Sunday, November 29, 2009

Control Surface Paint Stripping

Today was one of the perfect fall days here in Virginia. The dog and I spent the afternoon outside. He slept while I stripped paint from one aileron and one flap. It looks like Bill had decided not to use these. The aileron needs a little work and we have one spare new old stock flap. The aileron looks easier to fix than the spare we have which has a little corrosion. I think I'll sell the spare flap when I'm done. I'm assuming the better one will bring more money. The used ones are in very good condition. They do need new piano hinges, but those will be easy enough. At least with spares I have alternatives if things don't work as planned, does anything?

Saturday, November 28, 2009

New Right Wing Spars

Today on my way home from visiting the grandkids in New York I stopped to visit Bryan Cotton in Elmira. He is also rebuilding a Cessna 140 and had a set spars which he did not need for his wing. As a result I now have a new (used) set of spars so I can start rebuilding the right wing. I'll need to clean up the spars and epoxy prime them before I start taking the old wing apart.

Thursday, November 19, 2009

Picked Up Control Surfaces

Met with Bill today to get the control surfaces, engine cowl, struts and other small parts. It was a rainy day but very exciting. There are enough extra parts that we should soon have all the control surfaces inspected, repaired and ready for primer.

Inspection Rings

Installed 2 inspection rings aft of the rear spar on the left wing per Cessna Service Letter 39A. Waiting for warm dry weather to continue with this wing.

Wednesday, November 18, 2009

All Fabric Clips on Left Wing

The clips are finally done. Not bad once you know what you're doing and fix someone else's mistake. With clips that closely spaced it really looks secure. The closer spacing on the upper surface is required per Service Letter 42. Without them the plane is not allowed to do aerobatics or fly in extreme turbulence. Ok, I can live without flying in extreme turbulence, but it is nice to know the fabric is well attached. The upper side has 139 clips and the lower side has 68. As a double check to make sure I didn't miss any, the Cessna parts manual says you need 207 per wing. The lower side of the wing took about 1-1/2 hours to apply the twill tape, melt the holes and install the clips. The only problems were with the thicker metal due to the landing light mounting.

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.

Monday, November 16, 2009

Left Wing - First Coat of Poly Brush

After days of rain and a couple days to let things dry out, I was able to put on the first coat of Poly Brush. I should have taken the picture before it got dark out. It looks ugly but came out real well. A few drips from the first side had to be cleaned up but the fabric is sealed well. Now for the fabric clips and then tapes. The brushing was done with the wing horizontal and letting each side dry well before rotating.

Sunday, November 15, 2009

Wing Stands

Before I started working on the wings I realized I needed some wing stands which were better than saw horses. I had used Saw horses for a set of Cub wings I repaired but my attic workshop is rather small with everything in it.

-  I needed something light enough to carry up and down the steps to work outside.
-  They needed to be stackable when not in use. They needed to easily rotate and lock in position when working on the wings.
-  The wings had to be able to be taken on and off by one person.

 There were drawings for stands in the 120/140 club news letter (Maintenance Advisor #030) from Robert McDaniel which met some of these needs but not all. They did however give me good ideas and I used the Universal Joint, Pivots and Vertical members almost exactly as shown.

To load the stands by myself the legs needed to be turned inward so they would not tip with the weight of the wing during loading. I didn't want to fasten them to my attic floor or carry sand bags up and down the steps. OK, I'm lazy. This meant they could not be trianlges of 2x4s since the diagonal brace would hit the wing when rotating. Instead I made 4 legs from 2 10 ft. lengths of 3/4" conduit. I bent them with a cheap conduit bender, one of those well used must have tools.

The bending took a little thinking but they came out just great.

I bolted the conduit to the spreaders and vertical members with carriage bolts to provide feet to reduce rocking, as if MY floor might not be level.

 I added an Indexing Plate at the root end with 2 3/8" bolts as locking pins and holes every 15 degrees. It really works great.

Pictures (Double Click for large image):
1 - Root End Stand

2 - Index Plate and U-Joint

 3 - Index Pins

4 - Universal Joint and Pivot Pipe

5 - Tapered End of Dowel

6 - Stop End of Dowel

7 - Rounded Edge of U-Joint

8 - Tip Stand

9 - Tip End Plug

10 - Tip Stand Plugged In

11 - Stacked For Storage

 To install wing on stands, see pictures 12 thru 15, you lay the wing flat on the floor. Attach the U-Joint at the root and safety pin it.
Lift the wing with the tube cap and one washer removed.
Slide the pipe thru the pivot hole in the vertical member and install the washer and cap.
Lock the indexing pins in the horizontal position.
With the tip plug/pivot installed in the tip stand, lift the tip end and push the plug into the nav. light socket.
You're now ready to work.
Remove the wing in the reverse order making sure the wing is locked horizontal first.

12 - Install U-Joint At Root and Safety Pin

13 - Root end on stand First

14 - Lock Wing Horizontal

15 - Plug in Tip Stand

Wednesday, November 11, 2009

Tuesday, November 10, 2009

Left Wing Fabric Cut outs

Cut fabric for wing fittings, tank filler, etc. Glued down around cuts. Shrunk up wrinkles from cuts at 250 deg.

Sunday, November 8, 2009

Left Wing Applied Fabric

Applied Poly-Fiber HS90X Fabric to wing using an envelope. The only problem we had was the slightly loose fit around the root rib. In hind sight I wonder if it would have been better to use the 225 deg iron to ever so slightly shrink the fabric to give it a snug fit before attaching it to the root rib. I eventually got out the few wrinkles but think they could have been avoided.