Building error crashes plane 26 years later
09-02-2004, 05:08 PM
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Building error crashes plane 26 years later
I built a Bridi T-20 trainer back in 1977, but was afraid to fly it then as I was pretty inexperienced and had never flown anything bigger than a .049 powered Q-Tee. Shortly after that I moved and the T-20 got stored away and forgotten. Since then I've done lots of flying, but never thought of the T-20.
Last year I "discovered" it and decided to get it flying. All I had to do was replace the old Kraft servos with some newer ones, add a receiver and loosen up the Veco .19 in the nose. There wasn't even a rip in the monokote.
I took it out to the field and the 26 year old engine fired right up. I launched it on its maiden flight, and it flew great. As I came by on a high-speed pass we commented on the "cool" sound it made. After a few loops and rolls I decided to land and I had just completed the turn onto final at about 40 feet in the air when it rolled left and crashed right into some trees.
As you can see the fuselage was pretty smashed up but the wing survived with only a chunk bashed out of the leading edge. When we recovered the wreckage from 30 feet up in the tree I discovered what had gone wrong. The left aileron was dangling by just the inboard hinge. The half of the servo output arm that controlled the left aileron was broken. Two of the three aileron hinges had lost their hinge pins!
When I had built the T-20 back in 1977 I used hinges with pins (like in a door) and had failed to secure the pins from sliding out. Two of the three hinges on the left aileron had vibrated out. The "cool" sound it made in a high-speed pass was the aileron fluttering. I think it finally crashed when the flutter caused the servo output arm to break.
I was able to piece the fuselage back together, replace the hinges with CA hinges and have been flying it again this summer.
The first picture is the plane 30 feet up in the tree. The second picture is the remains on the ground. The third picture is the resurrected T-20 flying again this summer.
Mike
Last year I "discovered" it and decided to get it flying. All I had to do was replace the old Kraft servos with some newer ones, add a receiver and loosen up the Veco .19 in the nose. There wasn't even a rip in the monokote.
I took it out to the field and the 26 year old engine fired right up. I launched it on its maiden flight, and it flew great. As I came by on a high-speed pass we commented on the "cool" sound it made. After a few loops and rolls I decided to land and I had just completed the turn onto final at about 40 feet in the air when it rolled left and crashed right into some trees.
As you can see the fuselage was pretty smashed up but the wing survived with only a chunk bashed out of the leading edge. When we recovered the wreckage from 30 feet up in the tree I discovered what had gone wrong. The left aileron was dangling by just the inboard hinge. The half of the servo output arm that controlled the left aileron was broken. Two of the three aileron hinges had lost their hinge pins!
When I had built the T-20 back in 1977 I used hinges with pins (like in a door) and had failed to secure the pins from sliding out. Two of the three hinges on the left aileron had vibrated out. The "cool" sound it made in a high-speed pass was the aileron fluttering. I think it finally crashed when the flutter caused the servo output arm to break.
I was able to piece the fuselage back together, replace the hinges with CA hinges and have been flying it again this summer.
The first picture is the plane 30 feet up in the tree. The second picture is the remains on the ground. The third picture is the resurrected T-20 flying again this summer.
Mike
09-02-2004, 11:08 PM
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RE: Building error crashes plane 26 years later
Actually the fix was easier than it looks. The fuselage pieces went back together like a jigsaw puzzle. I just pulled off the old monokote aft of the wing saddle, glued the balsa back together and recovered the aft section of the fuselage. I actually still had the rest of the roll of metallic green monokote from 26 years ago; there was just enough.
Mike
Mike
