Back at the house I the post flight exposed the problem. The main spar is made up of two one inch square tubes. From the bottom they looked fine but from the side I could see a crack. I took off the seat and discovered that both tubes were cracked on the top and both sides. With a little pressure I could make the cracks open slightly. When I lifted the front wheel and rocked it up and down I could see that there was very little holding the rig together. Conceivably, if it didn’t collapse during take off, the spar could have let go with me on the breakaway side, only connected to the wing and motor by the seat belt. I suppose its possible I could have stayed with the rig and landed but more likely, I would have fallen through the seat belt, completing my last flight. Wow! It was obvious that the cracks had been there for awhile but I hadn’t seen it.
It probably started when I had the crash at Bubba’s. The trike came down hard and bent the frame downward, behind the seat. I didn’t worry about it at the time. Actually I liked the new configuration because it moved the prop wash slightly upward and lowered the seat and center of gravity. I joked that it was more like the geometry of the trike buggy. Well… the top of the tube is were it crimped the tubing and thats naturally where the crack would form. The side cracks probably opened up recently. At least I hadn’t noticed them and I think I would have.
It took Mike Lange no time to repair the spar.
While I was at it I balanced the prop and installed some bullet proof line keepers. I also raised the seat about 5 inches and padded it with 2 inches of memory foam.