DATE: 9-6-2025 – TIME: 1:00
I started the build process as described in the IPL on sheet FR-1, page SD75-FR-01 in the “manual” stack. I had 2 problems, the first being that the description with respect to assembly is lacking, to put it mildly, and the other is that I did not have the SD75F41-3 on hand as it was / is being powder coated. Consequently, rather than trying to follow the description in the IPL I went my own way, as described below.
The rear bottom skin LS75F1-1 had already been scuffed for priming but due to weather delays I had not primed the skin so was not in a position to do any permanent riveting.
I lay LS75F1-1 on my bench with a piece of kraft paper salvaged from the packaging beneath it. I then used a fine point sharpie to draw the outline of the skin on the paper, removed the paper and folded it in half creating a crease down the centre. I now repositioned the paper on top of the skin, aligning the trimmed edges along the edges of the skin and used the crease to mark the centre line on the skin. I double checked the centre line with my 32nd ruler and marked the centre line.
The Zenith instructions say to mark the centre line on SD75F41-2 and SD75F2-4 but I don’t see the need to do this at all as all the holes are match drilled.
At this point I am waiting to get the SD75F41-3 steel part back from powder coating at which point I will place it against the SD75F41-2 & SD75F2-4 assembly clecod to the skin to mark where the bolt hole needs to be in the bottom skin LS75F1-1.
Meantime, here are some pics of my process so far…
The IPL doesn’t say which rivets to use with the HT Frame, referred to as the HD Frame on page SD75-FR-01 when riveting the doubler, SD75F41-2, referred to as the V brace on page SD75-FR-01 to the SD75F2-4 HT frame. On page SD75-FR-01 it says to use A5 rivets, except that the holes common to those two components that do not include the SD75F41-3 front skid pick up bracket are match drilled final size A4, not A5. The holes common to SD75F41-2, SD75F41-3 and SD75F2-4 are drilled A5.
I’m not a mechanical engineer and as my life could be on the line, I don’t want to just “assume” that I can use A4 rivets, or drill out and use A5. I did try doing a search on the Zenith.aero forum but there is nothing there and the last time I looked on the Zenith Builder’s Resources there was nothing there on the 750 SD other than a promise to have something at some point.
To be blunt, this kind of crap doesn’t engender confidence that the Zenith aircraft engineering and quality control are any good.