Steve's Zenith 640 site
Landing Gear
What it should look like when I am done.

I had a 1973 Cessna 172 with a 180 hp mod. It was a good plane but I decided I wanted to build my own plane. It had to be fun.but practical. A Zenith CH 640 seemed to be a good compromise. For the building part I wanted to be realistic. The 640 is a simple to build design. It uses a high tech form of POP rivets. The 640 is mostly metal, simple to build, 2+2 seating, easy to insure, easy to fly.

It is also known as a Zodiac CH 640.

Categories with no links means I haven't got that far yet


Words of warning;

Read and try to understand what is supposed to happen. Read ahead. There is parts that say rivet ribs together and on the next page it says de-burr and paint. Kind of hard to do if you have already riveted it together. Also if you follow the exact dimensions it will not go together. Do not drill and rivet ribs to spar as per drawings. The pre drilled holes in the skins do not match the dimensions of the ribs. You will wind up with rivets in air or into a radius. Tape parts together first and then "adjust" things a little here and there before you start drilling. Unlike in the cartoons, you can not slide the hole over a little after it is drilled. The directions also say rivet rudder hinges with the factory head on inside. This leaves a "shop head" that sticks up in way way of the rudder hinge bolt. I was told by Zenith this was obvious, and I should have known not to follow their directions. Also there is a 119 mm wide lower rib that is supposed to go into a 116mm wide spar doubler channel. Heavy bending needed here.

The upper skin holes and rib placement did not match the dimensions in the plans. When I asked for the center line dimension between the pre drilled upper skin holes I always got the run around. I think the skin was too long and they referenced the holes from the edge. After many phone calls and emails, I figured out I was never going to get that dimension. Very strange! This lead to building a new rib myself, since the original one had too many holes in the wrong place, even though I paid for one in the kit.

I am trying to think of the next step. Ordering the parts ready made should be quicker. But for how many problems I had, I could have built everything from scratch. I am concerned if I did everything from scratch It would take too long and I would give up before I finished. My rudder is finished, it is very nice and I am happy with it. Once I battled all of the problems the rudder went together very nicely. From a pile of parts to a finished rudder was about 16 hours. To get the pile of parts re bent, re drilled and remade before assembly was about 30 hours. Not acceptable. I should have been able to pull the parts out of the boxes, measure as per drawings and drill and rivet it together. 16 hours only. There should have not been any "rework every part" before starting assembly. Every dollar I gave Zenith was perfect and fit their wallet without any modification. I expected the same.


As of now I have been stopped for almost 2 years. 50 % of that is just to re-think. the other 50% was other mostly good things got in the way. In the mean time Zenith has removed the CH 640 from two of their three web sites. They don't seem to care about it anymore. They seem to be going after the light sport "gold rush".