Tuesday, November 17, 2009

Fabric Clips

Today was a learning day. That means a simple project took way to long but now I think I understand why. I started with great expectations of how quickly fabric clips could be installed instead of rib stitching. The first three went well and the the next ones wouldn't go in and if they did they popped back out on one end. Not very good for that secure feeling you need flying on turbulent days. That really makes a nice clean hole and eliminates snagging in the twill tape. Time to stop and see what I could learn from Jim & Dondi. Jim had a great suggestion which helped. I took my cheap soldering iron, 25 watt, and pointed the end to melt holes in the twill tape and fabric. It helps to have a light behind the wing and dim light on the side you're working on. That way you can see the holes in the ribs through the twill tape. In far less time than you can layout and punch hole for rib stitching the holes are neat clean and ready for clips. When the clips go in correctly they snap into place and you know they're in correctly. On my ribs the clips which were added in the field per the various service letters were not drilled correctly. I can only assume the factory template was wrong or some one made their own without checking the dimensions carefully. The dimension for the holes in drawing 9 with service letter 22 shows the center to center dimension to be 1.353" +/- .010". The holes are drilled with a #40 drill ( .093" dia.) so the edge to edge distance the clip hooks over is 1.245" to 1.265". All the holes fo added clips were 1.282". That doesn't seem like much but it's enough to pop clips back out since the second leg stays held straight and not bent in to lock it in place as normally happens. All I had to do was measure each set of the added holes and file the inside of the holes with a small rat tail file until the dimmension was just back in tollerance. I wanted to leave as much metal as posible for future recovering in case there is any hole damage removing clips in the future. In all it was about a third of the clips on the upper surface which had problems. All the factory holes were fine and the clips snapped in just great.

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