontal closed to horizontal open), curse if it's off.

Latch mechanism attached to the door

String running through the center latch block to pull the aft rack through

Latch racks clocked into position

We then made the pointers to mark the cabin cover for drilling, tapped the pushrods and installed those, then made the markings while holding the door flush:

Door latch marking pointers

Pointer attached to the forward pushrod

To make the marking more clear, I used the red marker on the tip of the pointer, and that left a small but clearly visible red dot on the cabin cover:

Pointer tip dipped in red ink

Red dot at the location to be drilled (tiny - click to see larger)

I drilled the cabin cover on the dots, and with just a little further deburring, the latch pushrod went right in!

Forward latch hole after drilling

Aft latch hole after drilling

Pushrod going through latch hole

Getting the McMaster seal to fit (without requiring a lot of force/overcompression) required careful iterative trimming of the cabin cover flange to get it at the right height. In the end, the seal part number we ended up preferring was 1120A311 - having the grip "finger" on the back helped keep it in the right orientation along the curved back side of the flanges, and will be easier to fill with resin later:

Door latched with the McMaster seal in place

Door latched with McMaster seal and center latch in place

For the left door, the reinforcement plates were a bit farther outboard, requiring trimming a little bit of the door pocket surface, which turned out to be thinner than I expected :/ so one of them had to be rebuilt by carefully inserting a couple layers of fiber inside the door, then adding another layer outside:

Hinge pocket edge sanded to fit reinforcement

Hinge pocket edge sanded (too far) to fit reinforcement

Fiber+flox layup to close off the hinge pocket again

Laying top fiber layer for closing off hinge pocket hole

We let it cure with the reinforcements in place to make sure they'd still fit:

Hinge pocket reinforcements installed over filled/closed areas

For closing off the hinge pockets (for one, so the seal has something to press against), we made a plaque with 3 layers of fiber:

Laying up fiber plaque for closing off hinge pockets

Fiber plaque for closing off hinge pockets

then cut it into the right shapes so they fit just slightly recessed in the pockets, and sanded the pocket edges to add a couple more layers on top (and to follow the curvature of the cranial recess):

Quarters of the plaque marked for further trimming

Hinge pocket close-off plaque, trimmed for shaping the cranial recess

Hinge pocket close-off plaque

Now, in addition to actually laying up the fiber to close off the pockets, we need to repeat this for the opposite door - adjusting the left door seal gap and trimming the close-off plaques for the right door.

Time lapse:


Total cabin door rivets: 40
Total cabin door time: 113.4h

Both doors attached

I started working on the cabin cover door flanges for the McMaster seal:

Cabin cover door flanges trimmed for McMaster seal

Cabin cover door flanges trimmed flush for seal

I had ordered a couple of different versions of the McMaster seal (just 10ft of each, the minimum they sell) to try out sizes, and it looks like the 1120A313 was the best fit, but I still need to adjust the gap from the door to be uniform before I confirm that:

Test-fitting the McMaster 1120A313 seal

Test-fitting the McMaster 1120A591 seal


I also took the opportunity to test fit the Airward reinforcement, and to my own surprise, the bolt holes were straight enough that it fit easily:

Bottom side of the Airward door reinforcement

Top side of the Airward door reinforcement

I then started the other door. I used the same technique, by cutting slots around the door to find the right depth (until the slanted part of the cabin cover shows), except this time I knew what to expect so I was much more aggressive in how much I removed, starting with the scribe line and going deeper in many of them:

Left door in place with "sighting" slots

Left door taped in place for drilling the hinges

Left door hinges attached to the door

After the doors were sanded to fit, there were only a few small flaws in the bonding of the door halves that will need to be filled:

"Air bubble" that was left when the doors were bonded

With this, after only about 40 hours of sanding, the hardest part of the doors (getting them to fit) is done!! Lots of finishing left, plus the latch mechanism, seal gaps, etc. Measuring the window heights on both sides, the difference was minor (about 0.1" in the front, 0.05" in the back), so I'm happy with the results.

Time lapse:


Total cabin door rivets: 40
Total cabin door time: 99.1h